Shellac help

[Eric Pitts]

I'm trying out shellac for the first time. I used a 2 lb cut of dewaxed shellac. I was sloppy on my first coat and I got some dark spots where it ran from the inside of the wood to the outside. I let it dry, sanded it a little bit with some 400 grit paper, then put another coat on. I had hoped that the little sanding would help and then it would dissolve into the second coat, but it didn't. Is there a trick to getting rid of these spots? Do I have to sand it down to the wood again and re-do it, or can I do something to help dissolve it away?

I attached a picture to show what I'm talking about. (hopefully it worked)

Thanks,
Eric

[John Coloccia]

I think what you're seeing is where the shellac has discolored the end grain. I usually put down a 1lb cut of shellac over the entire piece before finishing. Sometimes I'll do two coats on end grain depending how it looks and feels to me. I usually just pad it on, though if I happen to already be spraying shellac for something else, I'll spray it on out of convenience.

I suspect you'll have to sand it back to the wood. I can't tell from the photo. Is that mahogany?

[robert raess]

is there physically anything there to the touch: a bump or such.?I notice where they appear is a the bottom of the hole.try taking a white cotton rag, and put a small amt. of alcohol[not enough to drip]and rub in a circle, and when it is gone swipe it on and off like an airplane.The nice thing about shellac is that it is quite reversible. Rob

[Eric Pitts]

I don't think it has discolored the end grain, there is a bump where it has built up. I'll try using some alcohol on a rag to fix it. That's what I suspected, but I ran out of alcohol so I figured I'd check here. I'll do anything to avoid more sanding. I've had to sand enough already. It is mahogany, and there is a ton of end grain.

Thanks guys

[Kent A Bathurst]

Sounds like nothing more going on that "drips". Where you can feel the bump - that is nothing more than a much, much heavier coat of shellac than you have on the field. If you revert to sanding them back, I personally would be using something more aggressive than 400g. Prolly in the 220 range. Getting rid of it also means taking out the surrounding finish, of course. I would probably re-apply with a combination of a padding cloth and a small artist's brush, being attentive to blend in with the surround. I would expect you can work it all back with DNA - not sure if that will save strokes or not - just need to be attentive to blending the repairs to the field.

Good luck. Whatever that piece is, it looks pretty cool. Hows about a bigger photo to let us see what you're making?

EDIT: Eric - BTW - " I've had to sand enough already". I cry out "Enough already!!" every time I am sanding. Then, of course, I just grimace and keep sanding. :D I remember reading somewhere, years ago, somebody said "If you absolutely cannot stand sanding, find another hobby."

[Prashun Patel]

Eric-
The alcohol should solve it. Remember, though, you don't have to sand the entire piece - just those little nibs. It looks relatively easily fixable.

[Scott Holmes]

I would suggest you scrape the drips off. Use a razor knife blade, it's stiff and works well as a scraper. I usually hold it between my fingers not in the blade handle/holder. Once the bulk of the drip has been removed a rag damp with denautured alcohol will blend the drips to the rest of the surface.

[John Coloccia]

Ja....if it's drips, scrape mit der razor blade. If you find it too grabby, and you may the first time you try, run the edge once along a piece of steel, and that will dull it enough that it won't grab anymore.

[Eric Pitts]

Well, I did some sanding, scraping and used some alcohol and it helped. Thanks for the help.

It is a cradle that I made mostly from recycled mahogany off some old couches and chairs. I would have liked to touch it up a little more, but the user decided he wanted to come out ten days early so I ran out of time. I really didn't anticipate how long it would take to sand all the grooves in the panels.

[glenn bradley]

That's a wonderful piece Eric. Scott and others took the words out of my mouth as to the recovery method. Prime Directive on shellac; use as thin a coat as possible. Shellac is not really a film building finish. It is sometimes used this way as a grain-filler but, I wouldn't want 6 coats of 2lb cut shellac on my table top if you get my drift ;-). Again, I really enjoy looking at that piece and would welcome more shots or a discussion of the techniques used.

[Kenneth Speed]

Shellac is a wonderful finish but it has some very distinct peculiarities. One of these peculiarities is that the solvent, denatured alcohol, dries very quickly which makes it very difficult to apply shellac with a brush and get a smooth coat. One ancient trick is to add a VERY small amount of turpentine to the thinned shellac. Start out with a couple teaspoons to about a quart and try a test piece. if it dries too fast add a little more turpentine and try again. Don't substitute lacquer thinner or mineral spirits, they won't work.

Shellac, unlike varnish dissolves the previous coat somewhat when its applied so the first coats need not be absolutely perfect.

Another characteristic of shellac is that it is soft compared to varnish and lacquer so it can be easily abraded and or polished to an even sheen.

Shellac isn't the most durable finish but can be used as a final coat when spills aren't an issue. I made a natural edge headboard from big leaf maple that I finished with shellac and then paste wax.

I'm somewhat surprised that some hand saw restorers are using shellac on the totes. I'd expect perspiration would attack the shellac, maybe they're adding a final varnish coat.

[Scott Holmes]

...
Another characteristic of shellac is that it is soft compared to varnish and lacquer so it can be easily abraded and or polished to an even sheen...
.

Actually de-waxed shellac is HARDER than most varnishes; the only varnishes harder than de-waxed shellac are the two part conversion varnishes. Shellac that still has the wax can be softer than varnish.


Another property of shellac is that when applied too thick it is prone to alligatoring. The perfect shellac finish is the thinnest possible coat that is flawless.

[Jeff Hamilton Jr.]

That's a wonderful piece Eric. . . Again, I really enjoy looking at that piece and would welcome more shots or a discussion of the techniques used.

What Glenn said . . . !

[glenn bradley]

Actually de-waxed shellac is HARDER than most varnishes; the only varnishes harder than de-waxed shellac are the two part conversion varnishes. Shellac that still has the wax can be softer than varnish.

Thanks (as always) to Scott for highlighting this common misconception. Shellac users seem to fall into two categories; really like and really don't like. :D I need a definite requirement to use a varnish and a gun to my head to use poly. I guess you could say I am in the "really like" camp on the shellac thing.

[Kenneth Speed]

Scott told me, "Actually de-waxed shellac is HARDER than most varnishes; the only varnishes harder than de-waxed shellac are the two part conversion varnishes." OK, if you say so but it doesn't feel that way when I'm sanding. I'd say nitrocellulose lacquer sanding sealer is the softest clear finish that I've used followed by shellac, I find a dried coat of varnish feels far harder to abrade than shellac.

Scott also said, "Another property of shellac is that when applied too thick it is prone to alligatoring. The perfect shellac finish is the thinnest possible coat that is flawless."

I agree, shellac is the perfect finish for multiple thin coats because it dries so quickly.

[Scott Holmes]

Kenneth,

Multiple thin coats can result in too much shellac... A french polish technique applied shellac is only a few mils thick when completed. Lacquer based sanding sealers have sterates in them them to make sanding easier.

Shellac is very hard and scratches very well; (ditto for lacquer) poly (a varnish) on the other hand is tough and doesn't scratch well (that's it's good quality for floors). Sanding is scratching when it can't scratch it as well; it seems to go slower, but it's not because it harder.

The harder the finish the higher the gloss that can be achieved. Shellac and lacquer can both out "mirror finish" varnish.

If you (or anyone else) want(s) to prove this to yourself; let varnish completely cure on a piece of glass along with shellac and or lacquer when you go to scrape them off you will see the varnish can be removed in one piece and the shellac and lacquer will be more brittle, they will chip etc., hence they are harder.

[sheldon pettit]

"" One ancient trick is to add a VERY small amount of turpentine to the thinned shellac""

Better to use N-propanol or N- butanol alcohols to retard the quick drying tendencies of lac.

[Eric Pitts]

I made a post in the projects section talking about the cradle.

http://www.sawmillcreek.org/showthread.php?185718-Cradle&p=1918466#post1918466