What did I do wrong?Pearl white???

[mx3twinturbo]

I have a customer who wanted his whole engine coated in Pearl white,
I preped and pre baked all the parts, coated the engine and this is what happend
I am using the HotCoat hobby gun, and Caswell powder I'm thinking I didn't apply enough powder but... what do you guys think??






Thanks for your input

[mx3twinturbo]

Re: What did I do wrong?Pearl white

[Harleydad]

Re: What did I do wrong?Pearl white

Can't see the pics?

[holeshot87]

Re: What did I do wrong?Pearl white

it looks like you need to use more powder. some spots look like u just miss them. no big problem. 2nd coat it.

[mx3twinturbo]

Re: What did I do wrong?Pearl white

I figured.

Thanks Jesse

[nuttyman]

Re: What did I do wrong?Pearl white

it outgassed. recommend using an OGF primer or OGF additive in your powder for similar jobs. also you need to sand down the first coat if you are going to re-coat over it or you will have unwanted texture in the finish.

[BottleFed70]

Re: What did I do wrong?Pearl white

it outgassed. recommend using an OGF primer or OGF additive in your powder for similar jobs. also you need to sand down the first coat if you are going to re-coat over it or you will have unwanted texture in the finish.

I agree, this is an outgassing problem.

Notice where the problem happens most is in the recesses near the gasket surfaces? Near the gasket surfaces is where the casting will be exposed to the most oils(and where the most outgassing would happen). The fact it's in the recesses tells me that the the part probably wasn't pre-baked for long enough to fully outgass. The recesses are the spots in the block that would have taken the longest to get to full temp.

May I ask what your pre-baking procedure was? An engine block will take a long time to get up to temperature. If I was doing the coating, I would pre-bake at 500* for at least 1hr, preferably 2.

If your pre-baking was that thurough, then I agree that the outgas forgiving compound is a good way to go (or just use it anyway for added insurance).

[PCT17522]

Re: What did I do wrong?Pearl white

I agree with what bottlefed70 said, it sounds logically sound. I also agree with holeshot87. When you're coating an extremely rough surface (like with a casting) you need to spray it thick enough so that the powder can "flow" into all of the pits and valleys during the cure. Corners, indents and recessed areas typically do not build thickness as fast as the other surfaces (due to the charged particals wanting to take the path of least resistance, usually referred to as the faraday cage effect), so you need to concentrate on them more while you're spraying. Since most of your problems were in this type of area, that's what leads me to say that it is at least partly a thickness issue. I would also pay close attention to the outgassing process, and use the OGF. Everyone seems to endorse this product so it couldn't hurt to use it.

[mx3twinturbo]

Re: What did I do wrong?Pearl white

Well It was out gassed for a long time at 500* about a 1 1/2 hours,
along with the rough surface finish on the casting I simply did not apply enough powder.

I also found my air supply very wet, I now fixed that, (added a Intercooler from the pump to tank) and added a water separator at the booth. why I didnt have one there in the first place don't ask.

The second coat turned out fine along with the head and brackets.

Thanks for the input I always find it helpful.