questions and answers about japanese hot tubs, mainenance and hinoki wood qualities

  • FAQs:

  • SIMPLICITY + SATISFACTION:
    Installing a wood bath tub might be thrilling for you and a little worrisome for your contractorif he is doing it for the first time. Actually, installation, use and maintenance of a hinoki bathtub is very straightforward and you will be surprised how simple it is. Please look at the FAQ`s below and feel free to ask anything you do not understand.
    Kiso valley: selective logging ->
    bathroom renovation
    Q #39

    What is the feedback from your customers in Singapore - regarding mold experience on the bathtub. I am very worried about this, because here everything gets moldy, even shoes.

    A #39

    About the mold: you should provide a good natural ventilation (open doors or windows after the tub). Forced ventilation alone, will not be enough.
    In any case, we treat the tubs with a hydro-repellent product (see here).
    http://www.bartokdesign.com/japan/downloads/kihadaichiban-description.pdf
    "KIHADA ICHIBAN" is applied by brush or roller. It does not create a coat, it actually penetrates inside offering lasting protection whithout occluding the pores of wood.

    Hinoki wood is generally unfinished to convey its soft touch and natural aroma. Anyway, this new product (based on the nano-technology and using a fluoride base) operates like the silicates treatments used in europe to waterproof bricks or plaster.
    These products penetrate inside the material so they do not leave a peel, they do not alter the color, luminosity and aroma of the wood.

    We have been using this product for 4 years now.
    It is great to prevent mold and we did not have any claim from Singapore customers so far.

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    Q #38

    I read because your tub is planed, it does not need sealants or any chemical product. If soy sauce gets spilled on it and left to dry, would it stain or can be simply wiped off?

    A #38

    About the finishing, we offer 2 options:

    1) simply planed: in this case you have to wash away immediately any spill or it will stain. If you get a stain, blot wisely with some bleach and rinse promptly until the stain is removed.

    2) treated with "kihada ichiban". This product is a hydrorepellent which does not create a film on the wood. It is very safe and environmental friendly but it is a chemical product.
    Please find more info here:
    http://www.bartokdesign.com/japan/downloads/kihadaichiban-description.pdf
    In this case the spill will not penetrate the wood. The manufacturer warns that the hydrorepellent effect might diminuish after 2-3 years but in our experience we could not find considerable performance loss.

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    Q #37

    What is the difference between hinoki and "Port Orford cedar" (Port Orford cypress, Oregon) for asthma?

    A #37

    I am not a specialist but the composition of the resin within the wood fibers of Port Orford Cedar and Hinoki is very different.
    Actually one of the active aromatic components which has been isolated and is frequently used for viral protection and anti-allergic products is the hinokithiol.
    Hinokithiol is present in Taiwanese hinoki and in Japanese Asnaro wood.
    It is included only in small percentages in japanese hinoki! and if I am not wrong, it is completely absent in american cedars.
    Please find more info here:
    http://www.bartokdesign.com/japan/0-blog_news/new_product_hiba-oil.php
    If you are interested in the aromatic properties of this wood you might also consider ordering a bottle of oil and try if it works in your case.

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    Q #36

    What is the difference between asnaro and hinoki wood?

    A #36

    * hinoki: white/pinkish, with a delicate lemon scented aroma. more expensive. more delicate (because it is lighter). Japanese are crazy for hinoki because of its "pure" image.

    * asnaro: nice honey color. It has a stronger forest aroma. 20% cheaper than hinoki. Easier to maintain (because is slightly tanned and because contains more hinokithiol oil). Popular for export for its color and cost-performance.

    Please refer also to our hottub product page

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    Q #35

    Are your outlet tubs new or second hand?

    A #35

    Our outlet tubs are brand new, spotless tubs that were wrapped in poliethilene sheet from the very day they were completed.

    An outlet tub is about 20% cheaper of a custom order tub with the same size/material.
    This does not mean in any way that those tubs are faulty or old.

    Most of our outlet tubs originate from 2 cases:

    1) The tub was custom ordered and the client either canceled the order or asked for a size/shape modification that required a new start.

    2) The tub is made optimizing some material we have in stock, in most cases left over from a larger job. We can define the sizes of the tub based on the length of the material we have - minimizing the loss - as opposed as cutting longer planks as we have to do for a custom order tub.
    Secondly, we produce sizes easy to build, in most cases with a width around 75cm to
    minimize the necessity of a top frame border.
    Lastly, we can work on a free schedule, between one job and the other.

    This are the only reasons our outlet tubs are affordable and the core concept of our double-smile system: you are happy, we are happy too ...!

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    Q #34

    How many gallons one of our tubs can hold?
    We are trying to figure out how big of a water heater do we need.

    A #34

    in you case, 500liters (132 gallons) is the full volume of the tub.
    You can subtract 15 gallons for the bather and another 15 if you do not want the water to overflow from top.

    You can adjust the amount of water as you like.
    Recently, in the land of "up to the shoulder soaking" is becoming popular the half-body bathing (keep the water up to the waist).
    In this case you would be able to soak for longer periods and enjoy the minus ion atmosphere originated by the steam rising from the tub.

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    Q #33

    Hello,
    I've been really interested in your wooden soaker tubs. I do
    have questions about the tub that would help to re ensure the tub wont
    leak. If all is answered, I would love to get one!!

    1. what kind of joints are used for the wall panels and kind of glue. it
    looks like there are many panels glued up to make the height of the walls..
    2. what kind of joint is used to connect the floor with walls....

    If you can anwser these question with any drawings would be great...

    A #33

    Thank you for your interest in our japanese soaking tubs.
    Please find enclosed some pictures of our standard details. Click on the thumbnails for an enlarged view.

    planks-1.jpg planks2.jpg

    we laminate the wood using wood dowels and epoxy resin (+
    curing agent). There are no metal parts.
    Adjoining planks are cut together so the cutting angle matches perfectly.

    planks3.jpg planks4.jpg

    the corner joint is realized with tongue and groove + epoxy resin.
    long stainless screws are used to provide extra sturdiness.

    IMGP2103.JPG IMGP2430.JPG

    Honestly, our tubs do not leak. If you use it regularly (everyday or every other day) your tub will work perfectly without any maintenance.
    The only thing you should pay attention to is the fact that wood tubs are vulnerable to dryness. If you leave the tub unused for long periods it may crack. It is difficult to determine exactly at which point critical conditions are reached. It depends on air temperature/humidity, ventilation, heating equipment etc.

    In any case, when you leave the tub unused for a week or more (let`s say 4 days or more as a doublesafe), leave 10cm of water inside and you won`t have any problem.

    Do not hesitate to contact us for any question.

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    Q #32

    We do enjoy our hinoki tub, although we have had some minor cracking with some black growth on the outside of one of the corner joints. We've also found that hair and skin cells seem to stay floating on the surface even though we always shower before entering.

    A #32

    I am sorry you are having some problems with the tub.
    About the dust staying afloat, I do not think it is a problem of the wooden tub, although chances are that when you drain the tub, small particles attach to the wood more easily than it would be in the case of an enamel or acrylic tub.

    I think you can get rid of these light particles in 2 ways:
    1) letting the tub overflow from the top
    2) using a thin net to skim the surface of water

    About the mold and cracks, please send some pictures, I`d be glad to advice.

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    Q #31

    I am enjoying my tub, which is installed on a deck outside my house. I was wondering if it is OK to put some sort of sealant on my tub, like the kind of sealant one would apply to teak wood, for example. Or, should I just leave it as-is and cover it up to make sure it doesn't age too much because of the sun, etc.

    A #31

    I am glad you found a good solution for the tub.
    If you apply a coat on the wood note the following:
    - The tub will loose its natural "soft" touch
    - The tub will loose its aroma and its skin-soothing properties
    - You would have to seal it inside and outside (including bottomside) to prevent unbalanced behaviour
    - Due to the oils contained in the wood, the coat may not stick uniformly and may detach. Consult also with the maker of the coating product.

    Generally we recommend to use it untreated or apply a natural oil to hydratate the surface of the wood.

    Additionally there are also some non chemical clear wood treatments which last one year and provide extra protection against mold.

    Please let me know if you need some product.
    If you have a specific problem, please send pictures of the tub and the installation conditions.



    Thank you. If I do not treat it, will it deteriorate more quickly than if I treat it? I like the way it is but am worried about it deteriorating. I am having a cover made for it to keep it out of the weather. However, it got quit a bit of sun last year and cracked in some places. It does not leak, and the cracks are probably natural and not a problem. I like the way it looks now that it has aged for one year. I just wanted to make sure that I'm not supposed to be treating it with something. If there is a natural oil that I should apply, please let me know.


    It is not necessary to treat the tub and usually japanese people do not apply anything.
    In case you want to restore the original shine you can apply our hiba oil with a cloth, like you would do waxing a pair of leather shoes.

    for purchase please refer to:
    http://www.bartokdesign.com/japan/2-products/wood_tub_cleanerconditioner.php
    and for more specific information to:
    http://www.bartokdesign.com/japan/0-blog_news/new_product_hiba-oil.php

    Please keep the tub protected from direct sunlight and if you cannot, leave the tub full of water to prevent dehydratation and cracks.

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    Q #30

    I am measuring the niche where I will be placing the hinoki tub. How precise should the dimensions be?

    A #30

    We build with a tolerance of +/-1mm, anyway be aware that wood is a natural material and tends to shrink and expand with the change of seasons.

    If you place it against a wall, be sure to leave a 10mm clearance all around to ensure air circulation (see details page).

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    Q #29

    Hello Bartok Design,
    I am a specialty contractor in Seattle Washington and a Japanese friend of mine who has a Hinoki Ofuro says that it leaks. I took a look at the tub and all the boards look in good condition, but my friend says that the water leaks between the boards at the seams.
    Your website mentions in the question and answer section that cracks can be fixed, but it changes the asthetics of the tub.
    Does the tub need to be taken apart and resealed or is there a way to stop seam leaks with some other product? Any information that you could give to help save this wonderful tub would be greatly appreciated.

    A #29

    Thanks you for your mail.
    Hinoki tubs do not leak unless there is a crack in the wood.
    Cracks are caused by dryness. They can be repaired with a sealant:
    1) simply clear silicon: it allows movements of wood and it becomes invisible as the crack closes again after normal humidity level has been restored.

    2) epoxy putty: it is water resistant and with color similar to wood. But as it is hard, wood balance becomes altered.

    Another cause of leaks is poor joint construction. There is not much you can do about it apart for caulking all the inner corners (floor and walls.)Use mildew-proof clear silicon.

    It is very difficult to disassemble the tub and most surely you will have to replace some parts. It might be worth the work if you create double tongue/groove rims at every joint but again, the main problem is whether it can be taken apart without damage or not.

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    Q #28

    Dear friends,

    We love our hinoki tub that you built and that was installed in our home about a year ago.

    The tub itself is fine, but the wooden slats on top have developed mold. Is there anything we can do to get rid of it?

    A #28

    For the mold stains, try to use some bleach, it should become clean again. -> http://en.wikipedia.org/wiki/Bleach

    1) apply a small amount of bleach on a dump cloth and friction the mold spots. An old bath towel should be fine.

    2) wipe immediately with a clean dump cloth.

    3) repeat if necessary

    4) rinse abundantly with the shower while wiping with a cloth to remove any bleach left.

    This treatment does not harm the wood if you do it few times a year.

    Also, I recommend to turn over (upside-down) the planks from time to time. This prevents the formation of mold and warping of the planks overtime.

    In case you do not want to use the bleach or if it has scarce effect, the standard solution would be to use a planer. Also fine sand paper will do the job.

    Let the wood dry well and use first fine paper (#240) to remove the wood skin. Finish with very fine paper (#400). Reember to follow the direction of the wood veins.

    Please let me know if it worked out.

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    Q #27

    I also have a technical question: What happens if, due to excessive heat the wood happens that a horizontal crack appears in the floor of the tub? Is this repairable in a manner or another? Please let us know.

    A #27

    (here below we are reporting extracts of the full correspondence for your reference)


    About the the horizontal crack: please send me a detailed picture.
    Is it in the joint between planks or in the middle of a plank?
    How long/wide is it?
    Do you think it leaks water?
    when did it appeared?
    Did you leave the tub dry for long periods?
    Once we see the picture we will be able to give you better advice.


    Concerning the crack, I went back to the site this morning and took some shots I am sending to you herewith.
    To answer your questions:
    - it seems to me that the crack is between two planks
    - it is the total width of the tub's bottom floor
    - it is something like 1mm to 1,5mm wide
    - yes, it leaks water unfortunately
    - it appeared to us two days ago
    - yes we left the tub dry sometimes, and moreover, a week ago we put in service a floor heating that is underneath the tub but also around it. It might have dried the air in the room. Added to a very warm summer here.

    Timing of that problem is quite bad since we were ready for handing over the project to the owner client the 1st of september.
    Thank you for your advice.

    I see: the problem is definately the floor heating.
    In general every heating system in the bathroom is bad for the bathtub. It dries up the wood especially if it runs for many hours a day (like central heating systems).
    Of course it depends also on the width of the bathroom and height of the ceiling, in any case, we recommend to keep an hygrometer in the bathroom and check regularly.
    Floor heating is even worse for the wood tub because the heat tends to concentrate towards the floor and the humidity is washed away systematically as hot air moves upwards.

    I recommend to use an underwater epoxy sealant. It should be pushed into the crack with a spackle, to fill it up completely. You may finish the last 1mm with underwater epoxy putty which has a color similar to wood. I could sent you this material by EMS mail but it takes over a week (now customs are full because of holiday period tail).
    If you need to repair before sept.1 , try to look for this material locally and let me know if you have problems.

    Also, remember not to use the heating when the tub is empty. If you need to, fill the tub with 10cm of water and use the heating without fear.


    Thanks for your detailed answer.

    I think it would be wiser if you send me the underwater epoxy sealant, and the underwater epoxy putty, that you have already used, and that has already given good results.
    If you can do it as soon as possible, and send me the invoice for immediate payment, I would appreciate it a lot.

    I checked with my carpenter and he recommends no putty, just make the epoxy fully penetrate. It has a greish color.
    after it is dry, you can sand or plane it.
    This morning we sent you an EMS parcel. Please let me know if you could fix the problem.


    Thank you very much for your product. We received them last wednesday, and the result seems good for the moment. No more leaks!
    From the aesthetic point of view, the repair is ok. Sure the color is grey and you can see it if you know it is there, but it is not shocking at all. I will send you a photo tomorrow.

    We have not used the hiba oil on the tub yet, but it smells so great in the water.

    bathroom renovation
    Q #26

    Several years ago I purchased a tub from Japan and it came with a container of a kind of cleaning/conditioning fluid for the tub, which included a hinoki oil base.
    Do you offer, or know where I could obtain, something similar?

    A #26

    Cleaning liquid: I am sorry, we do not have this product. In Japan,
    as in other countries, hinoki oil is available for aromatherapy in different formats, including a liquid emulsion to be poured inside the hot water to have a hinoki-tub-like aromatic effect.
    This is not used for cleaning. Hinoki wood contains within its fibers the resinous product commonly known as hinokitiol. Usage of cleaning products such as detergents or waxes/oils will clog the natural wood pores thus sealing inside the hinokitiol. If you want to take maternal care of the tub, you may wipe it with a towel after use which will prevent any darkening caused by mold.
    Then keep a hygrometer inside the bathroom and avoid the relative humidity to drop below 50%.

    UPDATE 2008.08.01
    See also our news and products page. We have now a natural oil extract which can be used to clean, protect and regenerate the tub.

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    Q #25

    how are the modern Japanese recirculating water through a heater?
    Or are they mainly designed for one session of hot water?

    A #25

    Thank you for your interest in our japanese bathtubs.

    The japanese tub is a very simple, low tech, minimalist box made out of wood. For this reason it is also very flexible and can adapt to different uses.

    In our experience, most of the private clients drain it after use. Anyway one session can be extended for a whole day with the use of tub covers and by adding hot water at need.

    Most of the business users add on site recirculating/filtering systems in line with a heater. We do not supply this systems ourselves for the following reasons:
    1) US or european makers of pumps/cartridge filters/ozone systems etc. are more advanced than products available in japan
    2) Considerations about maintenance and spare parts
    3) It is very easy to open a hole in solid wood with the pitch and diameter matching your equipment.

    I hope I answered your question. Our tubs are custom made to fit the particular needs/sizes of each site and most of the solutions are evaluated case by case.
    Please do not hesitate to contact us for any question or problem.

    Please find below a scheme kindly participated by a client. (Wabi Sabi Culture - Pescara - Italy)

    Ofuro Filtering System at Wabi Sabi Center.jpg

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    Q #24

    My builder also enquired if it would be possible to get something like a VAT registration statement in respect of Bartok Design in Japan, if such a thing exists in Japan (it can be in japanese, I can get it translated locally). Or is this information going to be contained on the invoice? This is becase - I assume - since the tub was produced for export, there would have been no VAT or equivalent sales tax chargeable in Japan, but it will fall to be paid by me once I take the house with the tub in it from the builder. The builder would like some sort of documentation to support this.

    A #24

    I understand what you are saying (a stamp stating that the shipper is VAT exempt is required for exports originating in Italy), anyway the japanese customs do not require it.
    The shipping is DDU terms (Delivered Duty Unpaid) which already implies that VAT is payable by the coinsignee. On nearly one hundred of shippings we were never required to provide this declaration so to be honest I am not sure how to make it.
    Of course I can add a "VAT unpaid in country of origin for exported products" declaration and send you the amended invoice. Is it enough? Do you have any specific requirement according to the format of this declaration?

    UPDATE: 2009.05.02
    Needless to say that for business users, VAT is paid at the customs ad then refunded or in some cases it is voided when you provide your company information (eg. Belgium). This makes a huge difference for countries with a high VAT (Scandinavian Counties, Belgium, UK and Italy)

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    Q #23

    May we use credit cards?

    A #23

    updated on 2009.4.27.
    Yes, we will accept payments thru PayPal.

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    Q #22

    We are looking into your tubs for a remodel in the state of New York in the US. The building inspector has told us that the tub needs to have ASME plumbing approval (American Society of Mechanical Engineers). Do the tubs meet this standard? Can they be made to?

    A #22

    Thank you for your interest in our hinoki products.
    Sorry, we do not have an ASME sticker. We had 2 cases in the past of exports to Canada requiring a CSA sticker. I think that the client explained the details and could convince the inspector.
    This is the first case I hear of such a requirement for the US.
    You should keep the line that a hinoki tub is not a hygenical fixture (bathtub), it is rather a health equipment (soaking tub). We are at your disposability, should you have any problem.

    UPDATE 2009/1/1
    We had two more cases in the US of the building department requiring ASME approval. (California and NY State). In both cases it was explained that the tub is for soaking (like a hot tub) and not for washing. This solved the problem.

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    Q #21

    The shipper told us that the customs may require what they called a PHYTO Certificate. It was explained to me to be a declaration by the producer of the imported goods which type of wood the product is made of, that the wood used was not treated by any dangerous chemical substance and that it is free from pests. Have you heard of such a requirement before?

    A #21

    As the tub is a manufactured wood product, you should not be required for a Phyto certificate. Anyway we will be glad to supply a declaration stating the origin, treatments and properties of the lumber we employ. Please see here a sample -> PHYTO CERTIFICATE


    ADDED 2009/3/12
    In recent years there there has been a strenghtening of the rules concerning packaging (crates, boxes). Shipments to Australia, China should be done in non coniferous wood crates otherwise they will be fumigated.
    On the other hand, shipments to California cannot use plywood crates due to a very recent restriction on products containing formaldheide.
    In any case, we receive constant updates from our forwarder so you will not have to worry about this matter.

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    Q #20
    I visited your website. I really like the look and healing properties of your tubs. And, the craftsmanship seems outstanding. After reading about the hinoki wood and the few places it can be found, I was curious if the hinoki wood you are using is farmed or old wood. Is there concern about depleting it? Here in the Northwest United States much of our cedar is gone -- to the point of great environmental concern. I know Japan is protecting its forests as well. I'm curious about the current situation with the hinoki species.
    A #20
    We use both cultivated and natural wood. It depends on the type of project, size, quantity etc. In any case, all the wood comes from sustainably managed areas, some are FSC certified (FSC tands for Forest Stewardship Council). Hinoki is a coniferous tree and the growth takes about 20-25 years before being commecially exploitable. Farmed wood has the advantage of having few or no thru knots for an optimized usage of the material.
    Japanese farmed coniferous wood is a story with lights and shadows. Back in the 60`s and 70`s, millions of acres of mixed aboriginal woodland has been destroyed to make space for the more commecially exploitable farmed wood for construction. To add insult to injury, during the 1990`s a weak dollar promoted imports of cheap 2x4 material from Canada, so that japan forestry entered a deep crysis. After overproduction caused a drop in price, many forested areas ceased to be maintained or were abandoned all-together. This created a new problem: man-made monocultured-crop forests are not stable ecosystem and the lack of maintenance causes landslides and other disasters. The bottomline is that there is no point in crying over the poured milk: now the only thing we can do is to use this overstocked farmed wood to bring some relief to the mountain problems and maybe end up saving also some north american cedar forest (or what is left.)
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    Q #19

    May I ask why the corners of your tubs are 'T' shaped? Can you make mitred joints?

    A #19

    While hinoki is impermeable when cut parallel to the wood grain, transversal sections are 6~8 times more vulnerable to water infiltration.
    The traditional joint allows for full coverage of the plank head. Also, plugs and SUS screws can be inserted deeply in the joining plank, making the tub extremely solid and durable.

    No, we will not make 45° mitered cuts. It is a weaker joint and is not a proper detail for a hinoki tub. I wish that tubs with mitered corners were not misleadingly called "Japanese tub"...

    UPDATE 2008/06/20
    We developed a model of tub which retain the constructive traditional details while providing an clean "minimalistic look". This was achieved with thicker wall planks. See also the examples below:
    http://www.bartokdesign.com/japan/7-custom_ofuro/hinoki_tub_for_surrey_2.php

    http://www.bartokdesign.com/japan/7-custom_ofuro/hinoki_tub_for_manhattan.php

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    Q #18

    Is it possible to have the bath fabricated from Teak wood? If not..which wood that you use wood look good next to teak..perhaps with a stain to bring the wood darker and closer to the Teak?

    A #18

    Our company is specialized in japanese hinoki wood and other softwoods of the cypress family such as sawara or asnaro-hiba. We will not build a tub in teak or any other imported hardwood.

    If a tub should ever be built in teak, it should be uretan coated as it would produce an unpleasing smell and anyway it has not therapeutic properties.

    About staining hinoki: again, one of the main points of having a japanese wood tub built is the aroma and the natural feeling of untreated wood. By using a stain, these 2 elements would be spoiled.

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    Q #17

    Do hinoki wood tubs leak?

    A #17

    Hinoki tubs do not leak but may weep when the water is kept inside for a long time or due to condensation. Waterproofing of the floor is not required, but recommended. Anyway I would suggest to use materials such as stone or tiles under the tub.

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    Q #16

    The tub was delivered yesterday.
    Thank you ever so much for everything again.
    We, however, made a few mistakes and I would like therefore to ask you for some additional advice.

    First of all, we forgot to read the paper attached to the plastic cover of the tub (we were so excited, like little kids, to open our present !!!), we realised afterwards that we should have left it wrapped in, since the bathroom is not yet ready. What should we do (humidity level, dust etc.) ?

    Also, there was a small accident while opening the crate. The damage I mentioned to you on the phone was only on the crate, and there was no trace of damage on the tub itself, so that is resolved. However, we used a hammer to loosen the side boards of the crate, and the hammer must have rebounced and hit the top edge of the tub on both sides, at the height of the brand. I'll send you the pictures when I get them on my computer from my neighbour. That means that we will probably have to sand down the whole top of the tub all around to make the marks disappear. Is that the right thing to do ? Are there special instruction for that matter as far as making the slanted edge, and/or treating the wood once sanded ? Is the wood treated, or is it only treated at the bottom ?

    Everything would have been perfect, were it not for our impatience and uneducated use of that hammer...

    With my warmest regards,

    A #16

    Please note:

    1) for the plastic wrap, if it is still usable, wrap again the tub and use generously wide tape to seal the openings
    If the wrap is badly damaged, you should get some new one from a home center. Close with tape.

    2) For the hammer marks: I will need to see the pictures.
    Wood swells when it is wet and there is the possibility that it slightly returns back if you blot it with a wet cloth (not just dump, make it dripping wet) or by pouring water on it for at least 1 hour.
    If the wood is not returning, you can apply the dump cloth on the damaged area and press it with an iron (cotton-high temperature, apply intermittently for few seconds).

    A third option is to sand it. The wood is not treated (excepted for for the bottom plank head). I think you should be able to sand only the faces which are damaged and not the whole top.
    The corner fillet (mentori) should be made with a hand plane but this tool is difficult to use. You may employ a sander but be aware that the corner will become roundish instead.

    bathroom renovation
    Q #15

    Which is the optimal humidity level for a wood tub? Can I use one for outdoors?

    A #15

    You should pay attention to the following:
    The wood is a natural material and is well preserved in a balanced environment. A moisture percentage of 50% is recommended.

    • If there is scarce ventilation and the humidity is often over 70% your tub is likely to develop mold stains (which can quite easily be removed)

    • On the other hand, if the environment is too dry (below 40% relative humidity) the tub may crack and cause leakings.
    The dryness effects can be mitigated by using the tub daily or leaving it full of water when you leave home for longer periods. Dryness is harmful for wood. Avoid direct and prolonged sunlight exposure and if you have heating system in the bathroom, keep an eye on the hygrometer.

    Yes, you can install the tub outdoors, but please avoid as much as possible direct sunlight exposure, expecially when the tub is empty.

    bathroom renovation
    Q #14

    Are your japanese hinoki bath tubs mold resistant? How do I clean it?

    A #14

    Hinoki wood has a unique natural protection against rot, mold and fungi, but you should use some common sense. If the bathroom is not ventilated or if you leave the bathtub full of cold water on a daily base, some stains may appear overtime. No need to worry. Just pour abundant warm water on the area until well absorbed by the wood. Then wipe gently with a cloth sprayed with alcohol for disinfection. The stain will disappear completely.

    ADDED 2009.04.22
    For toughter stains you can use -wisely- also some bleach for clothes. Wash abundantly with water after application.

    bathroom renovation
    Q #13

    How long can I leave the water inside the tub? Do I need to dry it after each use?

    A #13

    The water should be removed when all the members of your family enjoyed their bath. Of course you can leave the water inside until the next day but unless you live in a very dry area, leaving water all the time of course can facilitate the insurgence of some mold stains.

    Anyway, best practice is to empty the tub everiday (or at least twice a week if you have a recirculation system), quickly wipe the bathtub with a towel to remove the excess water. Then ensure there is a good natural ventilation (a bathroom with a vindow is strongly recommended) so the wood can adjust automatically its degree of humidity.

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    Q #12

    What kind of payment schedule is common for the purchase?

    A #12

    Every tub is made to order. We will require a 50% deposit (made by wire transfer to our bank in Japan) to confirm the order. The 50% is calculated on the price of custom made items. Within 30 days we will build the tub and send you by email the photographs of the complete tub / accessories.
    Then we will require the balance 50% payment + packing charge + accessories if any (es. bucket, chair...) + transportation charge, as it was shown on the quote.
    If you prefer you can use a forwarder you know and we will omit the shipping expenses.

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    Q #11

    Is the cost inclusive of transportation?

    A #11

    Yes. Each personalized quote includes pick-up in Japan, freight, terminal charges and delivery up to your door (unless you specify otherwise).
    The price may not include sales taxes. In most cases you (the coinsignee) will have to fill in a customs application (it can be done by fax) which costs 200-250 US$ and includes sales tax. You will not have to pay any other charge.

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    Q #10

    Can you ship to the United States? How long does it take?

    A #10

    Yes, we do ship to the US and to many other countries worldwide. In most of the cases we use air freight. Once the order is confirmed with a deposit, we start to custom build your bathtub. We guarantee the delivery to your home in 6~8 weeks from confirmed order. Shipping is done in a sturdy wood box and it contains the bathtub unit already in one piece for troublefree installation.

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    Q #09

    Do you only make ofuro, or do you also provide disinfection systems, recirculation pumps, and everything I need for a commercial ofuro?

    A #09

    To be honest, building a tub is more similar to naval carpentry than a normal plumber job. We do not supply any machine or pump equipment of any sort.
    I recommend to find locally a pump and cartridge filter. If you replace the water every 3 days or so, you might skip the filter. About the disinfection: do not use chlorine.
    Ozone seems to be popular, personally I would recommend a salt chlorinator. Please ask a pool equipment dealer near you. I had a client who used 'Aquapure' in a small pool and was very satisfied. It is a product available in the US. See: http://www.jandy.com/html/products/chlorinegenerators/aquapure_faqs.php

    bathroom renovation
    Q #08

    Your site recommends 'pure warm water' Is a high salt content okay? My image is the salt pools I sat in at Spa LaQua. I am thinking of Israel Dead Sea Salts, or another healthy salt.

    A #08

    There isn`t any direct problem about using salty water in a hinoki bath as long as:
    1) once tub is emptied, it should be generously washed with normal water to avoid oxidation and staining
    2) we will use stainless screws and plates, so no problem.

    Anyway we do not have experience of this and do not know what it will happen in the long span. It may be OK, I do not know. You would have to try at your risk. I feel that salty water would at least alter the aroma and therapeutical properties of hinoki, but this might be just our prejudice.

    bathroom renovation
    Q #07

    Do we need to adapt the diameter/length of the fittings? We are planning to use a circulation pump.

    A #07

    You have to think of the hinoki tub as a large basinet. It is simply set on the floor and not connected with any piping (a part for the case of a pump). The faucet is wall mounted and the water flows into the tub. Often the drain is not even connected with any fitting: the water flows out from the bottom towards a floor-drain.
    For the pump fittings: you can let us know the exact location of the outlet and inlet so we can prepare the openings.
    Actually, opening the drain hole (of the right size, in the right location) on site is the probably best option as the tub is made of solid wood and opening the hole is very easy.
    We do not have availability of fittings with diameter/threading matching the connections of your pump. You should request the pump manufacturer fittings at least 3" long. (the tub wall is 42mm thick). In the worst case, you should be able to have fittings custom made in your country.

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    Q #06

    I would like my bath tub equipped with a circulating pump.

    A #06

    Sorry, we cannot supply from Japan heating / filtering / circulation pumps or whirpool systems. Maintenance or replacement of parts would be too troublesome and expensive. You should find one locally and send us the pump specs so we can modify the bath-tub as required. Please note anyway that in most cases a pump is uneconomical and unpratical for private use.

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    Q #05

    I am looking at your rectangular ofuro.
    What is the life span? I am concerned that due to its rectangular shape, over time, the water pressure might cause leaking at the seams.

    A #05

    The life span depends very much on the site conditions and care in using it.

    A wood tub is built to last 30 years and over of daily use: anyway the average life span is about 10-15 years.
    The problems are not caused by water pressure, as we dimension carefully the thickness of the planks and the joints are extremely solid.
    If the ofuro is wider than 800mm we use a top beam frame construction.
    The causes of aging come from humidity level. If it is too high, it can create stains or mold. If the room is to dry, the wood might crack. Of course cracks can be repaired, but the esthetics is compromised and after 10-15 years many decide to replace the tub.
    Keep in mind anyway that ofuros in commercial spas or hotels in japan thus are heavily used, have a long life span because are well mantained.
    If you check periodically an hygrometer and keep the habit of quickly wiping the tub after every use with a towel, your tub will be strong and even more splendid after 30 years.

    Here to the right is the side board (against the wall) of a 15 years old tub we just replaced in a hotel. Considering that it could not be accessed for cleaning, it is still in good condition after all this time!

    bathroom renovation
    Q #04

    I live in a dry and hot climate. Will my japanese hinoki bath tub suffer damage from this conditions?

    A #04

    The japanese hinoki is a very tough wood. It is compact, stable, hard, insect and mold resistant. It does not crack in conditions where other woods crack and does not mold when all woods usually rot.
    But it is still a natural material and it is always better to avoid extreme conditions. It is ok if you use it at least once a week.
    If you leave your house for a long period follow one of these direction:
    1) fill your hinoki tub with 5" of water and leave uncovered.

    -or-

    2) leave a basinet containing water inside and cover the tub with its lid.
    -or-

    3) Wrap the exposed sides and top of the tub with clear poliethilen film. Close gaps with tape.

    Avoid direct permanent sunlight exposure, expecially when not used. If you keep it always full, you might want to empty it once or twice a week and let it dry for 12 hours.

    bathroom renovation
    Q #03

    Does knotty hinoki last as long as the smooth one?

    A #03

    The knotty and smooth wood have almost the same performance. Should they were to be tested in a laboratory, you will find out that the straight cut hinoki is maybe 10% more resistant than the knotty one. But this is rather an academic problem. You will avoid anyway putting the hinoki in extreme conditions and will enjoy it for 20 or 30 years.

    It should add that the knotty hinoki is slightly (again, about 10%) more aromatic than the straight one as knots tend to be rich in resin.

    bathroom renovation
    Q #02

    Are your bath tubs made in Cypress Hinoki wood? Are they made in Japan?

    A #02

    Yes. All our Hinoki comes from the Kiso Valley (Nagano prefecture, Japan): the most precious hinoki production area. Since the 1950`s all tree cutting is done in respect to the environmental sustainability and is subject to strict rules.
    Yes. all our bath tubs are handmade in Japan by our skilled "toyo" (master carpenter) using traditional techniques.

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    Q #01

    Hinoki the same wood as Port Orford Cedar?

    A #01

    No. Can you say that a filet mignon is the same of T-bone steak? Port Orford Cedar, also known as Yellow Cedar, is an appreciated North american wood used for construction and sidings. Anyway, Hinoki (or cypress hinoki) has higher rot resistance and more pleasant grain and color. Moreover, the soft aroma of the Hinoki wood is much more pleasant than the strong smell of the Port Orford Cedar, expecially when warm water is poured on it. For this reason, we may suggest the use of Orford Port Cedar for the wall paneling of the bathroom, but we do not recommend to have a bath tub or the floor duck boards built with this wood.

    bathroom renovation
    Q #00

    please use this page to post your comments:

    (for any specific or urgent request, please emai us at japan[at]bartokdesign.com)

    A #00


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    questions and answers about japanese hot tubs, mainenance and hinoki wood qualities