Finishing with Shellac - question

[Dennis Peacock]

OK...I have only been using shellac for a very short time now. I primarily have been using lacquer for most of my finishes. I have been applying the shellac in a 1.5 pound cut with my HVLP gun. From paying attention to the spray pattern and atomization at the tip, it looks OK. What I am getting is a bumpy finish after spraying. Am I not putting it on heavy enough for a complete wet coat? I also realized that if I put my hand on the shellac surface after 24 hours of drying that I can leave a pretty nice personal "print" in the finish. How long does it take this stuff to "really" dry? I am using Zinsser Clear Shellac and it is new out of the store and is a long way away from even being close to the expiration date...about 1 year away from what is on the can.

I even reduced it to a 1 pound cut and tried spraying with that and I get the same results. What gives? At least with lacquer, I get a smooth flat surface after spraying.

Advice, pointers and what am I doing wrong?

[Jim Becker]

Dennis, I haven't sprayed shellac yet, but one of the best guys I know who "knows" shellac is Steve Mickley, an excellent furniture maker in Ohio who also helps with the finishing forum at another site. He has some useful information on shellac on the personal side of his web site, although not on spraying and is good with answering email from "us woodworkers". Nice fellow. The Dresdner Spray Basics video I have features shellac being sprayed. (Taunton Press)

[Jason Roehl]

Dennis, I would hazard a guess that the problem is not the slowness of cure of your shellac--if that were the case, it would level out much more than what you're indicating. My thinking is that your shellac is actually starting to cure too quickly due to the atomization from the HVLP. More total surface area in the mist droplets = quicker evaporation of the alcohol solvent. I think that possibly your fingerprint could be either transfer or the fact that the finish didn't fully "grab" due to partial cure before impact with the surface.

I'll have to give HVLP'ing shellac a shot sometime--all I've done spray-wise with it is 2400s.f. of floor with an airless sprayer. That was SealCoat, at the 2lb. cut it comes in from the can. I've heard of "alcoholic hazes" before, but sheesh....

My recommendation would be to cut it less (larger droplets) and your HVLP should still be able to handle it, and also cut back on your atomizing air a little, and also go for a little thicker coat.

Or, you could always french polish...

[Jim Becker]

My thinking is that your shellac is actually starting to cure too quickly due to the atomization from the HVLP.

Hmm...Dennis, are you using a Turbine system? That also "could" cause what Jason refers to given the "hotter" air these provide to the gun.

[David Rose]

Dennis, I've padded shellac a lot and brushed it a little. So far I've only used home brew. All the cuts I've used from 1/2 to 3# will dry enough to touch in under an hour usually. You *can* leave an imprint sometimes in the finish for a few minutes with pressure, but the piece is still carefully handlable. But after a few thin coats of padded shellac waiting an hour is enough to start padding again. It isn't ready to rub out at that point.

You've got heat in your shop now, don't you? I can't remember. I've had this result (drying in an hour) from 50 degrees on up. When I've finished right in front of the heater blower, it dried too fast to use. Blowing air (the sprayer) might have something to do with it like Jason said, but the "gun guys" will have to help you with that one.

Shellac is really a neat finish. Hang in there until it works for you.

David

[Tom Scott]

Hmmm. I've only padded shellac, so I can't be too much help on the spraying aspects, but one of the great things about shellac is how fast it dries. It's usually dry to the touch within about 5 minutes.
I went to the shellac seminar at CurlyWoods the other night, and the Jim Kull says he most often sprays it with a conversion sprayer, cautioning that a turbine HVLP creates too much heat and it actually cures in the air.

Tom

[Dave Avery]

Dennis,

I, too have never sprayed shellac, but I think the other guys are right. The heat (or being too far away from the surface being sprayed) is causing the rough surface. As to not curing, the other guys are right, shellac usually dries to the touch in a few minutes. I'll hazard a guess that the HVLP is applying too much finish, causing the drying woes, if that makes any sense. Good luck figgering it out. Dave.

[Dennis Peacock]

Dennis, I would hazard a guess that the problem is not the slowness of cure of your shellac--if that were the case, it would level out much more than what you're indicating.

My recommendation would be to cut it less (larger droplets) and your HVLP should still be able to handle it, and also cut back on your atomizing air a little, and also go for a little thicker coat.

Or, you could always french polish...

Jason, Lots of good info and great thinking there.!!! I am using a HVLP conversion gun attached to my normal compressor. Just a little bit ago I tried cutting back on the air at the nozzle to narrow the spray pattern and that seemed to help some. I also tried slowing my movement some and that also seemed to help some. I see what you are saying and I guess I am going too fast and too much air at the nozzle to try to get an even spray pattern.

Jim,

I don't have a true turbine HVLP setup....only a conversion gun being ran from my compressor. I like spraying shellac as it is not as bad on my shop heat as spraying lacquer. Lots less explosive and I can breath in the shop after about 15 minutes of airing out the shop.

[Dennis Peacock]

Dave,

I haven't thought about applying too much at one time, though I do have the gun set for a fairly thin application. This is only my second time spraying shellac and I am still learning. Shoot, after a while, I should be able to answer shellac questions like the real shellac dudes.

Tom,

I REALLY wanted to go to the Curly Woods Shellac Seminar, but couldn't arrange time off at work to make the trip to Texas for a Thursday night class. Maybe I can make the next one if they have another shellac class.

[Tom Scott]

Dennis,
Mike says his next seminar will probably with Jim again, but this time on dyes...no date, but maybe around March-ish.

Tom

[Perry Schmidt]

I did get to attend Jim's seminar thanks to Mike - VERY good. (Thanks for setting this up Mike!)

Can't say I've ever used shellac or sprayed it but the short answer from what I learned at the seminar is it drys very fast. If it's taking that long to dry, the shellac is bad. Jim basically said never buy shellac in a pre-mixed can from anywhere. They put retardants in it to preserve it which causes problems. Many times the stuff on the shelf is bad. He said always mix your own. And mix what you need. After it's mixed it will go bad in a matter of weeks.

But according to him it drys fast - very fast. Under an hour. (Most of the time in 20 minutes or so, but after 24 hours if it's not dry I would think you have bad shellac.)

BUT also from Jim, it's easy to remove - just use alcohol and 'wipe' it off...then you can put new stuff on. I'm guessing it will take a little bit more than wiping, but that was one of his big pluses for shellac. If you don't like what you put on - even if dyed, you can rub it off easily w/ alcohol and try again.

From what he described it really sounds like you just have a can that went bad. Try to mix your own.

Hope that helps.

Perry

[Alan Turner]

I have been spraying shellac for about one year now, and have not had the problems you describe. I use an Asturo gravity gun, 1.5MM tip, HVLP, and keep the pressure as low as possible. I do not use a pressure guage, but just back off the pressure a bit too much, and then give it a bit more till it just atomizes.
I use only the home brew, dewaxed. The flakes last forever. I mix it in a quart jar, at 2# using a free digital postage scale to the 1/10th oz., and once dissolved it seems to keep for several months without problem, if I am not doing to much finishing. I dut it to 1.5# for spraying.
Sometime I have a bit of orange peel, and can't explain it (poss temp?), but when that happens, I put a bit of retarder in the cup, and that seems to solve it. I do 4-5 coats a day, without problems, and could not leave a hand print in it after an hour. Rubbing out -- leave it a few days to thoroughly cure. A short week should be fine.
One of the things I like about spraying is that if I want to french polish, one uses all of the build up from the gun, and the polishing takes only a very short time. Most of the time spent french polishing is building up the film thickness.
Alan

[Wendell Wilkerson]

Jim basically said never buy shellac in a pre-mixed can from anywhere.

Perry

Actually, Michael Dresdner is recommending the use of Zinsser SealCoat as a replacement for mixing our own shellac flakes. Here's a direct quote from Dresdner's web site:

"Want an easier way? Zinsser now sells pre-mixed dewaxed shellac in a 2 lb cut, the ideal for most finishing application, in a format that flows better and has a far longer shelf life (3 years minimum) than what you mix yourself. It is called "Bulls Eye SealCoat." Now that this has come out, I may never mix shellac flakes again."

Link to full article on Dresdner's web site: <a href = "http://www.michaeldresdner.com/dres5.shtml"> Mixing Shellac from Flakes </a>

I think SealCoat is different than the Clear Shellac product that Dennis is using. SealCoat is dewaxed blond shellac so if you're trying add a little color with orange or garnet shellac, you'll still have to mix your own. Though it might be easier just to add tint to the SealCoat. Also, Zinsser is coming out with a french polish product that has gotten rave reviews from everyone that has tried the samples.

Wendell (shellac novice but learning)