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My first attempt at spraying acrylic enamel was bittersweet. One good piece, one bad. What happened? The acrylic on the second piece was drying before it hit the metal (dusty, gritty finish)...maybe I was holding the gun too far away. or..... I didn't have the reducer at the correct proportion. I used a 1 part paint, 1/2 reducer at 50 psi. Any ideas on what I'm doing wrong. The first piece turned out well, the second has been re sanded and ready to go again...I just want to correct the problem. The only thing I did different on the second piece was I added a little more reducer. The temp was around 80 when I was spraying. Thanks for your help.

It could be any number of things that caused your problem. You could have used the wrong reducer for the temperature, your gun could have been too far away from the object you were spraying, not enough reducer vs. material, air pressure incorrect for the amount of fluid flow, fan spray width incorrect, fluid control knob not adjusted correctly for the amount of material for the fan width and air pressure, and etc.

All of the above have a direct relationship on each other so to get the material to flow out correctly you will probably have to do some experimenting to find what will work for you at the temperature at which you are spraying.

are you sure your air pressure is correct it sounds high , are you spraying a solid or metallic color.

1 part paint and 1/2 reducer. That sounds awfully funny to me. I've never sprayed any a/e that has called for that mix. Pretty hard to give you an idea where you went wrong without knowing the make of paint, gun type,reducer and type of reducer. if you can give us that info it would really help. Cheers!!!!

According to the specs. by PPG, acrylic enamel should be reduced by 50% and sprayed at 55-60 pounds air pressure at the gun.

I am using a Delstar engine paint from the Filling Station on my 25 K coupe engine. I had just started the project by painting the bell housing and that's when the problem developed. I haven't started the engine painting yet and want to make sure all the bugs are out of the system before I do. The reducer is Delstar also, DTR601. My gun has performed well on past projects with enamel (oil based). It is a small touch-up gun (holds about 4 oz of material). Not sure of the brand, but know that it is not an expensive gun. I had heard that 40-60 psi was the correct pressure and the reducer could be from 1/2 to 1 part for part of acrylic enamel. Thanks for all your experience and suggestions.

Two thoughts come to mind. First, a damp and humid day will help enamel flow and keep it from drying too fast. Were the two parts sprayed on different days? At 80 degrees you should probably be using a slow reducer.
Secondly, and perhaps more importantly, there may be a math error. If the specs call for reduction by 50% as JYD says, then your "1 part paint and 1/2 reducer" does not equal 50% reduction. To get to a 50% reduction use 1 part paint to 1 part reducer.
By the way, that engine paint from Filling Station brushes on very well straight out of the can, especially on cast pieces such as the bellhousing and engine. Stamped steel pieces such as a valve cover are probably better when sprayed.

Coach

"To get to a 50% reduction use 1 part paint to 1 part reducer."

I believe that is 100%, not 50%. For example, for one quart of paint one pint of reducer should be added for a 50% reduction (One-half of one is 50%). For a 100% reduction one quart of reducer should be added to one quart of paint which is one part paint to one part reducer.

PPG states on the can that for one quart of enamel it should be thinned with one pint of reducer (50%).

Lacquer is reduced by 150% which means for one quart of paint three pints of lacquer thinner should be added.

DTR-601 should be used for temperatures between 60 and 75 degrees. You mentioned that you were spraying at 80 degrees, so for that temperature you should use either DTR-602 (70 to 85 degrees) or DTR-604 (85 degrees and above). I would go with the DRT-604 which would allow your paint to flow better.

The other problem I see is that a small touch up gun is being used. It is probably to small for the job and it doesn't put out enough CFM with a wide enough spray or enough material.

I have found that the engine paint from the Filling Station is ready to spray right out of the can with no reduction needed. However, on the flip side of the coin I have found that the engine enamel from Chev's of The 40's should be reduced some for better flow capabilities.

I stand corrected; must have been one of those morning brain cramps. Math in the morning is not a good combination, and I should have known better then to go there.
Coach

bacchus10 you didn't mention what kind of spay gun you have; if you have a later HVLP or LVLP gun then the pressure at the gun should be max 30 psi (usually for primer or 25 psi for color coats) and 10-12 CFM air flow. Early HVLP guns used 50 to 70 psi inlet pressure and 18 to 22 CFM air flow. A dirty gun from drying paint will look like a rough and chunky surface finish. When spraying with any of the HVLP & LVLP guns you should be approximatly 6 - 8 inches above the surface to be painted. HVLP guns are also sensitive to the travel speed across the panel to fast and you won't get enough paint on a bit to slow and here come the runs.

Eureka!!!!!!!!!! I repeated my attempt to spray the bell housing and it WORKED!!! The bell housing turned out perfect. I worked on the volume,and psi to get it perfect. I ended up spraying at 55 psi with the paint coming out of the nozzle perpendicular to the air outlets. I asked an old car painter what his secret was to painting with acrylics and he said, without hestitation...."just keep your gun at a distance that equals your extended thumb and little finger spread apart" and "adjust your volume so it is perpendicular to the air outlets on your gun". He added as you guys added, " temps are important, he said, "I just spray a piece of cardboard to see what my gloss is going to be and adjust so I don't get any of those dust bugs". Viola, it worked. Thanks to everyone for your suggestions. I really appreciate this forum...what a myriad of knowledge to help us neophytes out!!!!

Cool! Glad that everything worked out for you. Yep, increasing the pressure does make a big difference when working with enamel.