Thought I would share my experiments on transferring images onto washers. This method works pretty good.
tee-shirt transfer paper
oven or toaster oven
Print some images onto your transfer paper, (I prepared my images in photoshop)
Cut out the images and iron them onto your washers, be cautious as the paper my slip, you need to really hold it down and check occasionally, very carefully, to make sure the image is adhered to the washer.
Once it is adhered remove the paper. Now take the washer and stick it in the toaster oven for a while (350) check it to make sure the image does not burn too much. once cooked it is very hard to get the image off I even tried scraping it with nail and it did not scratch it at all.
The washers that look copper they came out that way because i left it in the oven too long and it burned a tiny bit, but I liked the look. If you are going to try to get that effect you have to watch it very carefully, too long it will just turn all brown and the image will disappear.
here is some copper piping I transferred an image onto, it was harder because of the roundness of the pipe. I taped the image at the seam onto the pipe to iron it on.
enjoy and please show us your transfers if you do any. I have not done any in color, but I bet that would look cool.