Varnish -- Urushi Lacquer

[Gamma]

The FDA has, over the years, not exactly been a bellwether of accuracy, credibility, or reliability.
Not everything is compiled into modern data forms. Subtle intricacies of many old art forms are, often, passed on 1:1 via discussion and not via spread sheets or found posted on the internet. .
Cured urushi has caused irritation in hyper-sensitive people. Long-term artisans willing to discuss their craft at this level will tell that the chance of that happening may be small, but it is there.
I've used Hon Urushi with several solvents in varying concentrations with and without (for lack of the correct terms at the moment) bottom and top coats.
It's finicky, but lustrous when cured. For me though, without a larger area, the effect is lost. But the aesthetic remains, for whatever that's worth. To me it's more labor intensive than I have patience for. The end result is not 'the bomb' so I can use other products and be just as happy.
I use a bit of Cashew Lacquer here/there, it suffices for me. But I might give Hon Urushi another spin someday - maybe.

 

[Hunter Bock]

That no one has come forth on using Urushi for scales may be telling. And no one has reported failure with scales either. Seems we’re pretty much on uncharted turf with Urushi scale finishing.

I’ll use this post to offer a summary of what I’ve gathered along with some direct lifts from various sites (italics) that I found useful or intriguing.

Pure (raw) Urushi is the most intense product with gloves/mask/long sleeves advised. For use on wood the most popular forms are Shuai and Seshime. The former yields an amber-neutral finish while Seshime is more brown.

It’s the sap from a tree. It’s that simple. But there is a caveat. This tree, Toxicodendron vernicifluum, and its sap contains the compound urushiol. This compound, urushiol, is also in poison oak and poison ivy among a few other plants. It’s the urushiol that’s the key. When exposed to high humidity an enzyme is activated and extracts oxygen from the water and supplies it to the urushiol. The urushiol solidifies or polymerizes, forming a hard film. Even after it’s hardened, the urushi retains some of the original water, making it look perpetually wet and shiny. Fully hardened Urushi lacquer is very stable and strong. It is able to withstand alkali, acid, and alcohol, and also being able to resist temperatures of over 300 C - 570 F. It is also resistant to molds and mildews. It does have weaknesses…it can be degraded by UV rays from the sun and other sources or extremely dry conditions. The draw back for such a perfect natural finish is that contact with the uncured sap creates contact dermatitis. Most of us have had or seen a reaction at one time or another from contact with poison ivy or oak. You can do a quick internet search for some brutal images. There are a few among us that are immune to the effects so count yourself lucky if you fall into that group.

Outside Japan the Urushi tree found only in South East Asia and the Korean Peninsula. There may be non Japanese resources and practices that I’ve missed here.

There are alternatives -- likely the best way for beginners. Mejiro Low Allergy Urushi and Toho Lacquer (part Urushi) were referenced earlier. Faux Urushi finishing is possible with synthetic lacquers -- Washin Paint Aqueous Crafts Lacquer, Urushi Clear and Cashew Lacquer being frequently mentioned.

Did get some feedback on EarthPaint’s Mountain Wood Finish (cashew based) : I use earth paint, the mountain finish stuff. It’s an art applying this stuff. Something I’ve slowly been getting better at. The key is super thin coats. 1 pint of this stuff will last 10 of us 10 lifetimes sealing just stones. After I seal them I have to put a box over them to let them dry.

EarthPaint (Asheville NC) doesn’t get any points from me on communication. Maybe their not responding is a covid thing.

The technique that sounds most promising for wood scales is Fuki Urushi, where the lacquer is applied with a brush and then rubbed into the wood with a cloth --

The method I was shown was called fuki urushi. It uses a type of urushi lacquer called seshime which is dark brown in color. After wiping the wood with a dust free cloth you brush on a thin coat of seshime then wipe it off. We use a special type of cloth for this that doesn’t leave it’s fibers behind like a paper towel would. We then put the freshly lacquered object in a muro. This is a wooden cabinet that has been set up so that the humidity and temperature can be controlled. Japan is a humid place, especially in summer, so curing is easier there. Once you understand this it becomes easier to understand just how the finish was first developed all those years ago. Did I mention that was 8000 years ago?! I’ve heard stories that during the summertime lacquer artists try to take advantage of the ideal conditions for curing and plan on getting a lot of work
done. In our muro we use humidity and heat controllers that are marketed for folks that have pet reptiles. Once in the muro we leave the coated object for at least three days with very strict climate control of 75-85% humidity and temperature of 70-80F. I like to put on 3-5 coats, so to complete the process can take weeks.
______________________________________________

In this technique [Fuki] the wood itself is impregnated with the lacquer. The natural gleam highlights the beauty of the grain of the wood. Akira Murayama is one of the leading wood craftsmen. And he is recognized as a living national treasure. Most of his work is called Fuki-urushi.

This is how the Fuki-urushi technique is implemented. First a coating of lacquer is applied to a piece of wood using a brush. The urushi is wiped thoroughly with a cloth to ensure that it has been applied evenly. Allowing the wood to soak up the lacquer helps to make the pattern of grain stand out more clearly. The surface is then carefully polished with sand paper. This entire procedure is then repeated 5 or 6 more times.

The coat of urushi is applied, and then polished, and sandpapered -- Repeating these steps ensures that the simple natural beauty of wood is seen at its best. The entire process can take months to produce a single piece. [Murayama] tries to listen to the voice of the wood, as he works it.


Curing is an issue for any lacquer with Urushi content. For those without a high humidity pet I think the use of a cigar humidor or mason jar with a humidifier disc might be worth experimenting with.

I’ve avoided any discussion of specialized brushes or cloths as this pertains more to crafting Urushi lacquerware. The specialization and varieties here are dizzying.

Lacquered woodenware is very common in Japan. Most everyone knows it. In fact you can find it in department stores sitting alone aside plastic bowls. It’s a weird sight, but true. We returned with a few bowls and cups and we’ve been using them at least once a week if not more. The more they are used the more rich the finish gets. Slowly it becomes more transparent revealing a layer of colored lacquer underneath the top layers. It’s really amazing.

It’s worth exploring Urushi on YouTube.


For any Orientalists out there : The word “urushi” comes from two other Japanese words: “uruwashi”, meaning “beautiful”, and “uruosu”, which means “to moisten”. For those of you who enjoy kanji, it is interesting to note that the kanji for urushi (漆) is unique in that it is perhaps the only tree kanji which does not have the tree radical (木) prominent on the left side, such as “桜” for sakura (cherry blossom) and “楓” for maple trees. Instead, the radical for water is there (氵), which emphasizes that the tree is valuable not so much for its wood, but its water, or sap. To remember the right side, you can use the following mnemonic: when a tree (木) is cut (symbolized by the upside-down “v”), water (水) comes out.


So are the results potentially worthwhile? I think so but am not going to get into repartee with anyone as I haven’t tried anything Urushi related yet. Noting the many caveats offered in this thread (risky, takes too long, difficult, few doing it now, results not worth it) I can only observe the same has been directed at straight razor shaving.

The drivers and passions of Urushi are surely individual and subjective. Reminds me of a couple of books :

Amazon.com

Amazon.com

Thanks to all who have contributed here.

 

[ajduplessis]

Interesting thread but something I will give a pass, there so many other safe options to finish scales.

Good luck and share your progress.

 

[LJS]

Just go do it. You certainly seem like you want to You could have bought some, used it, gotten your prednisone shot and been back to report by now LOL

 

[Hunter Bock]

In the works but not soon LJS. If I get a Quasimodo skin reaction I'll send you pics .

 

[LJS]

In the works but not soon LJS. If I get a Quasimodo skin reaction I'll send you pics .

I’ll pass on that too LOL! I know toxicodenedron here in the US all too well Luckily I’m not too sensitive to poison ivy like some folks are, but one winter when I was about 10-12 years old I helped my Dad who was cutting down a bunch of pine. He was cutting and I was in charge of the burn pile which was awesome for my age. Unbeknownst to either of us all of those trees were covered in poison ivy and I learned the hard way that those compounds volatilize in fire and travel with the smoke. Nothing like poison ivy on just about every inch of your body including mouth eyes etc Yes Sir, will Not be forgetting that life experience!

I do realize this is a different species, different material, etc etc, but this does sound like something you should do in a hood vent. I doubt any finish on scales is worth your health. Just be careful.

There are a lot of excellent alternatives.

 

[Hunter Bock]

LJS -- haven't decided whether to try pure ($$$ and ordered from Japan) or a reduced version. Curing time will be weeks; won't be getting anything to the forum soon.

When I was a kid--back in the Pleistocene--I could rub poison ivy on my arm without any ill effect. Wouldn't attempt that today. Will exercise due caution and post results, positive or otherwise, in the upcoming months.

Did get some more feedback after my post:

I think seshime would be better. But its about personal tastes over anything else. I think the urushi with oil added doesn’t look as good.
Thin the 1st coat 50/50 with turpentine. Brush on wipe off, cure. I’d say 5 coats. Other coats can be full strength. The visual appearance changes with number of coats. Maybe you’ll like 3...maybe 5? You’ll have to find out.
Lightly sand in between coats with water and 600 grit. Always wipe down with with turpentine before applying. Oils from you hand can prevent lacquer from curing.

Just finished the Adamson book -- maybe that's what has fired me up.

Hang in there.

 

[Hunter Bock]

2021 Update: still waiting for Dec. Urushi order from Japan. Increasingly it looks like I will need to attempt recovery of payment and order again. So no projects to report.

I was able to establish contact with EarthPaint (referenced earlier). Their cashew resin (Mountain) is a very distant relation to Urushi but just might be the thing for those wanting to simulate.

Per EarthPaint:
We cannot detect any trace levels of urushiol remaining in our cashew resin. So, to me removing that toxin is the biggest difference. Mountain is the only of its kind, behaves like a urethane and can create gorgeously lacquer finishes. It's made from cashew and Citrus so we leave any nut allergen warnings on just in case, but haven't had any reported issues since we reached untraceable levels of urishiol (and other extractives) many, many years ago.

 

[Ad Astra]

Urushi is also used on the stocks of Japanese rifles from WWII called Arisakas.

Veterans refinishing their war souvenirs frequently got the poison ivy surprise.

Can affirm its hard and beautiful... And I leave it undisturbed.


AA

 

[Sukeroku]

Urushi has been used for almost all traditional soup and rice bowls before the advent
of plastics. It still used in high-end restaurants and in tea ceremony utensils. Cured urushi
vessels are safe even with hot soup. That said, it is notoriously difficult to work with.
Urushi artisans are even rumored to drink the weak concentrations stuff in order to develop
a tolerance (do NOT try this at home). I may try to find an urushi artisan to make some scales
for me. I am putting together a set of Japanese quarter hollow razors for a 7-day set. They would
look amazing if I could outfit them with urushi scales and a paulownia box.

 

[Steve56]

I’ve used the Earthpaint product. I does have cashew in it but the second ingredient is linseed oil. It’s quite thin and clear, intended for floor use, and seems to act more like linseed oil than cashew. I prefer marine spar varnish to it. Spar varnish isn’t traditional, but it looks traditional and it works well. If you don’t tell anyone they won’t know.

I’ve only used hon urushi on one stone so far and it’s fine, but cashew is easier to get and easier to use. Hon urushi, as mentioned, is basically poison ivy sap. You don’t need a mask unless you’re heating mass quantities of it or burning it. You do need to have your hands and arms covered, and watch for any skin contact. If you do get some on you, a paper towel dampened with lacquer thinner and followed by copious amounts of soap and water has worked for me the one time I had any skin contact. I am not particularly sensitive to poison ivy if I get it off within say 15-20 minutes, but if I ever do break out with a rash, it’s usually there for a week.

Cleaning the brush is usually a bigger hazard than using the material on whatever it is that you’re lacquering, so be careful doing this.

I agree with Keith that the ROI on scales is probably to low to be worth it, but experiment with cashew first and see what you think.

 

[Frank Shaves]

Perhaps off topic. I was not able to find cashew lacquer at the end of 2020, so I used MinWax Clear Lacquer (in an aerosol can) and am very happy with the results:

Minwax Clear Brushing Lacquer Finish & Aerosol Lacquer | Minwax

It's readily available, inexpensive and really easy to apply. I just compared a stone with cashew lacquer with a second sealed with the Minwax. My eyes cannot see a difference, and they feel similar. The cashew lacquer may feel a tad softer.