Finish Work on Metal Art: After Sandblasting
The Voice: Hey, Kevin. What are you doing?
Kevin Caron: Did your mom ever yell at you for writing on the walls with a Magic Marker? I can do it for fun now!
This is Perchering, one of the large metal bells I created in my studio. It just came back from sand blasting, so now all my little boo-boos, all the little bits of porosity or the little crack in the metal that I missed while TIG welding, or may have ground too far, all my little mistakes show up.
Now I come back with a marker and mark them all, take the piece back to the workbench, grind it out, clean it, re-weld it, patch it, do whatever I have to fix that little mistake, and then it's ready to get a finish on it. As you can see, I've got a few of them to take care of.
Some of them I may just be able to grind out real quickly. But, when it comes to the porosity, I've got to grind it all out, take it back down to good metal, or just take that whole chunk of metal out and replace it.
Here's one of the seams where a piece of metal got welded in, and you can see the little bubbles and holes. That was either where I didn't have the metal clean enough before welding and a dust got into it, or a gust of wind came through and blew the gas away from the weld, so it got a little bubble. Now I have to put on my welding helmet, come back in with my grinder and clean those out.
This tool is an abrasion wheel; sometimes while working on a bubble the wheel wears away and then dust gets mixed in, along with the metal shavings. We blow out the dust and shavings using the air gun. Next I come back with the welder and weld it shut.
Remember, you can't just weld right over the holes, because the bubble is still down in there. If you try to weld over the top of it, the bubble inside will become super-heated in the weld (the air that?s in that little cavity) and bubble right up through the weld and pop again.
Even if you just grind a little bit of the bubble away, that's not enough. You've got to get all the way down and either find metal, or go all the way back through again to get rid of that air bubble. Once you take it all out, then you can go back and weld it. If you try to cover it up, it won?t work.
As you can see on one of the sound sculptures I'm working on, there's a little spot right on the top. This is why it failed its pressure test: it had a little pit in it. When you sandblast it, the pits come out even further. I've got to grind that out, fix it, and then weld a little more on top so I can smooth out my weld.
I used to sit here with a big grinder and grind all the paint off with this smaller power tool. Well, it would take three or four sanding pads and about two or three hours to clean it. With a big sandblaster, it takes about 10 minutes. I've got to get one of those power tools someday.
I've got to go back to work. Bye.
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