Light around the edges... What does this mean?

[Guest]

I've been meaning to ask this for a while and I'm really curious to see what causes this... Every once in a while I'll coat a part with sharp edges. The part looks like it's evenly coated prior to entering the oven, then after the powder flows out these sharp edges appear to have very little powder on them. This becomes extremely apparent on translucent colors that really show their base coat.

What causes this? I've given it some thought and I can see it being many things, mainly one of the following two...

There is just not enough powder on the edges.

Powder is flowing out too quickly and not quickly enough.

It can usually be resolved with a second coat, but this is really not the way I want to take care of it. I would rather find out the cause and get it right the first time around.

Thanks for the advice!

Juan

[BeeBob]

Re: Light around the edges... What does this mean?

The main problems are the sharp edges and "thin" powders. You can ( IF customer doesn't mind! ) slightly round the edges, give the edges an extra shot of powder or the whole thing a 2nd coat. Trans and candies seem to be the worst.

[Guest]

Re: Light around the edges... What does this mean?

That's exactly what I'm coating with right now... Transparent blue and it looks great everywhere except the edges. Unfortunately there is no way I can round the edges as it involves precision parts such as a blow off valve and throttle body.

I really suspect the heat-up time as part of the issue. Could heating up the fast too slow or too fast cause this problem during flow out? If so, which is it?

[wiseguyz]

Re: Light around the edges... What does this mean?

If you read up on the different types of powder, that is just a characteristic of some. Polyesters give better edge coverage than some of the others, but you will notice the light edges on transparents or candies because they are in effect just tinted clears, so anywhere the coverage is thinner, the color will appear slightly lighter.

[Guest]

Re: Light around the edges... What does this mean?

Here's what seems to be working well so far.

1. Shoot base coat (silver explosion) and fully cure.

2. Cool base coat to ~120 degrees.

3. Shoot heavy but even coat of transparent.

4. Fully cure for 10 minutes at 400 part temperature.

5. Cool second coat to room temperature.

6. Shoot light top coat of transparent.

7. Preheat oven to 200.

8. Cure top coat for 11 minutes at 400 part temperature.

Figured I would list the steps in case anyone else is looking for a solution to a similar challenge. I'm sure there is more ways to go about it but this seems to work for me!

[Guest]

Re: Light around the edges... What does this mean?

4:30AM and I'm need of some serious sleep. This has been an extremely frustrating day and it didn't end in success... Just not a good day of powder coating. I'll leave you all with a question though... any problems with shooting bumper black or any other black over a transparent blue top coat? Thanks!

[wiseguyz]

Re: Light around the edges... What does this mean?

Juan]4:30AM and I'm need of some serious sleep. This has been an extremely frustrating day and it didn't end in success... Just not a good day of powder coating. I'll leave you all with a question though... any problems with shooting bumper black or any other black over a transparent blue top coat? Thanks!

We all have days like that, Juan. Tomorrow's another day. And you shouldn't have any trouble going over the blue as long as your gun is capable of multiple coats.

Best of luck.

[Guest]

Re: Light around the edges... What does this mean?

Juan]4:30AM and I'm need of some serious sleep. This has been an extremely frustrating day and it didn't end in success... Just not a good day of powder coating. I'll leave you all with a question though... any problems with shooting bumper black or any other black over a transparent blue top coat? Thanks!

We all have days like that, Juan. Tomorrow's another day. And you shouldn't have any trouble going over the blue as long as your gun is capable of multiple coats.

Best of luck.

Well tomorrow was a MUCH BETTER day...

Woke up early and got a jump start on last nights project. Customer decided to go with his second choice color for the intake manifold so I shot black over the blue. I'm actually VERY impressed with this little gun. I managed to lay down a good layer of silver, then 2 of blue, then 2 of black without any big issues.

Once that was out the door it was time to start on the next candy project using transparent red and silver explosion.

This color is WAY more fun! Still required two coats to give it the right look, but it flows out very nicely!

Here's a quick shot of one of the intercooler pipes...

[Guest]

Re: Light around the edges... What does this mean?

The Silver Explosion is a great base coat for any Candy...the most difficult task of the custom coater is to learn how to wotk with the different characteristics of different powders...

[Guest]

Re: Light around the edges... What does this mean?

Great job Juan. Very nice!!
What gun are you using?
Harley