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Help with Shellac...

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Forum topic by Grayswandir posted 07-16-2021 09:26 PM 1700 views 1 time favorited 15 replies Add to Favorites Watch
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Grayswandir

17 posts in 257 days


07-16-2021 09:26 PM

Topic tags/keywords: help shellac cut waterproof moisture wood zinnser question

Hello,

I’m an amateur when it comes to wood finishes. I have some Zinnser shellac, but so far I’ve been unsuccessful, or rather not completely satisfied with the results I’m getting.

Let me start from the beginning.

I acquired an old barbers hone. The hone had a sticker on the side of it that I wanted to preserve, so someone recommended I coat the sticker in shellac. I needed to lap the hone flat to remove a few chips from the surface and make sure it was flat for razor honing.

In order to lap the hone I had to use water (to carry away the swarf and make honing easier), and water would have destroyed the old sticker on the side of the hone/stone. I applied a few coats of the Zinnser shellac. It was quite thick and never really dried fully. The end result was a coating of shellac that acted more like a clear rubber coating then a hard finish.

I learned a little more about shellac and found out I could cut it with a solvent. I had acetone on hand so that’s what I used to cut it with. I made a little wooden handle for a chuck key that went to my Foredom clone and tested the cut shellac on the handle. It worked a lot better then the uncut Zinnser and dried to a hard finish.

Anyway, I needed to coat a diamond plate attached to a piece of oak (3”x2”), so I decided to use shellac again, as I was pleased with the finish on the wooden chuck key handle. I mixed a small batch of the cut shellac, 5 tablespoons of acetone to 3 tablespoons of Zinnser shellac.

I’m still getting a slightly rubbery finish, though I think it will harden up over the next few days as more solvent evaporates from the shellac. Was acetone just a poor choice to cut the shellac with, or should I have cut the shellac more, say a ratio of 7:3?

The more solvent I add, the quicker the shellac will dry, correct? Is there a more suitable finish I should be using, or it just personal preference?

If I was making a set of knife scales from wood, what would be the best finish, especially if the knife would be in contact with water often? Would shellac be hardy enough, or is there something more suitable? I want something that will bring out the beauty of the wood and withstand a lot of moisture.

Thank you,

-grayswandir.


15 replies so far

View wildwoodbybrianjohns's profile

wildwoodbybrianjohns

2849 posts in 838 days


#1 posted 07-16-2021 09:36 PM

You cut shellac with alcohol, 96% or better, not acetone. I make my own shellac and use a ratio of 1 liter alcohol to 120 grams flakes, or 1:12. Or, 1/2 liter to 60 grams flake, for small batches. Thats about a 1 – 1.1/2pound cut. If you are going to be cutting zinser product you should do tests on scrap first. There is shelf-life for the canned stuff, the older it is the more problems you may have.

Note: I always! keep shellac mixes in GLASS jars with tight lid. Mason-jars are perfect.

I defer to someone else on the scales question but personally, I would use marine varnish and cut it with mineral spirits, in multiple coats, if I was aiming for tough and water resistant. Some will recommend cutting with naptha, also good.

Like so: 1st 75/25% MS/MV, then: 50/50%, then: 25/75%, then 25/75% coats until I had the thickness I want. Sanding after every second coat, then before the last coat, then the final coat should be like glass-smooth when cured.

Shellac is very easy to use once you get the hang of it. Keeping a wet-edge is the trick. If you have problems with holidays or lapmarks dont fuss with them while the shellac is tacky. It will all even out on the next coat, as the fresh alcohol will reactivate the previous coat some and it will blend.

-- WWBBJ: It is better to be interesting and wrong, than boring and right.

View Aj2's profile

Aj2

4146 posts in 3089 days


#2 posted 07-16-2021 10:21 PM

I hate the stuff in a can Never seems to get as hard as freshly made from flakes or buttons.
Brian John is right use denatured alcohol with shellac. Take precautions with denatured it’s really not that good for humans. It might even cause drain bamage. :)

Here’s what real shellac looks like. And it gets harder then Chinese arithmetic
Good

-- Aj

View wildwoodbybrianjohns's profile

wildwoodbybrianjohns

2849 posts in 838 days


#3 posted 07-16-2021 10:30 PM

Oh yeah, Paul Sellers has a very good youtube on how to use shellac.

Link. About 30min long.

https://www.youtube.com/watch?v=UssYj-98oCg

-- WWBBJ: It is better to be interesting and wrong, than boring and right.

View Grayswandir's profile

Grayswandir

17 posts in 257 days


#4 posted 07-16-2021 10:58 PM

I saw some blonde shellac flakes on Etsy for sale, but they seemed a little pricey. I did find another source that was cheaper (a gentleman from India) but I think I’d have to by a half pound minimum.

I appreciate the advice guys.

May I ask why acetone shouldn’t be used to cut shellac? I was aware that denatured alcohol was the go-to solvent to cut shellac with, but is there something negative in regards to using acetone, or are we just following conventional wisdom (tried and tested)? I like to use what I have on hand if possible, but if it’s a bad choice, then I’ll stop using it.

I was thinking about using marine varnish in the future. Some guy on one of the knife forums seals his natural whetstones with a spray can of marine varnish and it seems to work really well for him. A lot of people want to use the cashew varnish like they do in Japan, but it’s really expensive and there’s nothing overly special about it.

I should have thinned this batch a little more, it seems like the thinner the shellac, the less problems that crop up (with small projects anyway), and it dries much faster. I can deal with it drying faster since I’m working on small pieces.

I think I’ll buy some shellac flakes when I have the extra money. I do like how the shellac looks. It really brings out the natural beauty of the wood. I did learn an interesting lesson in regards to shellac and bubble wrap. Apparently bubble wrap will destroy a lot different natural finishes (due to off-gassing). I had that barbers hone wrapped in some bubble wrap and it softened the shellac and left marks in it as well.

Apparently a lot of vintage guitar finishes (nitrocellulose) have been ruined by people shipping them wrapped in bubble wrap.

Thanks guys.

View Aj2's profile

Aj2

4146 posts in 3089 days


#5 posted 07-17-2021 01:13 AM

I buy shellac from the shellac shack. https://www.shellacshack.com/
Remember the best looking shellac finish in my opinion is many many barley perceptible coats. 15 or 20 very thin coats padded on.
I didn’t even know acetone would dissolve shellac seems weird. Ammonia will completely destroy it.
Good Luck

-- Aj

View wildwoodbybrianjohns's profile

wildwoodbybrianjohns

2849 posts in 838 days


#6 posted 07-17-2021 09:18 AM

With most finishes, it is layer upon layer upon layer. Even with oil finishes. With shellac, because the fresh alcohol reactivates the previous application, you will essentially have just one coat no matter how many times you apply it. And the stuff will bond with just about anything. M+Ms chocolate candies are coated with shellac to keep them from melting. This is why it is ideal for wood treatment, the finish wont crack or peel away from the wood, as may happen with Poly or Varnish.

You can cut shellac, like a Zinsser product, with acetone, some will thin it with nail-polish remover (acetone). It will work fine for disolving flakes.

You can also use alcohol like Ever-Clear straight out of the bottle.

Acetone is better, healthwise, as it is not very hazadous, and your body actually makes it. With those who specialize in french polishing, they mix some acetone into the shellac/alcohol mix to get a faster build. this is very common with Luthiers.

Alcohol is used because it maintains the best flow-rate and drying time.

Needless to say, perhaps, but you dont want to be getting any solvents into your skin and/or breathing them without proper ventilation.

Shellac flake may be pricey, but a little goes a long way, and alcohol or acetone is dirt cheap.

-- WWBBJ: It is better to be interesting and wrong, than boring and right.

View Lazyman's profile

Lazyman

8321 posts in 2678 days


#7 posted 07-17-2021 12:11 PM

As mentioned, shellac has a shelf life. The rule of thumb for the stuff you mix yourself is about 6 months. Zinsser does something to extend that to about 2 years (or is it 3?). When it starts to go bad, it acts just as you describe. It either takes forever to cure, instead of about 30 minutes, or just stays gummy and never really cures. High humidity can also have a similar affect. Perhaps the acetone helps to revive it? Zinsser used to put a manufacture code date on the top of the can so that you could figure out how fresh it is before you buy it but the last time I looked, they do not do that any more which is when I finally started buying the flakes and making my own. I mix in 8 oz batches so that it doesn’t go bad on me before I use it up.

BTW, to test shellac for freshness, I seem to recall that you put a drop of it on a piece of glass or spread it out a little and let it sit overnight. If it is still gummy in the morning, it is past its prime. Also, I read somewhere that pure isopropyl alcohol works better than DNA so I just bought some 99.9% IA to try for my next batch.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

View Grayswandir's profile

Grayswandir

17 posts in 257 days


#8 posted 07-17-2021 03:27 PM

I appreciate the link for the flakes, that’s a fair price and way better then the crook selling it on Etsy like it’s gold bullion.

Thanks for throwing out some info on Acetone and shellac. I used acetone because I had it on hand, but I also did a little research before using it.

I wasn’t aware the Zinnser lasted that long. I wish they put a date on the can instead of a code. You have to call them up to find out how old the batch you bought is. Maybe I got an old batch, or maybe I just didn’t cut it enough? The only way to find out is to do a few tests. I think I should have cut it more because the chuck key handle I finished with shellac is like a hard candy shell, and is crystal clear.

Thanks for the little test info, I’ll try that out of curiosity. Generally, the isopropyl I’ve seen is usually 70/30 alcohol and water. I didn’t realize you could get it so pure?

Thank you.

View Lazyman's profile

Lazyman

8321 posts in 2678 days


#9 posted 07-17-2021 05:07 PM

Most “rubbing alcohol” is 70 to 90% because it is actually a better disinfectant in that range than in pure form. I’ve heard that you can find 99% IA cheap as liniment at horse tack stores but I could not find any in my area (not too many tack stores in the big city) so I bought some on Amazon. A little pricey but I just want to try it to compare to DNA.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

View Peteybadboy's profile

Peteybadboy

4173 posts in 3240 days


#10 posted 07-17-2021 07:49 PM

I will chime in on using flakes, mason jar, cheese cloth application using a squirt bottle to add to the cloth and keep moving the cloth, when it drags add more solution shellac from the squeeze bottle.

-- Petey

View LittleBlackDuck's profile

LittleBlackDuck

8269 posts in 2111 days


#11 posted 07-17-2021 11:54 PM


Oh yeah, Paul Sellers has a very good youtube on how to use shellac.

Link. About 30min long.

https://www.youtube.com/watch?v=UssYj-98oCg

- wildwoodbybrianjohns


I can beat that… A friend (master craftsman) made this, what turned out to be a lengthy video (1:28 hour). Contrary to Paul S., he doesn’t advocate brushes but talks about traditional rubber usage (including preparation) for French polishing.
If you aren’t after the traditional method, then don’t bother with this video... otherwise download it, grab a few beers and watch it on your TV with the feet up.

-- If your first cut is too short... Take the second cut from the longer end... LBD

View Grayswandir's profile

Grayswandir

17 posts in 257 days


#12 posted 07-18-2021 06:50 AM

The French way seems to give the best looking finish.

View wildwoodbybrianjohns's profile

wildwoodbybrianjohns

2849 posts in 838 days


#13 posted 07-18-2021 09:37 AM

A fellow L.J. called me out on the “M&Ms coated with shellac,” and he is right. M&Ms are NOT coated with shellac, they are coated with cornsryrup. However, most hard shiny candies, like jellybeans, are coated with shellac.

-- WWBBJ: It is better to be interesting and wrong, than boring and right.

View Robert's profile

Robert

4799 posts in 2771 days


#14 posted 07-18-2021 12:18 PM

This isn’t furniture, plain old Zinseer will do the trick. Memory serves, SealCoat is 2# cut, the regular waxed is 3# cut. Either way, you have to cut it 50/50 with DNA.

Personally I would just use shellac aerosol, unless this is an exercise in making shellac.

Wax applied with 0000 steel wool is a good way to finish shellac.

Shellac.net is a great outfit.

-- Everything is a prototype thats why its one of a kind!!

View Grayswandir's profile

Grayswandir

17 posts in 257 days


#15 posted 07-18-2021 03:51 PM

Thanks Robert, and yes, the waxed Zinnser is a 3lbs cut. Any particular type of wax, or anything will do?

Candy corn is apparently coated with shellac as well as jellybeans.

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