Couple of Shellac questions

[Mike Willeson]

First, the safety question...just got my first qt. of shellac and like what it does to the wood. Does shellac have the same safety concerns with rags as Antique Oil (and maybe BLO) - if you leave rags laying around with shellac they could start on fire? (I'm not planning to do that, just want to understand the hazard level)


On to the fun stuff....do you gain by having multiple coats of shellac or is it just overkill? I am wondering as it pertains to filling pores and wet sanding. On the first piece I tried I put on shellac while on the lathe, rubbed it in while spinning. Later, I did the same with another coat and then called it a night. The next evening I took some shellac on a rag and some 320 wet sanding paper and ran the lathe with the rag on top of the piece and the sand paper underneath the piece. Sanded it a bit and then dried it while spinning. The next day the surface was really great.

So I guess my question is....I wet sanded on the 3rd coat. Would it have been just as nice wet sanding on the first and only coat or did the extra layers of shellac help?

How's that for a run-on question....?

Any thoughts on shellac usage for turnings would be much appreciated.

Thanks,
Mike

[Steve Vaughan]

Mike, I looked on my can of shellac and it didn't say anything about it being combustible. Shellac dries from the evaporation of the alcohol(?) leaving the actual shellac on the surface. Oils (I think?) dry from a chemical reaction with the air and that's what makes those products combustible. Someone else will have to give an official explanation, but I think all that's correct.

HOWEVER, when dealing with any finishes - oil or shellacs/laquers/etc. - I would always assume the combustible factor as being possible and treat rags, etc. with that in mind. I've had my time of nearly causing a fire with a rag soaked with BLO and found just before the fire. I ALWAYS take rags and open them up and lay them on my concrete floor, or lay them across something where they can dry out completely and easily.

My experience with shellac as a finish is limited, but I've used it as a pore filler and to level out the surface for open-grain woods - it's great at that because it builds up fast. I'd put a coat down, let it dry completely, sand it back, and go with another coat and maybe a third.

[John Keeton]

Mike, I use shellac a lot. The content of shellac is simply shellac flakes and denatured alcohol. Zinsser's Seal Coat, which is de-waxed shellac, is a 2 lb cut, meaning that 2 lb. of shellac is dissolved in a gallon of DNA. It is highly combustible in that form. However, the alcohol flashes off quickly and when that rag is dry - pretty quickly if left unfolded, it is no more combustible than the rag itself. Shellac does not harden by polymerization, the process by which heat is generated, so it is not subject to spontaneous combustion as are oil-laden rags.

Multiple coats of shellac make a great finish if done properly. I normally do not wet sand until after the third or fourth coat.

You can also tint shellac with dyes for a very nice effect if done right.

[Michelle Rich]

I have used shellac for eons. I use it as a final finish, and as a sanding sealer. To get a super finish, at around 320-400, put on shellac & let dry. The sand with 320. repeat at 400 -600 etc. (no need for wet) The sandpaper will fill with shellac, & you must change it out. The shellac is melting and going into the open pores and onto your paper. At 600 you have a great base for final finishing. At this point I use EEcream and then wax (I'm lazy & that is myfinal finish) Your pieces will shine & FEEL SUPER. Will feel like no finish at all

[Mike Willeson]

Thanks for the info so far...I appreciate it. One more question to add....I looked all over the can (the print is getting smaller all the time) and can't find anything about stirring.

Does shellac separate? Is stirring required / recommended?

[Russell Neyman]

The answer is "probably no" but what can it hurt to give it a stir (as long as you don't create bubbles in the resin)?

[John Keeton]

The de-waxed shellac does not need to be stirred. I don't use anything but de-waxed, however, in the event you use waxed shellac it should be gently stirred.