Looking for Help with Spray Gun Adjustments

Today I primed the hood/tank unit. I've been stripping a part at a time. The problem I'm having is that while I'm getting good coverage, I'm getting a dry, almost sandy finish - rough and granular particularly on the sheet metal. Cast isn't as bad, maybe because it is rougher to begin with. Could there be a temperature influence? - today was hot - other times I have gotten a much smoother finish without any changes, but don't know why.

The directions call for 5:1 ratio between paint and hardener. I haven't been using any thinner. Should I be? How would I know how much? And I'm not sure what adjustments I should try to fix this problem. More/less air?, more/less paint?While I can sand down the primer now, I sure need better knowledge how to make the necessary adjustments before I actually try the top coat.

Any help would really be appreciated! Thanks

I've seen line regulators that fit on the gun inlet - do you think it would help to put one on?

I stripped the sheet metal, cleaned with metal etch, primed with rattle can etch primer compatable with the 182, and then sprayed on the 182 after some body work. I used the can primer because I was only doing a part or two at a time and I wanted to protect the part, and didn't want to clean the gun each time. Next time I'll use the 170 epoxy but too late to switch now.

I'm more concerned with getting the right technique established before I get to the final painting stage. I'll try the set-up sequence you described.

Thanks

I am not familiar with your gun and setup so I can't advise there. However, the MP182 is NOT intended by the manufacturer to be reduced (thinned). There is no material specified to use even if you wanted too. Here's the tech sheet for the 182. There are two different hardeners to use, depending on ambient temperature at time of painting. The MH165 is a fast hardener that is best used in mild and cooler temps and the MH166 is a slow hardener that would do better in warmer temps. There are no specific temps mentioned by the manufacturer but if it were me, I would use MH166 above 75 deg F and MH165 below that. If you are warmer than about 75 and are using the MH165, that could be your problem as it would tend to yield a dry spray. Other things that might cause a dry spray would be to much air for the fluid flow. If there is a way to change that relationship with your gun arrangement, I would try more fluid and less air. If you have interchangeable fluid tips and needles, try a larger combination. Also, too great a distance from the part could be another cause. Try staying no more than 6"-8" away from the surface. Too fast a movement could also be an issue. Try slowing down your speed. The mixture also has a 1 hour pot life so make sure you use it within an hour (at 70 deg) of mixing.

You might want to consider a straight primer like the MP170 epoxy as a better direct-to-metal primer for both the sheet metal and the cast. The 182 surfacer is better utilized as a surfacer only rather than a combination primer and surfacer. The cast generally doesn't need a surfacer at all and the sheet metal would be better served by using the 170 as the primer and the 182 on top as a surfacer, if needed.

I would also recommend practicing on a piece of scrap sheet metal until you get a better hang of things. It might well be worth the few dollars to actually buy a 3 or 4 ft square piece of sheet metal to practice on (in the vertical position). That's what I did when I first started. You should get your confidence up before you actually tackle your tractor parts.

Rod

I appreciate the information and suggestions. I'll try the slower (166) reducer - it was in the high 80's here in NJ yesterday. Seems to me that the days I got better surface were last fall and were cooler. I do have a larger tip set too so that will be another thing I'll try.

Next project I'll go with the epoxy primer (170)you recommended. The sheet metal practice sounds like a good idea, particularly till I get the combination right. Thanks

Paul