Shellac bungle

[Sam Puhalovich]

I've bungled my first attempt at using shellac for a finish. Zinsser Bulls Eye Shellac ... clear. Dry-to-touch in 30 minutes ... recoat in 1 hour. I stirred well > blew-off the surfaces > using my HVLP > I applied the first coat. Waited 2 1/2 hours > lightly wiped surfaces with 320. Surfaces were silky smooth. I stirred again > blew-off the surfaces > applied the 2nd coat. It looked-like-a-mirror. Waited one hour > surfaces looked-and-felt 'rough'. Let-it 'sit' over-night ... 24 hours later ... no difference ... it was still 'tacky' in some spots. My guesses are that the shellac 'set-up' somewhat in-between-coats, then was applied too thickly. However; my main dilemma / question is ... how do I recover? Shellac.jpg

[glenn bradley]

Shellac dries very quickly. In my experience if it remains gummy you have too thick an application or if it is too old. Again, in my experience, you are in one of two worlds; the shellac will cure in a few hours or it will not. If it will not, you would have to remove the excess.

To remove the shellac I soak rags or paper towels in denatured alcohol and scrub the shellac off. Change rags or towels frequently since you are trying to remove the material and cast it into the trash. Once you get down to a near-clean surface, let it dry for an hour or so, sand smooth and reapply a thinner coat.

I pad shellac. Spraying seems like it would be apt to apply way more finish than one wants. Maybe some folks familiar with spraying shellac can chime in.

[Mel Fulks]

Before getting into fixing ,I would watch and wait a whole week, might just dry ok. I’ve heard that’s a good product, but I prefer to mix my own with new shellac flakes and denatured alcohol that has a tight top, seen a bunch on store shelves with non- tight tops.
Wishing You Good Luck !
Mel

[Scott Winners]

I agree with Mel, give it a week to fully cure before you go crazy trying to remove it. With part of that time, look up how to read the date code on the Zinsser cans of premixed shellac. You will get lots of hits with a basic internet search on any search engine. Pretty thorough article on either pop woodworking or fine woodworking, I don't remember which.

I do want to switch to making my own finish from dry flakes and denatured alcohol, but I really need a chemical cabinet first as I have finish products scattered hither and yon within the shop already. I did use Zinnser premixed shellac on my earthquake proof shelves currently on page one in the project section here, and I had a thread here in the finishing section summer 2022 about my woes with Zinsser shellac that was about 6 years old...it doesn't last six years in the jar before application.

[Sam Puhalovich]

From The Purple Painted Lady:
"Shellac is produced from natural materials. Which means – shellac is also perishable. Perishable- in the sense it has a shelf life, an expiration date…in other words…it is no longer good after a certain date – so don’t use it. Sort of like spoiled milk…eew!Cans of shellac are often marked with their date of manufacture. Now here is the interesting thing that most do not realize- Shellac typically expires 6 to 9 months after the date of manufacturer. So when buying shellac, if you go to a store and you find some in the way back of the shelf covered with dust…you may not want to purchase it.
When Shellac passes its shelf life date it begins to undergo a chemical change and it will gradually take longer to dry, and the dried film is softer and more prone to scratches and water damage and poor performance. Meaning- it is not ideal to use."

My can = S4422B = 2014 April 22. It's been 'stored in my basement AC'd workshop where the temp is a steady 76* and RH ~60. When I opened-it, the top 'popped' and hit-me in the nose.

Glenn, Mel, Scott ... thank you. I think that I bought that can in 2015. Before I got started, I did a 'search' ... here ... and read a lot of supportive posts about spraying shellac. Nobody mentioned shelf life. My first thought was as Glenn mentioned ... scrub-it-off with DNA and start all-over. Mel: situation is: it's so rough ... I'm guessing that it's not going to smooth-out on its own. By-the-time I get thru sanding I'll be back close to bare wood. Padding and brushing did not appeal to me as the 'box' is 20 x 22 x 42 with 'battens' all-around. Scott: for my next try I'll find someplace to buy dry flakes and mix my-own. Again; thank you for the 'lessons' guys.

DSC_2090.jpg

[John TenEyck]

Zinnser shellac lasts 2 or 3 years in an unopened can. 2014 though is far beyond its shelf life. Now you know.
Shellac is about the easiest finish to spray, but it's best to cut it to 2 lbs or less so you don'tpit it on too thick. Then spray two or three barely wet coats, maybe even four if the wood is really thirsty.
There is no need to mix your own. Just don't use old product. Also, you can make any color you want by adding TransTint dye to Sealcoat shellac. Sealcoat is dewaxed so you can apply any finish over it.
John

[Brian Tymchak]

I just recently learned that shellac flakes have a relatively short shelf life too, about 3 years plus or minus. That was a shock to me. I figured flakes would be good for a long time.

[Mel Fulks]

We were just determined to give you a good shellacking.

[bill godber]

denatured alcohol will dissolve shellac,watch out for the fumes.

[Mel Fulks]

I just recently learned that shellac flakes have a relatively short shelf life too, about 3 years plus or minus. That was a shock to me. I figured flakes would be good for a long time.

That does seem strange, don’t think I’ve heard that before. Years ago I did read the book: Shellac: It’s Origins and Applications.
Might be something about a ‘use it or lose it ‘ thing in there.
One thing I do remember reading ….somewhere , is that some finishers will only use the drinkable alcohol to dissolve the flakes.

[Sam Puhalovich]

Thanks, guys ... I appreciate the shellacking of helpful info. I was surprised to find, yesterday AM, that the 2nd coat seemed to have dried hard. In the PM, I tried a few spots with a scraper and it seemed quite-hard. I decided to let-it-sit another day ... and today I'll make an attempt at sanding it smooth. If that doesn't go well: I'll take-it outside and strip with the DNA. After some-more reading, I found that the Zinnser-in-a-can is a 3 pound cut. I'll be sure to check the date on the next can and will be thinning-back to something just-less then a 2 pound cut.

[Rob Young]

I just recently learned that shellac flakes have a relatively short shelf life too, about 3 years plus or minus. That was a shock to me. I figured flakes would be good for a long time.

I have some flakes stored for maybe 5 years now. No issues but I haven't sampled from every bag. I just use up a bag and move to the next. Most recently maybe a month ago when I cracked open a new bag of "super blonde" flakes. The majority of my stash is "super blonde" and "garnet" flakes from Wellermart.

However, I double bag them and toss in a few desiccant packs for good measure in the outer bag. The shellac came in very heavy and heat-sealed bags and I use freezer zip-lock type bags as the second bag. Squeeze out the air for good measure.

I vaguely recall a discussion some time back about using vacuum sealers for this sort of storage. Not tried it and I don't recall if there was any long-term report on effectiveness.

[Prashun Patel]

I suspect your issue is that you sprayed on a thick coat - not that it is too old. Shellac dries very fast and a thick coat can trap solvent - solvent that will eventually make its way out. This manifests in an initially softer finish that doesn't dry as hard or powdery-when-sanded as you expect, some shrinking of the surface as the solvent escapes and creates voids, or worst (if it's heated) a pop where the alcohol forces to the surface too quickly.

All 3 have happened to me. The trick is to spray on very thin coats.

Last, consider using Zinnser Sealcoat instead of Bullseye. It's dewaxed, and about a 1.5# cut. So, it's more forgiving and versatile as a finish or sealer. The color is about half way between the blonde and the amber bullseye products.

[Sam Puhalovich]

Thank you Prashun ... some more golden advice nuggets to use in the future. The learning curve goes-on ... though I got-off to A 'shaky' start: I'll definitely be using shellac in-the-future. It's looking-like Mel Fulks had the right 'fix' ... wait-it-out and let-it-dry. Yesterday at 8 AM ... being anxious to get-it-done and not with a 'doubtable' finish ... I tried sanding with sterate 220. It 'corned' pretty quickly without any significant removal ... switched to sterate 150 without gaining much difference. Decided that I'd have to use Glen Bradley's approach and started looking for a 5 gallon supply of DNA. I dreaded the thought of doing that stripping operation. Then I remembered Mel's advice. The forecast for-the-day was 92* with 45 RH ... I took the 'stuff' outside to sit under the deck where it would be in shade up-to 7 PM. This morning it's looking-like I'll be sanding late this PM to smooth-out for the next THINNED coat(s).

[glenn bradley]

Yay! Learning to salvage our mistakes is a critical part of our success in the home shop. Glad it worked out.