I have been reading about the various threads on shellac applications in the site and am interested in using it myself for a final finish as I am now using polyurethane. I see where you can “slop” it on and like the idea of how forgiving it is but am clueless on how to finish the final coat. Slopping it on doesn’t seem “in my mind” to work on the final coat. Someone mention varied use of sand paper down to 1000, then polish the last coat. How is this accomplished? If I didn’t do some variation of french polish what other methods do ya’ll utilize to finish out shellac. Once again in my mind, the addition of subsequent coats would eat each other, meaning the building up of coats would be hard to achieve. Obviously this isn’t true or you wouldn’t’t be using shellac as a finish but it just seems that way……. Any insight would be greatly appreciated. I just want to get all the facts before I dive into a new finish regime!
Also, if I bought zinsser 2 lb. cut finish, do ya’ll recommend cutting it further with alcohol?
Semper Fi
Replies
Jarhead,
Yes thin it out!
That's the trick to a good finish with shellac.. I use two gallons of alcohol to one gallon of zinssers 2# cut shellac.. I thin the second coat more and the third coat even more still.
I know it sounds crazy to sand your last coat but that's the process that you need to do to get a deep glossy finish.. start out with well worn 220 to remove any dust dirt or stuff that is less than perfectly flat..
Now here I scare people but it's the way I was taught.. use a little water to help show scratches. Mist a little on fully dried shellac and use a nice new squiggee to quickly wipe it off. Scratches will briefly show as tiny little lines of water.. sand off those tiny little lines and then go to the next grit, repeat.. go to 400 and sand the 220 scratches off. (should only take a few moments per bd.ft.) then sand the 400 scratches off with 1000 grit and sand the 1000 grit scratches off with 2000 grit and heck if you're going to french polish it keep going to 4000 grit.
That's the trick to a good finish with shellac.. I use two gallons of alcohol to one gallon of zinssers 2# cut shellac.. I thin the second coat more and the third coat even more still.
If I had a gollan of 2# shellac and I added two gallons of alcohol what would the end result be in cut? Obviously it wouldn't be 2#'s.......... This almost sounds like a wash coat? When I do the cutting I am going to do smaller amounts but use your 2-1 ratio, alcohol to shellac. How long will a batch mixed up (diluted)last? How long will the original 2# Zinsser shellac last?
Semper Fi
For canned shellac, you should not use it 6 months after it has been opened. When I open a can, I write the date on the lid with a Sharpie, just to make sure that I don't use it after the 6 month limit. This also applies if you are mixing it from flakes. It gets groady pretty quickly after it has been exposed to air, and I'd rather spend a few bucks for a new can of fresh finish just to have the piece of mind knowing that the project I've spent so much time building has a good finish.
Semper canus,
-Tom
TomG
Six months may be fine for you but it may be too soon or too long for others..
What happens is moisture sneaks into the opened can thru whatever way it can and starts to gum up the shellac.. Alcohol attracts moisture.. I know I bang the lid on fully and if it's mid summer with all the humidity we have here I am hard pressed to get a few months out of it.. If it's winter as dry as things are here I can count on as much as 9 months.. Those in the desert could probably get forever, whereas in New Orleans in the summer I suspect there could be issues 14 seconds after the lid is off. ;-)
Yes it's really a wash coat which for those of us who aren't gifted painters (And I am not!) is the secret to doing really fine finishes without a great deal of effort..
What you are doing is preventing runs, drips, dry edges, brush marks, and other such issues. The thin coats actaully melt each previous layer and work towards making the surface smooth.. The sanding between coats is just to remove the inevitable nibs and such that are raised when the finish is applied..
Alcohol evaporates so quickly that in less than 15 minutes the whole piece is dry so if you try to do a careful run avoiding neat paint job you will be fighting all of the issues I mentioned earlier, (Runs drips dry edges brush marks) when you thin it out you now get to enter the Indy 500 of painting..Slop it on and just try to quickly cover everything.. Think of it as putting 1/3 of the required "paint" on at a time..
Now here's the really wonderful part. If I'm lying to you, simply wash the first coat off with pure denatured alcohol and do it whatever way trips your trigger.. It will wash right off. Doesn't matter how many days/weeks/months/years/decades/etc.. you let it dry.
I've got mixed parts of a gallon here that I keep adding to and I'd guess the original is nearly 8 months old. But I just use the same can.. add shellac and alcohol as needed.. By the way if you ever forget and let a brush dry out, soak it in alcohol and it will eventually come clean.. Shellac always disolves in alcohol.. (kinda neat for those of us who get in a rush)
I don't know how long it lasts in the can. What happens is moisture gets in and kinda turns things waxy. A nice dry climate is easier to work with than the humid days we get here in the summer..
Once finished the shellac should last decades My piano is over 80 years old and it was starting to show distress. a few hours of washing with alcohol and it was baby butt clean and smooth.
Do not make the mistake of thinking more is better!
Too thick and the original finish will alligator. Too thin and it will wear out. Three thin wash coats and it should hold up untill you want to make it perfect again..
Shellac, like other film finishes, needs to be rubbed out to achieve its maximum potential. This starts with sanding smooth. You seldom need to start as coarse as 220 grit. I often start with 400 grit if I have done a good job of applying the finish material and have smoothed out major imperfections with 320 between about every few coats. I then work up to about 1200 grit. At that point I usually go directly to rottenstone, lubricated with paraffin oil, which will give a very nice high gloss finish. This isn't really different than I would do on varnish, though the sanding and polishing is much easier on shellac.
I don't see the need to use shellac of so light a cut as you would get with two quarts of DNA added to 1 quart of Seal Cut. (It works out to less than 0.59 lb. cut.) For padding on with a rag, I usually like a bit thinner cut--perhaps 1 lbs. or 1 1/2 lb. cut. It's certainly not a critical measurement. (To turn 2lb. cut Seal Coat into one pound cut, mix three parts of Seal Coat with two parts of alcohol.)
Two pound cut works pretty well with Taklon gold watercolor wash brushes. These brushes don't apply heavy coats and leave no brush strokes so you still don't need to worry about a few gaps or overlaps--the next application with take care of it.The key is always to move quickly without going back. If you notice either brush or pad showing any drag, STOP and let the shellac dry before continuing.
Jarhead,
Do a Google seach for french polish. It is not simply a way to "polish" the surface of a shellac film, but a laborious method that involves using abrasive (pummice) in the early stages to actually form a wood dust/shellac mixture as a filler. Like many people, I use padding techniques that come into play in the late steps of "real" french polishing to polish a shellac film that hs been built up by means other than the traditional, "true" french polish method. (I also do tradional french polish).
For a non-traditional method, finish sand the wood to 220-320 grit, apply shellac as has been described in the previous threads. Carefully scuff sand with 220 grit the first several coats to remove raised grain and finish nibs. Use 2# or thinner cuts as you like. With each succeeding coat, the light scuff sanding will take down more areas of the "mountains" and result in smaller and smaller shiny, unsanded "valleys" until it is possible to lightly sand and have the entire surface reach the appearance of perfectly flat ground glass.
When you get to that point, you are at or near the final coat. The final coat is then similarly abraded with 320, then 400 grit. I use a lubricant, starting at 400 grit, then 600, 800, 1200, then automotive rubbing compound (red) then automotive polishing compound (white) then swirl remover. (Don't bother with pumice or rottenstone, they are far inferior to automotive products as they vary greatly in their abrasive particle size.
You can stop at any of the high abrasive steps, depending on how the surface looks and experiment with a pad slightly damp with alcohol/shellac and a few drops of mineral oil for the final "french polish."
Edited 10/16/2006 12:53 pm ET by Rich14
I use a lubricant, starting at 400 grit, then 600, 800, 1200, then automotive rubbing compound (red) then automotive polishing compound (white) then swirl remover. (Don't bother with pumice or rottenstone, they are far inferior to automotive products as they vary greatly in their abrasive particle size.
Thanks for the reply, What type of lubrication do you use when sanding in the finer grits?
Semper Fi
Jarhead,
Mineral spirits (non-odor) or naphtha. I use a drop of dishwashing soap in a quart of water when rubbing out varnish. This would probably be ok for shellac aslo.
Rich
Edited 10/16/2006 3:08 pm ET by Rich14
Be a bit careful with soap here. Shellac does not react well to caustic or alkali chemicals. Ammonia is a good solvent for shellac, as an example. Paraffin oil works very well as a lubricant, and removes easily with naptha as a solvent.
Slopping it on doesn't work for first coats, either. Yes, the next coat can and will chenge the previous one(s) but using thin coats saves time and work. Let it dry when building coats or it will take longer than you want to harden.
This is a pretty good tutorial on French polishing. It's a very labor intensive process and the finish isn't very durable. I think it is suitable for fine musical instruments and special furniture, not for ordinary, everyday use.
http://www.milburnguitars.com/frenchpolish.html
I don't consider a finish finished until it has been leveled and polished. Most all spirit coatings will leave orange peel, to some degree, due to evaporation of the thinner. People hate poly because they leave it as it comes off the brush. Dust nibs and other surface irregularities are common with this product. You can get all kinds of final appearance with poly if you are willing to work it, from a mirror polish to what looks like oiled wood.
You need enough product on so that you will not sand through to bare wood. Some folks think that those mile deep finishes are achieved with a thick coating of product. It's really a matter of light reflection. A perfectly smooth surface won't break up the light like an irregular surface. When you look at your own reflection, you should be able to see individual hairs and edges that are not distorted.
Flattening and polishing can be done with many coating products. The product should be dry/cured. I start with 220 stearated or Norton 3X. I'm just looking to take off the dust nibs and other goobers. They show right up with one pass. I switch to 0000 steel wool which blends in any irregularities. The Liberon wool is worth finding. Use it plain for low gloss, add a drop of wool lube for a more polished look. After the steel wool, I use 3M Finesse II. So far it is the best polish I've found and easy to use. You can apply by hand or use a low speed buffer. I have good results using terrycloth bonnets or towels. Always work with the grain. Your finishes will take a quantum leap once you learn to "finish" them.
Beat it to fit / Paint it to match
Appreciate the tips and the web sites, I am going to give it a crack when I get a chance. I hope it works out like ya'll say it will. Finishing always seems daunting when you first start a new way or form.
Semper Fi
I just looked at the DVD from Taunton by Frank Klaus on finishing. In it he spends a long time showing french polishing. It is definitely worth seeing him do it to appreciate the pluses and minuses. He does it with shellac and some polymerized tung oil on a padding, But he he barely wets the pad and works it around. He gets a magnificent finish, but does say that it is not appropriate for a surface that will get wear or moisture.
DVD from Taunton by Frank Klaus on finishing
Thanks..... I'll look it up and see about getting it.
Semper Fi
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