laser engraving stainless steel w/ plaster

So Bryan and I tried the airbrush and the plaster of paris particle size was too large to go through the air brush even after considerable thinning. I finally tried the solution with a cheap detail gun and it worked great. Bryan applied one coat and then used the heat gun to dry the piece rapidly. Then he applied a second coat and repeated the heat application with the heat gun. The resulting surface was quite even. We set up the Rhino file and finalized our settings using the afore mentioned settings. It worked like a charm! Check it out.

I believe this is working due to the chromium content of the stainless steel. Stainless has a passivation layer that is thin and completely transparent; Chromium oxide. When combined with calcium sulfate (plaster) along with the heat from the laser and potential water from the surrounding air, you end up with calcium oxide and chromium sulfate. Chromium sulfate creates the mark and the calcium oxide washes off. Again this is my basic premise and understanding of what’s occurring here. 

 If you slow the laser down, it will create a darker etch/mark. Higher wattage lasers should be able to reduce the power a bit from my 100% power setting on the Epilog Zing 40 watt.

cermark alternative

Bryan came in to visit me at the studio today. He was asking about the material that Eric used to engrave the flask I have. He wondered if I might have some Cermark that he could use for laser etching a stainless steel Christmas gift. He mentioned that he had heard of a DIY solution so we did a quick search and ended up with Mother's Chrome Polish and plaster of paris. As we read a bit deeper into the forum, the solution was simplified by isopropyl alcohol and plaster of paris. Bryan ran to the art store and I pulled some scrap stainless steel. We mixed up the mixture into a ketchup like consistency and then brushed it on the metal. We figured the lumpy application would give us a good test to see what the optimum thickness should be. I dried the paste like mixture with a heat gun to prepare the metal sheet for laser engraving. I made a quick hatch in Rhino and set the file for cutting on the Epilog. I placed the stainless steel in the Zing, set the setting to 100% power and 5% speed. Much to our surprise, the laser started to engrave the stainless. We pulled the piece out and Bryan rinsed the plaster of paris off. The marks remained and there is a noticeable "bite" to the engraving. You can see where the plaster of paris was a bit lumpy and the engraved image is not as dark. The results would obviously be better via spray application (air brush or detail gun) of the plaster of paris and alcohol. We are testing this now and I will report back. Regardless this sure beats an expensive can of Cermark.