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Can anything be put over shellac?

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Forum topic by natenaaron posted 07-30-2013 05:21 AM 1333 views 0 times favorited 30 replies Add to Favorites Watch
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natenaaron

370 posts in 463 days


07-30-2013 05:21 AM

So, I was not able to find Seal Coat anywhere in the next big town over. The tru-value here cannot order it, neither can the lumber store, so based on my previous snafu Poly is out. I know it will absorb blotchy.. Is there anything I can put over Shellac as a protective coat? Will an automotive clearcoat adhere to the shellac? I really want to get this project done. I go back to work Wednesday and would feel bad if this was another summer project left undone.


30 replies so far

View TCCcabinetmaker's profile

TCCcabinetmaker

925 posts in 1020 days


#1 posted 07-30-2013 05:34 AM

I have seen lacquer work, but it was a professional grade of lacquer. You might try…. car wax.

-- The mark of a good carpenter is not how few mistakes he makes, but rather how well he fixes them.

View shampeon's profile

shampeon

1377 posts in 849 days


#2 posted 07-30-2013 05:42 AM

Almost everything can go over shellac. Do a test panel and try it.

-- ian | "You can't stop what's coming. It ain't all waiting on you. That's vanity."

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TCCcabinetmaker

925 posts in 1020 days


#3 posted 07-30-2013 05:45 AM

eh, it’s usually best to stick to one type of finish to be honest, mixing certain chemicals can be risky. But like he said, make a test piece.

-- The mark of a good carpenter is not how few mistakes he makes, but rather how well he fixes them.

View tefinn's profile

tefinn

1211 posts in 1102 days


#4 posted 07-30-2013 05:59 AM

I use Deft and Minwax lacquer over shellac all the time. I also have used poly. It’s not recommended but it will work. Danish oil over 1/2 lb cut shellac is another that I use then top coat with poly or lacquer.

-- Tom Finnigan - Measures? We don't need no stinking measures! - Hmm, maybe thats why my project pieces don't fit.

View Rick M.'s profile

Rick M.

4022 posts in 1046 days


#5 posted 07-30-2013 06:56 AM

I don’t know what you are building but shellac is a finish coat and will provide protection. Unless it’s a dining table or maybe an end table, I’d just stick with shellac.

-- |Statistics show that 100% of people bitten by a snake were close to it.|

View Fred Hargis's profile

Fred Hargis

1817 posts in 1159 days


#6 posted 07-30-2013 10:58 AM

How about a non-poly varnish? It’s the polyurethane resins in those formulas that cause the adhesion problems, switching to a non-poly formula solves all that. You don’t even really need to scuff sand between coats with them unless it’s to smooth out the nibs. Try Sherwin Williams Fast Dry Oil Varnish (alkyd resin/linseed oil formula) or Pratt And Lambert 38 (alkyd resin/soya oil). I do agree with Rick that shellac is a good finish on it’s own; it’s underrated by most folks. But for things that have wear, a good varnish works well.

-- Our village hasn't lost it's idiot, he was elected to congress.

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natenaaron

370 posts in 463 days


#7 posted 07-30-2013 05:26 PM

This is a coffee table so it will see some heavy use and propping up of feet. Shellac scratches too easy and was wanting something as a top protective layer. I thought anything would go on top of shellac but when my finish blew off the top, literally, I am now pretty gun shy.

I will look for varnish

View crank49's profile

crank49

3443 posts in 1636 days


#8 posted 07-30-2013 05:32 PM

+1 on anything can go over shellac.

Shellac is the original seal coat.

You can even cover Vaseline stains with shellac and then paint over it like it was never there.

-- Michael :-{| “If you tell a big enough lie and tell it frequently enough, it will be believed.” ― A H

View Hammerthumb's profile

Hammerthumb

1327 posts in 641 days


#9 posted 07-30-2013 05:41 PM

I would assume it was regular shellac and not de-waxed that you had problems with, as almost anything can go over de-waxed shellac. I have also heard of woodworkers letting the waxed shellac sit undisturbed for a while and you will notice the wax settling to the bottom. The shellac can then be removed from the can leaving the wax at the bottom. You could then use this as the final coat of shellac prior to other finishes. There was another thread going round on LJs where someone asked if there had been any personal observations where poly did not adhere to a regular shellac surface. You might want to chime in on that thread to save the guy some problems. I have no experience with waxed shellac and non-poly varnish as stated by Fred Hargis, but do not see why this would not work. Try a test piece. Good luck!

-- Paul, Las Vegas

View ChuckV's profile

ChuckV

2427 posts in 2193 days


#10 posted 07-30-2013 05:47 PM

I think it is more correct that anything can go over dewaxed shellac. Seal Coat is the dewaxed stuff, which you were not able to find.

From the highly recommended book Understanding Wood Finishes by Bob Flexner:
The wax slightly reduces the transparency of the shellac on the wood. It also makes the shellac less water resistant, and it prevents good bonding when reactive and coalescing finishes (varnish, two-part finishes, and water base) are applied over shellac.

EDIT:
Paul beat me to this response. The method of dewaxing the shellac yourself that Paul refers to is also covered in Flexner’s book.

-- “That it will never come again / Is what makes life so sweet. ” ― Emily Dickinson

View Clint Searl's profile

Clint Searl

1465 posts in 1027 days


#11 posted 07-30-2013 05:55 PM

Your experience is yet another recurring example of the fallacy of starting every finishing project with shellac.

Do it right: strip it and finish with only waterborne poly floor finish. If it’s tough enough to walk on, it’s tough enough to put a coffee cup on.

-- Clint Searl....Ya can no more do what ya don't know how than ya can git back from where ya ain't been

View Fred Hargis's profile

Fred Hargis

1817 posts in 1159 days


#12 posted 07-30-2013 06:07 PM

Quote: I will look for varnish.

Nate, the polyurethane you used was/is varnish. Thanks to Norm, stupid finishing company marketing, and probably several other things many folks think of “poly” as a different finish than varnish. Varnish is a finish made by cooking a resin (normally one of polyurethane, urethane, alkyd, phenolic) with a drying oil (normally linseed oil, but can also be tung oil or soya oil, maybe some lesser known ones) and the result is varnish. So what most folks call “poly” is (maybe) more correctly varnish, just made with polyurethane resins. Some of the waterborne finishes are now being called “poly” as well, and they are actually just an acrylic waterborne finish like most others, with a dollop of polyurethane resins added. Whether shellac is dewaxed or not is only important if you plan to top coat with a poly finish…otherwise, pretty much all the other stuff will stick to it.

-- Our village hasn't lost it's idiot, he was elected to congress.

View natenaaron's profile

natenaaron

370 posts in 463 days


#13 posted 07-30-2013 06:19 PM

I prepped and sprayed the metal portions of the table with enamel clear coat. Will that work for the table top.

View Fred Hargis's profile

Fred Hargis

1817 posts in 1159 days


#14 posted 07-31-2013 11:32 AM

When you say “will it work”, without knowing a little more about exactly which one it is, I’d say it will stick (back to what I said about the urethane resins earlier). Whether it would look good and meet your criteria is your call.

-- Our village hasn't lost it's idiot, he was elected to congress.

View RogerM's profile

RogerM

451 posts in 1065 days


#15 posted 07-31-2013 02:03 PM

Seal Coat is nothing more than dewaxed shellac diluted with alcohol. Try mixing your own Seal Coat if you would still like to go that route. I have used it for a number of years with ecellent results. You can easily order Seal Coat from Rockler for around $15.50 a quart.

You do not indicate where you are located so not sure about your local suppliers. Both Loews and Home Depot stock Seal Coat.

-- Roger M, Aiken, SC

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