*&%$@ Outgassing!

[KZjim]

I have an aluminum valve cover that is about ready to go into the trash.... I have prebaked it 3 times... soaked it in zep-a-lum and it still out gassed on me after i coated it! what gives?! anyone have any good sugestions?

[hvac36]

What temp are you preheating at ? Should be at least 425 to 450 then cure at cure temp of product. I preheat to 450 until valve covers reach temp then continue heating for about 10 mins then remove let cool to 150 then coat then place back in oven until cured..


Jim S...

[tavo1765]

I also have recently battled against a outgassing part.

Trick is to use outgass free powder, or make sure after you use the last cleaner to rinse the part with alot of water and air dry with compressed air, pre-bake for at least 30mins at 425.00 and pull out and let the temp o down to no less then 200f, and once evenly coated place in the oven with the temp at 285, once part gets to that temp ramp it up another 25 degrees let it hit that temp, repeat another 25, and repeat till you have reached 375 and allow it to cure for about 20mins if you are using a powder that requires a 400f cure temp....

Read the tips and tricks section "Non sticks post" which describes the same process. I cut and pasted what he wrote for you


For this example we'll be taking a common part such as an intake engine manifold and coating it. Something we can all basically associate with,right? We'll be using the hobbyist gun and say..... your basic black poly powder to coat with. Sound fair?(7-10 PSI and 20 KV on the volatge side)
First steps first....I'll assume by now you have prepped your part accordingly and have it all ready to coat. At this point is our first "tip" to coating aluminum. If you have degreased the manifold....make sure you have all the solvent out. "Solvent popping" looks exactly the same as outgas and needs to be taken care of in the same manner. Pre-Heat the manifold to a temperature of 250 degrees before coating to work it all out of the pores. Remove the piece and coat as you normally would any other metal....the pre-heat will not only solve the solvent dilemma, but attract the powder you are spraying to the part. All while this is happening, the pores of the metal have pretty much "gassed" themselves out by now and are willing to be filled with coating as opposed to air. Work quickly! Once aluminum reaches a point below 200 degrees, it likes to take the air back in, as it were. Put your part back in the oven and bake for the low temperature guidelines (lower temperature and longer time as per your directions). Lower temperatures for longer mean less of a chance of any other pores that havn't opened up yet to stay that way. Higher heat = more open pores. Plain and simple. Let the manifold sit in the 250 degree oven until the PMT has reached that point as well. Keep raising the temperature by 25 degrees and waiting a good 5-10 minutes (depending on thisckness of the metal) until the PMT itself matches the ambient air in the oven. You'll keep doing this until the point of your lowest cure temperature has been reached. Good..... now cure as per your directions (300 degrees for basically 22-28 minutes PMT sounds about right on a poly).

[jtagger19]

I outgass at 450 for 40 minutes then blast it then coat
never had any problems

also you might want to look for the OUTGASSING FORGIVING POWDER ADITIVE it's sold by tiger drylak it eliminates almost all outgassing problems
it's an aditive you add to any powder
they also have powders already made but not that many options.

[pdeinc]

I think the key to overcoming outgassing problems is to preheat ABOVE the cure temperature. I had been given some advice early on to preheat at 200-250 and that never worked for me.

[11111111]

i never have out gass issues, you need to clean better and make sure the part is up to temp when out gassing. i think to many people set the timer for out gassing and do 30 or 40 minutes but by the time it gets heat saturation ten minutes or more is waisted getting to temp and not out gassing. i use carb cleaner spray when i first load the part its fast and cheap then i crank it up. if i open the door to check on it before i shut the out gass procedure down i look for and smell for smoke. if it smells keep cooking. cool it two 200 spray and then ramp right back to cure temps. i never have problems and i believe it is all about not enough heat and poor quality cleaning. when you think its perfect wipe it down one more time. cleaning is easier than blasting off your work to start over. also make sure that when your cooking the pizzas at the same time you put them under the part so nothing drips on to the part. except pizza sticks they dont seem to drip to much.
look at it like this it needs to be so clean you will lick it. so if your not licking your part your not cleaning it enough.

[joeofalltrades]

So do you have to clean the carb cleaner off or does it disipate completely? If you clean it, what with?

Joe

[tinbender722]

Seems to me that I've had more problems with outgassing lately - I blame it on my wifes cooking - She says I've had the problem for a while.

Leo

[KZjim]

ohh damn.. pizzas BELOW the parts.. ok.. i get it..

carb cleaner... hmmm ill give it a try...


thanks for the tips guys!

jim

[11111111]

no it evaporates very fast