Chefspence wrote:Oh man that sounds fun. I'm gonna have to try it! I have actually printed a few t shirts of my own before with transfer paper. Is it like that or am I off base here?
It's very similar.
(Disclaimer: I have yet to use this method personally. I'm currently playing around with the acid wash process using nail polish as the resist and plan to build a little power supply to do some electrochemical etching. I learned of this method after finding out toner was a thermoplastic and then a subsequent search found that this method was being used in jewelry.)
Most professional fabric transfers use a form of thermoplastic polymer called poly(vinyl chloride) aka PVC, printed on a substrate (the transfer paper) that provides for a weak bonding. You probably think of plumbing pipe when you hear PVC, but it comes in many forms, rigid and flexible. When heated, the plasticity- ability to change shape- of PVC increases and allows it to mold to any surface it's pressed into. When heated and pressed into fabric, the PVC clings easily to the much higher surface area of the fabric and as it cools and the substrate is peeled off, the PVC sticks to the fabric more than the paper.
Laser toner also uses a type of thermoplastic, often PVC, as a matrix to hold the pigment powders (carbon powder for black). It's a slightly different process: a laser changes the electrostatic charge on a drum that picks up toner in the pattern the laser draws, and presses it onto the paper. The paper then runs through a heating roller or under a heating element to melt the polymer matrix and semi-fuse it to the paper. It's actually similar to powder coating, where the electrostatically charged polymer powder particles are attracted to the oppositely charged item being coated, and then the plastic powder is "set" inside a low temperature oven. \tangent
For making the resist, start with printing on transfer paper or transparency film like you would for fabrics. Fully degrease the steel surface with denatured alcohol and apply the transfer with a clothes iron. Hopefully the PVC clings to the steel more than the substrate when you peel it away after a short cool. You might have to try this a few times to get it to stick well enough.
Since PVC is virtually immune to acid, it will resist the acid and protect the metal underneath. After the soak in acid, you can heat it up a little again and scrape it off with a non-marring material. Acid soak times will depend on the strength of acid solution you use, which you'll have to experiment with. When you pull the blade, neutralize the acid left on the surface in an alkaline baking soda water solution or with liquid ammonia (Windex is 5% ammonia).
**Important note: The more powerful the acid, the shorter the soak times, but the more dangerous to handle and store.**
***Most thermoplastics become flexible enough to "melt" at around 300-325°F. In theory, this should be low enough to not mess with most steels' temper if applied for a few seconds to a couple minutes or less, but I make no guarantee of this. If the heat transfer method worries you, you could make cutout stencils to use for painting a lacquer (nail polish) on the surface in a pattern.