Tuesday, December 29, 2009

Working with Metal, and Forcing Patinas on Steel

You'll remember from last week's post that the doors for the walnut media center are going to be metal. I had a metal fabricator near my shop make these for me because I saw some holes punched in a roll cage he'd made.

Like this:
These doors cost me $30 each and are 21" x 24". I was really surprised at how inexpensive they were. Strolling into a dark oily shop with welders blazing and grinders screaming may seem a little intimidating, but the guy told me himself that he grows weary of working on trucks all day and likes to something different every once in a while. The holes were cut out by his plasma cutter, then he uses a press to add the dimples. I only mention this because the plasma cutter runs off of cad files, so if you are handy with that sort of thing, or know someone who is, you can get ANY shape you want cut out for not much money. He showed me some house numbers made from 5/8" thick steel that looked terrific, but maybe you are into birds and want a life sized flamingo made of metal. No problem! Get some pink paint you'll be set. For inspiration and some inexpensive scrap, visit: http://www.industrialmetalsupply.com/ or something like it in your area.

Naturally, the doors come in a silvery steel color (this isn't stainless, by the way), but I am looking for something a little grungier and more weathered looking. I have seen old industrial parts and there is a certain character they have from use. This is what I was going for, but I refused to paint them. Paint is too thick, and to me looks like you are trying too hard to add age. There is some info out there on the web regarding patinas on steel but not much, mostly you'll find sculptors talking about aging bronze and working with copper.

From what I could find, the easiest D.I.Y. route to a darker look to my doors was using gun blue. The gun blue can be bought at most sporting good stores, but here is a link to the brand I bought: Birchwood Casey, and another link that taught me how to use it. The actual results are more black, with a hint of blue. It's easy to apply, but difficult to apply evenly. On large pieces like these, I'm not sure if I could ever get it to a perfectly solid looking black color. If you want to have a go yourself, don't forget the latex gloves and a well ventilated area! This stuff stinks something fierce, and I vaguely remember reading the word "poison" on the bottle. I tend not to get bogged down by such minor details and neither should you. Just have fun and try not to drink any of it.

Here is a door with one application (on the left):
Here is the first test door: This is full strengh applied in two coats. Sanding with 400 grit paper after the first application helped the color even out, but as you can see, it is still quite streaky.

Here is a big mess: This was just for fun. I added mineral spirits to prevent the chemical from fully getting into the metal, and just smeared it around in three or four applications. Interesting, but not for me. Note the rust on the right. This stuff oxidizes the metal in minutes--it wasn't there when I started.

Here is one I'm almost happy with: This is one application of gun blue, then sanded with 400 grit to remove most of the patina, and a final coat (two or three is better) of an oil based polyurethane to prevent any oxidation. I think what it needs is much finer sandpaper, or steel wool. Something like 2000 grit will make all the obvious sanding, much less...obvious.



Another, certainly greener, method of getting some color on steel is to burn oil into it. I used a plumbers torch to heat the metal dowel below, then rubbed a paper towel soaked in olive oil on it. I did it twice. The metal must be really hot for this to work, and make sure there is something quite thick between your sensitive skin and the nearly red-hot work piece! As you can see in the picture the metal is quite dark. But what you can't see in the pic, is that in my opinion, this gave a better result than the gun blue. It looks truly and properly old.

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