What happens to PC when it is past the 6 month storage time?

[Fireblade]

What does the powder do, if you spray it after the 6 month storage time it recommends? Is there a chemical link that no longer occurs? Different for different types of powder?

[non-stick]

it realistically depends *how* you store it for 6 months in all reality. If kept in an air-tight container and the negative volume is filled with inert gas such as Nitrogen..... it will keep in stasis for quite a few years. If you keep it in a paper bag and outside in a shed...... then your shelf-life will be weeks. The main killer here is moisture. Inevitably, polymers pick up moisture from the surrounding air. It's not unusual for platic packaging suppliers to pay more for shipping in the humid summer months due to weight than in the winter when it's bone dry, oddly enough. Powder reserved for coatings are no different. Eventually they gather moisture from air surrounding you and become so laden with it.... they no longer hold as good an electrostatic charge or "clump" together and become very cake-like. Therefore, they don't like to stick, flow as well, or give up thier properties chemically anymore. Keep your powders in an air-tight container if you can. Also.... evey so often, "shake" them in that container to avoid excessive clumping. Even under the best of conditions, I wouldn't trust many powders past a year or so in storage just because it's cheap enough to get another pound of "fresh" and deal with it that way. Hope that helps.... Russ

[etyrrany]

Based on this very fact I was contemplating some type of plexiglass enclosure for my powders. Completely sealed with some type of valve on it so I can suck out the air with a vacuum and store my powders. When and if I decide to go this route (mainly $$$) I'll post some pictures.

etyrrany

[non-stick]

I'd only suggest that if you do that.... you put in some sort of sacrificial medium to take any moisture out. Surrounding environment in a negative pressure with moisture is still an environment with moisture, my friend. In all actuality... you're opening up the "pores" of the powder so that when you make positive pressure again.... they will be more susceptible to gathering humidity. Try taking something simple like kitty litter and put it in an open coffee can along with the powder or perhaps one of those new arm&hammer baking soda boxes that are made with the "flow-thru" panels in them in the chamber along with it. Change it every so often and you should be ok. The point is to make a medium more attractive to moisture than your powder is. Much like a sacrificial annode is in your cooling system as opposed to the aluminum in your cyl. head if that helps any..... Russ

[DALE]

I have easily stored powder for up to and over 6 months. If fact I have one box that is almost a year old and we still get great results with it.
Everything that comes in to my shop gets sealed inside heavy mil plastic bags and then sealed inside another bag. We then place the bags inside metal cabinets to stop any UV breakdown. One hint also keep away from doors, windows,ovens,furnaces, and air conditioning units. The temperature swings will kill your powder rapidly due to condensation.
Moisture is your biggest enemy for powder so don't set it on your concrete floor or near you wash tank. Good hygene and common sense will keep your powder good for many,many months.
As for the What does it do question, it will be difficult to get the powder to take any charge. You will see it blow right by the part with no attraction. Also if you sift it with a spoon and its not light and fluffy or clumps onto the spoon it's gotten moisture. One use for this instead of throwing it away is save it for parts that aren't important, it is still good powder once baked on. Get the part up to350 or 400 bring out and spray instantly this will allow the powder to melt on thus needing no charge watch out for putting too much on though it's easy to do.

[duke]

i think this would be the most informative, helpfull, & unselfish forum on the internet that i have seen, bar none
i hope you guys keep up the good work & don't get tired of helping newbies like me, cos that would be
cheers

[Fireblade]

My thoughts exactly Duke. I have read the warnings on the powder containers, but they never said why. Now I know, but I can't say I have ever seen any of the negatives happen to me with "old" powder. I had some gloss white sitting around forever, I bought it when I first started PCing almost 2 years ago, it was to go back the color in case I didn't like the color I was changing the parts to. Needless to say, the new color worked great with my plans and the white had a home on the shelf, worked like a charm about a month ago when I finally yanked it and used it. Thanks for all comments from everyone, now I know.

[ShelbyCSXT]

Has anyone ever thought of putting silica gel packets into the powder containers? Everytime you use a powder, you could bake the silical gel to remove any moisture so that it's ready to go when you are done PC'ing with that particular color.

Texas Technologies has quite a few goodies.

[defed]

texas technologies!?!? boooo!!!

my brother works at a place (not texas tecnologies ) that manufactures these silica packets, gel caps, etc...they make so many products i don't even know what they all are. sometimes he brings home a bag of the material if we need it for something and i thought about it when i started reading this thread. the stuff he had last was blue, and gradually turned pink as it collected moisture.

[mcaswell]

If you have purchased powder from us in the past 2-3 weeks, you'll find that we have been packaging our powders in a can ( to keep out moisture) and inside the can is a - wait for it ---- silica gel packet.