welding question
- Thread starter akitagandy
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rooster57 said:
Rooster,
I've read that Lab Metal is the best stuff for filling imperfections before powder coating as well. But, I've also read that you need to cook/out-gas the part for a while before you apply the powder. If my memory is correct, the part is put into the oven and held at 500 degrees for about an hour, than let cooled down to about 200 degrees, the powder is applied, then back to the oven to cure the coating.
The same sometimes goes for powder coating castings like intake manifolds and wheels. Castings will out-gas a lot, so pre-cooking them is important. Some castings out-gas a lot from just the little cavities they have inside, that if you cool them back down before applying the powder, when the casting is re-heated, the simple expansion of the gases in the casting will ruin the finish. Some castings need to be brought up to full temp for a while, then the powder is quickly applied with the part at almost curing temp, and then put back into the oven to cure.
I remember reading all this somewhere when I was doing my research to powder coat in my little space.
David
I have done a little bit of powder coating here at the shop. In a kitchen oven you can put a lot of car parts. Valve covers, intake manifolds, Steering boxes, etc. Out gassing is a real problem on castings. It was such a problem I quit doing it, more trouble than it was worth on such a small scale. A kitchen oven does not get hot enough to really out gas these parts. I have some good friends that do this every day for a living so I just let them do it.
They cook eveything for several hours at 600 or higher to start with. Then it is sandblasted. Cooked again at 600 or higher for several more hours. Sandblasted one last time and powder coated. After the last blasting they don't touch the part with their hands. They have dedicated gloves to use so no oil from your skin is transfered.
They mostly do ceramic on headers. They told me when they first started in business they were leaving finger prints in the ceramic. The only way to get rid of it was to start all over.
The only problem with powder coating is you cannot touch it up as you can with paint. You get a scratch on your powder coated frame and you have to take the whole car apart, sand blast the frame and redo the whole thing.
They cook eveything for several hours at 600 or higher to start with. Then it is sandblasted. Cooked again at 600 or higher for several more hours. Sandblasted one last time and powder coated. After the last blasting they don't touch the part with their hands. They have dedicated gloves to use so no oil from your skin is transfered.
They mostly do ceramic on headers. They told me when they first started in business they were leaving finger prints in the ceramic. The only way to get rid of it was to start all over.
The only problem with powder coating is you cannot touch it up as you can with paint. You get a scratch on your powder coated frame and you have to take the whole car apart, sand blast the frame and redo the whole thing.
rooster57
Member
I think lab-metals problem is the burnoff stage. The orig lab metal has a max temp of well here is the clip of the spec artical.
Lab-metal is aluminum filled, resisting attack of rust, rot and mildew. Lab-metal withstands temperatures as high as 350F (and as low as -40oF) and when hard, can be painted with lacquer or enamel without danger of bubbling, lifting paint, chipping or peeling. Lab-metal stands up to normal paint baking procedures and may also be powder coated (see special powder coating instructions).
So it seems to me the materal would need to be applied after the burnoff stage. Their is a local company that is using what they call inviro-coating that is earth friendly and only requires a 200 deg temp to set the powder. I have seen some of their finished products and they look good.
Lab-metal is aluminum filled, resisting attack of rust, rot and mildew. Lab-metal withstands temperatures as high as 350F (and as low as -40oF) and when hard, can be painted with lacquer or enamel without danger of bubbling, lifting paint, chipping or peeling. Lab-metal stands up to normal paint baking procedures and may also be powder coated (see special powder coating instructions).
So it seems to me the materal would need to be applied after the burnoff stage. Their is a local company that is using what they call inviro-coating that is earth friendly and only requires a 200 deg temp to set the powder. I have seen some of their finished products and they look good.
rooster57
Member
As far as powder coating over existing PC my guy says they do it all the time big ole part comes out of the oven and has a spot they missed they put the ground strap back on it and powder it and back in the oven it goes. now granted it just came out of the oven maby that is the dif dont know. His is 40 feet long and 16 feet high and 20 feet wide. he does a lot of big stuff.
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