Friday, April 5, 2013

Hot Coating: Domes, Dishes and other oddities

So far we have shown how to powder coat flat surfaces but inevitably we want to do a dome or concave shape, we are artist after all and the world still isn't flat. So this post will be about a technique called hot coating, essentially heating the piece up and applying the powder coat. Odd shapes are coated with a static gun everyday, the benefit of charged particles and static attraction.  But then we get into the expenses of compressors and guns and we're trying to keep this as simple and minimal as possible. So hang on here we go.




Our first picture is of a dome that has been coated and then placed into the oven, but in placing it in the oven much of the coat slipped off and well one of these days we'll have to post a photo of the inside of our poor colorful oven. The dome turned out very spotty and without a nice even coat. To solve this we're going to put the pieces in the oven to heat them up and then sift powder coat over them and let it flow / melt.


Starting with a few different shapes so we can test steep sides verses shallow domes we place the 4 test subjects in the oven. Wet Black is used in this example and it cures at 400 degrees so we set the oven to the cure temp and set the timer to roughly 5 to 10 minutes, just enough to heat them up.

Once we hear the happy ding of our timer we use tweezers to move the pieces over to where were coating and place them on some screen. These are hot so don't place them on anything that can't take the heat. We take the sifter with powder coat and sprinkle the coat around the edges and working towards the center till an even coat is applied. Since these are small and easy to coat quickly we did them all at once but if your doing several or just playing around at first you can leave the extras in the oven to keep them warm while you do each piece individually.

Once a even coat is applied, we let the pieces cool so we can place them back in the oven without marring the surface with tweezers marks. Now that all the pieces are ready for the final cure we set our timer for the cure time plus a few minutes for them to heat up again and let them cure. Here's our four pieces after the oven cure is finished.

Alternative Methods;
Using a small crafter heat gun we have been able to heat the pieces quickly and apply the coat. The problems are guessing what the temp of the piece is so it is more of a trail and error process. Also you are heating up the surface below it allowing the powder coat to stick to it also. Remember a clean shop and tools make for easier work or so Amy keeps telling me.

We've also tried a small butane torch but ended up with oxidation, fire scale, on the pieces before we could coat them so torches aren't the best for this technique.

Keep your oven door closed, A&J




 

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