Powder Coating chipping?

[dsacco1013]

Am I not getting good adhesion or is that the nature of the beast? I am spraying it, it might be on there a bit heavy but after it cures it looks so good. I thought maybe it wasnt curing good enough because the IR light will only get the part to 300. It does flow out drys nice and looks great the only thing is that it does chip fairly easy.

Dave

[Hemi-T]

How did you prep the part? It may be that your chipping problem is caused by poor adhesion from improper surface prep. I sandblast, apply powder, and cure. Powder coating is known for it's resistance to chipping.

Hemi-T

[drfjr1976]

I was going to say the same thing Hemi-T It could also be that it is not completly cured. I would check to make sure the part was properly preped first.

[dsacco1013]

That is what I thought. The first piece was a piece of one inch square tubing bare I just wiped it down with thinner. That turned out alright 1 to 10- 10 being good it was a 7. Second piece was a bracket bare metal, I sanded down with 220 that was about a 6. Third piece is a receiver hitch pin bare sanded and wiped with thinner, adhesion a 4 looks an 11. 7...6...4...See where thats going don't you! Thanks HemiT for backing up what I thought about the "Hammer tough" coating. I am going to try to sand blast something tomorrow.

[tomg552001]

Yep, its under cure, or improper prep.

[dsacco1013]

drfjr1976 if the IR light wont get the part to 400 for 14min ...will say 275-300 for 20 min do the same thing?

[tomg552001]

If the temp of the lamp won't go higher than 300, cure much longer. Depending on what you're curing, i'd go for a good 35-45 minutes or so. Or maybe 25-35 once it starts flowing. Better safe than sorry, and its hard to over cure powder at that temp.

[dsacco1013]

Ok here is the plan.....Tomorrow
1st find a part
2nd sandblast it
3rd wipe with thinner
4th cure 35 minutes on each side

Can I over cure?


Thanks guys.

[tomg552001]

From what Russ says, you can not....unless you cure it in a burn off oven maybe . Your plan sounds good....you may even want to go longer if you're coating a dense, thick part.

[dsacco1013]

Sounds good guys. I will update yez guys later. (It's a pittsburgh thing)

[Fireblade]

Surely sounds like undercure to me, as said before. I think prep would cause different types of problems other than chipping off, maybe peeling off but not a chip like in paint. 35 to 45 mins is a long time with a IR lamp, ya sure ya wanna go that long?? If you look at temp and time curve with the Ir lamp, it is much shorter than a oven would be. I would try moving the light closer to up the heat, maybe a bit longer on time, but not that long. Just my opinion.

[DALE]

These guys are right on prep and to me it sounds like under cure.
Yes you can overcure powder, You will notice shade differences from part to part if cure cycles vary alot. The quality will still be there as far as durability though. Differnt powder formulations resist overcure differently.
This is most noticable with light colors.

[non-stick]

once again I concur with you guys in all that you say. I have nothing to offer this post other than a "hope ya learned something from your bretheran.... they all hit the nail on the head,basically". Well done indeed guys. I like the unity and helpfulness you guys share with one another. Small group (but growing) and tight knit. You're all well on your way to being tops in the hobbyist field (if not above!)..... Russ