One last question about nitro (I hope) - created 03-05-2007

Ezzo, Steve - 03/05/2007.20:51:06

What lacquer/thinner/retarder ratio do most of you experienced nitro-finishers use? I'll be shooting in 65deg.(+/-) weather and

65(+/-)percent relative humidity. Sato Mini Jet 3 gun (HVLP). I'll use a heated box for drying and curing. Thanks in advance for your help!!!!!

I might suggest spraying some scrap wood with "full strength" lacquer to see what the gun does, then add thinner until you get good results. Pour that lacquer through a viscosity meter, and write down the results and the proportions. You were recording the proportions as you added thinner, by the way.

As for retarder, use what you need. At 65% RH you might need some, but how much will depend on the speed of the thinner that you are using.

Ultimately, you'll have to figure the mix out for yourself because you're combination of lacquer formulation, thinner speed, retarder, spray equipment, and atmospheric conditions is unique.

Now for how I do it:

I mix thinner into the lacquer by eye. I stir the lacquer, then watch the lacquer run and drip off of the stir stick. When it looks right, I spray. I normally add a "dash" of retarder just to get better flow; more if it's humid and if I have any blushing problems. If I don't like the way things are going while I'm spraying, I'll sometimes stop, add thinner or retarder to the lacquer, and resume spraying.

I don't get too scientific about my finish mixing, but that doesn't mean that you shouldn't. Measuring viscosity is a good idea.

I mix thinner into the lacquer by eye. I stir the lacquer, then watch the lacquer run and drip off of the stir stick. When it looks right, I spray.

I was taught to add thinner until the stream coming off the stir rod breaks up into individual drops.

I was taught by a rather excellent car painter to only thin as much as my gun needed in order to shoot smoothly, no matter what the material, no matter what the weather. That lesson has carried me this far, and never let me down.

> I was taught by a rather excellent car painter to only thin as much as my gun needed in order to shoot smoothly, no matter what the material, no matter what the weather.

Same here... and with my gun and every Nitro-Lacquer I've tried so far has been straight lacquer with no thinner.

Nathan, Would you mind sharing the gun set up and brand lacquer you use for spraying straight without thinner? I'm a rookie who has yet to invest in a gun and would appreciate the feedback. I only plan on doing a few instruments before I decide if I am going to continue to build.

Behlen's Stringed Instrument Lacquer, Watco, Parks, McFaddens.

I have very good luck with my cheapie Campbell-Hausfield jamb gun. So much that I've not felt the need to upgrade.

I use behlens stringed instrument lacquer, It works good for me without any thinning--although I do thin the flashcoat 50/50--after that I use it right from the can after straining it through a piece of mothers old wore out nylon hose.

Many nitrocellulose lacquers do come "pre thinned". Thinner is cheaper than solids. A finisher friend taught me to use a 4 count. Most of the lacquer should run off the stirring stick, and start dripping (rather than a continuous stream) within 4 seconds. That method gets you in the ball park.

Great gun. I used to shoot straight, in 75%+ humidity with no ghosting (@ 78 degrees F +). Humidity is hard to get away from here, so is warm weather. 1 hour between coats, 3 coats a day.

Anyway, I still shoot straight for the first 6-9 (depending on wood), then 50% for the finals. With the Sata, I can start sanding @ 800 off the gun from the final coats. If you're orange peeling too much, thin it out, and spray wet (as you should anyway). 4" distance on the HVLP works much better than 6"-"8" on conventional guns. If you run, you need to move the gun.

To add to Mario's statement - your gun will tell you what to do with your mix, assuming its properly set up, and you have enough volume of air coming through.

BTW, this is with McFadden's. And the main thing? Have fun! Aloha.

Excellent! I believe Wood Craft has the Watco on sale this week. I was considering the Behlens stringed instrument lacquer until that came up. How does the Watco compare with Behlens?

I like the Watco much better than the Behlen's. The Behlen's seems a bit soft and for longer than it should which causes it to take forever to cure out for buffing, (It does polish very nicely though). With using the Watco and a proper pore fill, the last 3 intruments that I've sprayed I was able to buff in about a week and they still look great. It's dirt cheap too, dries hard, cures fast and buffs very well and I can get it at the local Menard's store.

I've used lacquer un-thinned with good results, but I have had a few times where the lacquer would not lay down and I got an orange peel look. Now I add just enough thinner to get the flow, far less thinner than I used when I started to learn to finish with lacquer.

I can't make any other recommendations as our local climates are totally different.

I have sprayed nitro straight, thinned in many proportions, at many temperatures, with different spray guns, and never could figure out why it was necessary to thin it. If I thinned it, it just took that many more coats to build. So, I went back to straight. I've also never understood the concerns about orange peel. I end up sanding it flat regardless of how well the finish flowed out (Nitro lays down better than any finish I have ever used). Not much more effort when it has a little orange peel, if any. I'm not criticizing anyone's approach, I just found the use of the product easier to do than to read about.