powder qeustion from a newbee

[420gixxer]

I purchased a kit from HF just to get started and I have all the other needed things. I have been experimenting with 6061-T6 AL. I have blasted and cleaned well with a good solvent and degassed the parts. My problem is no matter how long I bake the powder on the item, it never seems to have good "pencil hardness" or be very chip resistant and durable as it should be but it has a really high gloss and great look. Is this just the nature of the powder that I am using. I am assuming that it is polyester or polyeurathane. I got the powder from HF, is it just a lower grade of powder. Sorry for being so longwinded. HELP

[kchotboat]

are you baking it for 20min at 400?

[420gixxer]

Yes. I have been to both ends of the curing spectrum with temp and time I have been as high as 475 from 10 to 30 min. & as low as 375 from 20 to 45 min. all with various degrees of hardness but no where near the durability it should be. I have even pre heated. has anyone had these results??

[Popeye]

Baking 6061 ruins the aluminum.....

[jtagger19]

sounds like it could be a bad powder or a soft blasting
the stronger the blasting (rougher) the better adhesion .
I use 120 media at 120 Psi

[420gixxer]

Well I guess that I will have to go this alone and just waste some powder due to the limited replies
Thanx so far!!!

[customandsound]

all the answers can be found with the search button...

but like it was stated it could be a number of things.

1. bad powder
2. over or under cured
3. to smooth of prep work
4. moisture
5. and what popey said ... baking the 6061 alum. is a no it weekens the metal.
get your self some scrap and shoot the powder the more you do it the better you will get and your results will be out standing..

you want atleast 1-3 mil of coating ..

Good luck and enjoy the board

[420gixxer]

Thanx for the lead customandsound, I will keep the powder flowing and work it out!

[PowderVisions]

Re: powder qeustion from a newbee

I think your problem is entirely in the pretreatment or lack thereof: You said you cleaned the T-6 with solvent , which almost always has oils within it. This is not good for any powder. Try using isopropyl next time. Also, blasting it is ok, but I think you should be cleaning the parts with an akaline cleaner afterwards. This will make sure that the surface that sees the powder will be clean of all soils, including those you indroduced during blasting. Powder coating is much more than simply applying a topcoat. Sure, it look nice, but it will not have any performance without an adquate pretreatment. I sure hope all you old and new powder coaters start to understand this. Don't become discouraged because you missed a major step. This is easy to remedy, but most never think to accomplish it and many think they have accoplished it by cleaning with solvent, thinner or tap water as a rinse.

[sdold]

Re: powder qeustion from a newbee

Speaking of durability, which is more chip-resistant, thin coatings, or thicker? Is there a big difference?

[Popeye]

Re: powder qeustion from a newbee

Thin is less prone

[PowderVisions]

Re: powder qeustion from a newbee

The general answer is thicker coatings will be prone to chipping, however, you really need to go by the powder manufacturers specification sheets because each different powder is formulated to be applied to a certain mil thickness in order to get the maximum benefit. If you are under or over that spec, your part will either look bad, have poor performance or both.

[sdold]

Re: powder qeustion from a newbee

Thanks guys, I think I might have been be over-applying the powder on most of my jobs. I need to learn how to measure and control thickness. I just had a bike frame powder coated by a professional shop, and it seems thinner than the coatings I usually do.

[PowderVisions]

Re: powder qeustion from a newbee

Generally speaking, the thicker a coating, the easier to chip. In powdercoating, you really need to go by the powder manufacturers product specification sheet in order to have the best product. This sheet will tel you how many mil thickness the product need to have the optimal cosmetics and performance of the powder. If you stray from this specification, your topcoat will suffer either in cometics or in performance I.E., salt water test, UV test, tape test etc.

[c130herc]

Re: powder qeustion from a newbee

My problem is no matter how long I bake the powder on the item, it never seems to have good "pencil hardness" or be very chip resistant and durable as it should be but it has a really high gloss and great look.

I had the same problem at first but soon realized that I was counting the cure time from the time I put the part in. The cure time is from when you get flow.
I also had problems with the HF powder sticking, looked great but scratched/chipped easily. I would switch out your powder with some of Caswell?s powder. Use up the HF powder for practice on stuff that you do not care about how it looks in case you mess up.