Spraying Lacquer Viscosity

[AMF]

I've always had a bit of trouble putting a finish on my works. I like the advantages of spraying lacquer because it is quick and leaves a nice finish. One problem I have recently encountered while lacquering at home was getting the consitancy (or viscocity) of the lacquer right. I have a Viscosity cup but have no idea what to time it at. If I remember correctly from automotive painting, the paint should "drip" in a steady stream off the end of the stir stick. Is there something like that to get me in the ball park so I can then measure the time with the Vis. cup and have a standard? Any help is greatly appreciated.

Alex

[old_guy]

I've always had a bit of trouble putting a finish on my works. I like the advantages of spraying lacquer because it is quick and leaves a nice finish. One problem I have recently encountered while lacquering at home was getting the consitancy (or viscocity) of the lacquer right. I have a Viscosity cup but have no idea what to time it at. If I remember correctly from automotive painting, the paint should "drip" in a steady stream off the end of the stir stick. Is there something like that to get me in the ball park so I can then measure the time with the Vis. cup and have a standard? Any help is greatly appreciated.

Alex

The instructions that came with my HVLP sprayer say that the contents of the viscosity cup should drip out in 8-20 seconds. I imagine, however, that every manufacturers' viscosity cup is a slightly different design.

The instructions went on to say that every finish is different with further variations between manufacturers. As a general rule, they suggested that lacquers be diluted to 1 part solvent -- 2 parts lacquer.

I might suggest that you start with this ratio in a small portion, and adjust based on how it seems to work for you.

[AMF]

Thanks, at least I've got a starting pint now!

[Don]

Hey, AMF. Old Guy has it, laquer is usually cut more than anything you're used to, mostly because when spraying the solvent is actually flashing away before it hits the surface. You almost can't go wrong when thinning laquer except for simply making it too thin, then it will simply not stay in place while drying; i.e. you are spraying mostly thinner. But, unlike other mediums, laquer is not harmed by too much thinning. Simply keep thinning until you get the spray consistancy and lay-down that you like. Once you have that, you'll know what you are doing and have confidence.

all the best, Don

[AMF]

I started spraying tonight again, so far so good. Ill report back with my ratio ASAP

EDIT: I Sprayed with a Gravity Feed HVLP gun at 50psi. I mixed the lacquer at a 1/4 ratio of thinner to lacquer. Where I purchased the Lacquer they said I could spray it as is but I found that it flowed alot better with a bit of thinner. Thanks again for the advice! I am now confident I can spray.

One issue I did have was 2 of the stain sample I was spraying got "fish eyes" over the stained portion, where there was no stain there were no problems. It was an unusual thing because I used the exact same stain on another board I finished today and no probs...any advice? assume I got some grease/oil on the rag at somepoint but my shop is clean...

[jcclark]

I usually thin my lacquer 50%, 2 parts lacquer to 1 part thinner.
The tip size on the gun will make that vary.
the larger the tip-the thicker it will spray.

I have started useing urethane reducer instead of lacquer thinner
for my thinning, it's much more expensive but gives a better finish.
I was advised to try that by a paint chemist who said it was ok
and worked better. I think it does.:cool:

[AMF]

Thanks for the info, Ill give that a try

[jcclark]

Another big help with lacquer is "retarder"
That helps a lot in hot weather to slow it down, especially
when spraying inside a cabinet.
I like to add some to my last coat and it will melt everything down
smooth and kill the overspray.
In hot weather it will stop any blushing, lacquer tends to do that.
It doesn't work real well with flat finishes, it tends to make
it shiney.:cool:

[jcclark]

OK, Where did everybody go????
Surely someone has some woodworking to share.
(I'm getting lonely out here):D

[Don]

It's slow everywhere right now, plus cold in most of the country. I guess most are staying out of the hobbyshop and by the fire. I've got some good stuff to share but I've been too busy to post, will soon.

dawjr