shellac spray gun selection

[kooshball]

A while back I posted some questions about slowing the evaporation rate of denatured alcohol so that I could brush the top to my dresser. I will be experimenting with some glycol ether that should do the trick but in the event that it doesn't work as planned I would also like to explore the option of spraying the shellac.

Based on your experience; what gun / tip combos are ideal for this job and what cut of shellac is typically used? Don't worry I have plenty of scrap to practice on...

Thanks

 

[Gregory Paolini]

I generally spray shellac with a 1.4mm HVLP gun. I usually set my supply air to 40psi, and then adjust the gun internally for the propper volumme, and fan. Believe it or not, the Harbor Freight gun which regularly goes on sale for $15 does a good job of laying down finish, although you need a high volume compressor which can keep up with it...

Just keep in mind that spraying shellac is essentially weilding a flame thrower that's just waiting for an ignition source. Luckilly, You can spray it outdoors in just about any temp above freezing, if you don't have a dedicated & approved spray booth.

Hope this helps!

 

[Bill Clemmons]

I use a gravity feed HVLP gun. Sorry, I don't know the tip size. I regulate the air right at the gun, and generally run at about 30-45 PSI. I've got a 5 hp, 60 gal compressor, or adequate pressure is not a problem.

I dilute the shellac to about a 1-1.5 # cut.

Spraying shellac creates a lot of overspray, so be sure to wear a good respirator and eye protection. If you wear glasses, either take them off or clean them quickly w/ DNA. Your shop will appear very foggy if you don't. :rotflm:

HTH

Bill

 

[kooshball]

Thanks guys; good to hear that the affordable gun is likely to be sufficient.

I will test my glycol ether addition on the bottom of the top this weekend and see how it goes; if it goes poorly I'm off to harbor freight!

 

[JonT]

I generally spray shellac with a 1.4mm HVLP gun. I usually set my supply air to 40psi, and then adjust the gun internally for the propper volumme, and fan. Believe it or not, the Harbor Freight gun which regularly goes on sale for $15 does a good job of laying down finish, although you need a high volume compressor which can keep up with it...

I second that recommendation! I've been refinishing autos (and electric guitars) for years using the HF HVLP gun. It does a wonderful job with every different finish I've put through it (lacquers, catalyzed urethane, enamels, etc.) and IMO is one of the best values in that store.

one tip -- be sure to run a water trap (tangerine color & size filter) before your gun or you'll get nasty condensation in your finish.

 

[junquecol]

HF currently has that gun on sale for $14.99. I picked one up on a friends recommendation on Friday night. Used 20% off coupon. If you need a coupon, let me know. Each Sunday there is at least one in the paper, and my wife's parents save me theirs also.

 

[Jeff]

As an organic chemist I'd be suspicious about the degree of solubility of shellac in glycol ethers. The "lac" in shellac are carboxylic acids which may not have good solubility (add too much ether and the whole solution may just gum up because the acids begin to precipitate). It'll be interesting to hear/see the results of your test. A possible solvent choice could be 1-propanol; it won't evaporate as fast as ethanol because of its higher boiling point (97 degrees centigrade) vs. ethanol (78 degrees C).

http://usm.maine.edu/~newton/Chy251_253/Lectures/Solvents/Solvents.html

If you don't have a compressor you could consider a stand-alone HVLP sprayer. The Earlex 5000 system runs at 2 psi and with the optional 1.5mm tip it'll do a good job with shellac (1 lb cut) and Waterlox "Original" (without dilution).

http://www.amazon.com/gp/product/B0..._m=ATVPDKIKX0DER&pf_rd_r=1WB2B4VVJ1DYBHK5JDJ0

 

[kooshball]

As an organic chemist I'd be suspicious about the degree of solubility of shellac in glycol ethers. The "lac" in shellac are carboxylic acids which may not have good solubility (add too much ether and the whole solution may just gum up because the acids begin to precipitate). It'll be interesting to hear/see the results of your test. A possible solvent choice could be 1-propanol; it won't evaporate as fast as ethanol because of its higher boiling point (97 degrees centigrade) vs. ethanol (78 degrees C).

So far I am getting favorable results but I don't think that am putting enough in to kick anything out of solution. At the moment I made a 1.25lb cut of shellac, then added 2% (by volume) glycol ether to this cut. it seems to give me just enough open time on the sides of the dresser to level well and not drag.

The big test will be the underside of the top and if I need to go up on the glycol ether. I am using a 100% Chinex 3" brush that really seems to flow the shellac well, so maybe I will get lucky.

Either way I picked up a HF gun that should run well on my compressor (as long as the manual is accurate) so I can spray if my experiment fails.

Regards

 

[Jeff]

David,

Sounds like you have a good handle on it to suit your needs so carry on and best finishing. :eusa_clap