Hello all-
In keeping with my constant search for new and interesting things to try out, I recently did some research into chemical engraving, and have found that it's actually pretty easy and has some fairly spectacular results if you're patient and have a steady hand.
Where this ties into woodturning is in embellishment. I've often enjoyed seeing turned items that have been carved in various ways, but having done a fair bit of carving myself in the past, it's always seemed like a little too much for me to invest in a single turning- and it often seems to take a little away from nicely figured wood.
But, with far less effort, and possibly even more bang for the buck, a guy can dress up a rather plain turning with a handful of dollars and some brass or copper shim stock. (Any kind of metal will work, but I like the look of the brass the best, personally)
Thin brass shim can be cut with a regular pair of scissors (as long as they're not your wife's "good" scissors, that is...) to whatever shape you need.
So here's the proposal (and to appease Arch, I'll note that I've already done this, and it works in practice just as described)
Turn yourself some kind of object- I don't care what kind, it's your project! At some point on the turning, scrape out a shallow groove roughly the same depth as your shim stock, and the same width as your inlay. Now you've got two choices, depending on your inclinations. You can measure the diameter of the piece and multiply that by
3.1415... to get a length for your shim, or you can wrap something around the outside of the turning to get the same measurement. For this first one, make sure that the groove's bottom is parallel to the line from the headstock and tailstock- this is just for simplicity, as you will need a rectangle, rather than a curve that will form into a cone section if you keep things even.Now comes the new part- you're going to need a few things that are pretty inexpensive and easy to get, but you'll have to get them before proceeding. The first, and most difficult, is Ferric Chloride. Even though it's the "most difficult", it's not all that hard to come by. I got a quart bottle of the stuff mail order from an outfit called "Dick Blick art supplies" on line for about $4. This is used for circuit boad etching as well, so it may be availible at a place like Radio Shack, though I have not looked yet. You'll also need a "ground" which is sold as etching ground *or* a sharpie. If you use a sharpie, you'll need some plastic tape as well. Other than that, you'll need a shallow glass or plastic dish that you don't intend to use for anything else ever again, some baking soda, and something to scratch away ground.
Since I find it easier, I'm going to focus on the sharpie method. If you use the ground, you'd paint it on, and then scratch off the ground where you want the material to be etched away. Clean the piece thuroughly, and then cover everything you don't want etched away. In practice, I've found that laying tape over the entire back, and then drawing the design on the front with a sharpie is the easiest way to go. Make sure that the drawn area is filled in completely. Anything that is not covered with marker or tape will be etched away.
Once you're happy with the design, dump the ferric chloride into your pan, and stick your material into the chemical face side down, and swirl things around every so often. In about 10-15 minues, there will be a perceptable difference between the depth of the etch and the surface of the material. You can etch it as much or as little as you like- eventually, it will eat all the way through the material, if that is what you are going for.
When you're ready, pull the piece out of the chemical and sprinkle it with baking soda to neutralize it. As far as I am aware, it should now be safe to rinse under the tap without messing up your plumbing, but use your own best judgement.
Remove the tape, and wash the entire thing with acetone or alcohol. This will remove the adhesive and the sharpie. You could be done now, depending on your inclinations, but I prefer a sharper contrast. I've heard that shoe polish is good for antiquing brass, but it doesn't work that well for me, so I've been spray-painting the face with flat paint, and then hand sanding the high points of the brass with
800-2000 grit sand paper with good results.After that, you can epoxy the strip into the groove you cut in your turning, and proceed as normal. The etch is usually not all that deep, unless you let it soak for a pretty long time, so be sure not to sand it off when finishing up the piece. It's not a terrible idea to tape the brass as well, so that it does not get the same finish as the wood, and retains it's lustre and can be polished later if needed.
At any rate, it's about as easy as can be imagined, and well worth trying out if you're getting anxious to try something a little different with your turning. More information can be dug up with google searches for "intaligio etching" and "photochemical machining"
Have fun!