[IFlyShamu]

I am painting a duck tail spolier and chin spoiler for my 2005 Mustang GT and wonder if I am screwing things up. The parts are urethane plastic. I am using a HVLP gun that I know nothing about. I have used an older type of sprayer before but that was 11 years ago.

I block wet sanded the parts with 320 and then applied a few coats of Omni AU 2k Urathane Surfacer MP182 mixed with MH 165 hardiner. I then block sanded with wet 400 and I do not remember if I shot another coat of surfacer or not before I shot the color. The color that I used was Omni AU MBC (black) mixed with a MR series reducer. 3-4 coats of color were applied but I was not real happy with the job. The paint seemed like it came out in globs and not in a mist like I had been used to seeing.

I did not read the tech sheet for the Omni paints but I read somewhere on these boards to not clear until after 48 hours. WRONG!! I finally did read the PPG tech sheets and they say clear within 24 hours. So I had to resand and recolor and this time I liked the application. I must have screwed up and got the gun set to the proper setting.

This is where I think I really screwed up. When I opened the clear (Omni AU MC 161 High Solids Urethane Clear) I noticed billions of air bubbles suspended in the clear. I shook the stuff and that is where the bubbles came from. Should I have stirred it instead? I waited the recommended time between color and clear before I shot the clear coat. The clear application was more globby than the base coat. I flashed the recommended time and applied a few more coats. The clear looks like crap. Those pesky bubbles are everywhere.

I hope I can sand the clear down tomorrow (16+ hours after painting) and get some of those things out and then recoat it with clear.

Am I on the right track or have I totally screwed it up?

 

[MIKE FROM SM]

Sounds like too little of air pressure. How much were you running?

 

[IFlyShamu]

The gun says 10 PSI MAX so thats what I was running. What would you recommend? Can I sand down the clear coat and reclear it at a higher pressure?

 

[OneMoreTime]

It is really important with a new gun to spray some layouts to get the adjustments correct..tape a piece of masking paper to the shop wall and adjust until you have no orange peel or runs then shoot the part..you should be getting a nice even coat of material..

Also read your cheat sheet that came with your gun..hope you have one and set it up accordingly..HVLP is a bit different than what you are used to..


Yup sand it out and reshoot..hopefully it works out this time..

Sam

 

[Beenaway2long]

I found that I needed WAYYY more air pressure than what it called for. Otherwise, it came out in globs. Looked like concentrated paint spatter.

 

[MIKE FROM SM]

That is 10psi at the cap, which is something like 35-45psi at the guage.

 

[tthomp]

it probably says 10psi max at the air cap....... try between 35-40psi at the air inlet......

 

[IFlyShamu]

Thanks guys, I will raise the pressure and try it again. Now, its off to sanding!!

 

[IFlyShamu]

The more I live, the more I realize for every day that I advance, it takes me a week to accomplish it.

I started sanding down the clear coat and one corner of the base coat pealed up. I was able to completely peal up the base coat on all of my pieces. No need to sand down the clear. The color was not sticking to the Surfacer coat.

Reading the product information sheet PPG Omni MP182 2K Urethane Surfacer it states that the drying time is 2-3 hours before sanding and overcoating. Does it have to be sanded before top coating? Do I need to sand the surfacer with 400 dry or 800 wet before I shoot it with color base or can I just shoot the base with out sanding? I cant find 800 wet, can I use 600 wet before the base color?

Thanks again.

 

[IFlyShamu]

I now realize that that it takes me a week to accomplish a days work.

As I was sanding my parts down, a small area of color paint pealed up. I picked at the area and was able to remove all of the color base coat this way. It delaminated from the surfacer primer coat. More questions.

The Technical data sheet for the MP182 2K Urethane Surfacer says that the air dry time is 2-3 hours before sanding. Then the Sanding and Topcoating section says you can sand with 400 dry or 800 wet then base coat it.

My question is do the parts have to be sanded before the color base coat gets applied? I don't think I did this and that is probably why I was able to peal the last job off of the primer coat.

Thanks.