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Shellac dry time

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Forum topic by MalcolmLaurel posted 03-29-2016 10:24 PM 451 views 0 times favorited 10 replies Add to Favorites Watch
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MalcolmLaurel

269 posts in 1088 days


03-29-2016 10:24 PM

Topic tags/keywords: shellac

For years I’ve used shellac as my “go to” finish for nearly everything. I had a little trouble today, though.

I had several coats of dewaxed shellac (Zinser Seal Coat) on two table tops which I plan to topcoat with lacquer for more protection. The last coats of shellac went on the night before last, and last night they seemed quite dry, so I flipped the tables over onto fabric covered surfaces so I could shellac the legs (several coats of regular shellac). Today, I flipped them back over again, and found the texture of the fabric had imprinted into the finish. Some light sanding and a first additional coat of thinned shellac again just now, hopefully it’ll level out again. But what went wrong? I guess “dry to the touch” isn’t enough for sustained pressure? It’s a new can from the hardware store (I learned the hard way about old shellac some years ago). I’m working in a heated garage, but at the end of the evening I turned off the heat so it got down to around 40° overnight. I did figure on a few extra days dry time before applying the lacquer, maybe I should bring them into the house for that time.

-- Malcolm Laurel - http://MalcolmLaurel.com


10 replies so far

View conifur's profile

conifur

955 posts in 616 days


#1 posted 03-29-2016 10:33 PM

First Shellac is an evaporation finish so temp does not effect as much as a oil/curing finish.
2nd I hate canned Shellac, I started out using Zinser but there is no date on the cans, just a batch code, so who knows how long it sat on the shelf, and after about a year it does not dry well. I mix my own now.
3rd, what kinda fabric? If synthetic might have interacted with the Alcohol.

-- Knowledge and experience equals Wisdom, Michael Frankowski

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SteveMI

954 posts in 2759 days


#2 posted 03-29-2016 10:34 PM

I have nothing to add, but am waiting for the advise you get.
Steve.

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MalcolmLaurel

269 posts in 1088 days


#3 posted 03-29-2016 10:39 PM

I’d like to start mixing my own but I haven’t done it yet. Still the hardware store I get it from has a pretty good turnover, I think; I haven’t had a bad can yet. The one time I did have a problem was an old can I had sitting around, who knows how long (I didn’t know any better) and it was still tacky months later. This time, it hardened to the touch just as I’d expect, so I don’t think it was bad. As for the fabric, one was a clean cotton shop rag, the other was an old u-haul quilted movers blanket, fabric type unknown.

-- Malcolm Laurel - http://MalcolmLaurel.com

View gfadvm's profile

gfadvm

14940 posts in 2155 days


#4 posted 03-29-2016 11:56 PM

Dry to the touch and fully “cured” are not the same as you learned. I have had the same issues only when I applied several coats back to back. I have learned that shellac is not designed to “build” a thick finish.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

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conifur

955 posts in 616 days


#5 posted 03-30-2016 12:08 AM



Dry to the touch and fully “cured” are not the same as you learned. I have had the same issues only when I applied several coats back to back. I have learned that shellac is not designed to “build” a thick finish.

- gfadvm


I tend to differ, Shellac coats melt into each other by the fresh coat activates the dry coat, I dont use Lacquer but I think it does the same, unlike oil and water based Polys layer on top of each other. That is why with them you can get ”’rub thru”’ between coats when sanding.

-- Knowledge and experience equals Wisdom, Michael Frankowski

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gfadvm

14940 posts in 2155 days


#6 posted 03-30-2016 12:13 AM

Conifer, The difference is applying subsequent coats over dry coats as opposed to recoating as soon as it is dry to the touch. The latter is when I have problems.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

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sawdust703

270 posts in 885 days


#7 posted 03-30-2016 12:27 AM

Shellac can be tricky to deal with. Up until a year ago, I’d never used it. Polyurethane was my go to finish. It took me what seemed like forever to learn to use shellac. I finally started using my air sprayer, & found I got much better coverage, & a more level finish with the shellac, therefore making the lacquer look even better. I hang my projects, if possible, after the shellac dries enough to handle, & then leave them alone overnight to allow the shellac to cure out.

-- Sawdust703

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MalcolmLaurel

269 posts in 1088 days


#8 posted 03-30-2016 12:35 AM

Well, a light sanding followed by one thinned coat and one not thinned and it looks good again; I’ll give it a few days before applying the lacquer. On lamps and table legs I use only shellac; I only use the lacquer on the table tops to protect the shellac from a spilled drink. Polyurethane has its place and I do use it occasionally, but I don’t like working with it and I don’t care for the “plasticy” (is that a word?) look.

Typically I apply 2-4 brushed coats of shellac in an evening and then let it dry overnight before adding a few more coats.

-- Malcolm Laurel - http://MalcolmLaurel.com

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conifur

955 posts in 616 days


#9 posted 03-30-2016 12:43 AM



Conifer, The difference is applying subsequent coats over dry coats as opposed to recoating as soon as it is dry to the touch. The latter is when I have problems.

- gfadvm


Well that is your problem the first 1-2 coats dry fast, then prudence is needed till the next coat.

-- Knowledge and experience equals Wisdom, Michael Frankowski

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gfadvm

14940 posts in 2155 days


#10 posted 03-30-2016 02:22 AM

Exactly!

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

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