I am pretty sure that every glass fuser has on occasion had the problem of having kiln shelf primer stuck to the bottom of a piece. Fortunately, with some experience under my belt, this now happens less often. Some of the things I have learned that help avoid this problem are:
– Don’t fuse at too high of a temperature.
– Don’t hold for longer than necessary.
– Remove old primer from the shelf, prime well and make sure the shelf is dry.
– I never use the same primed shelf for more than 2 firings.
When it does happen, however, it is very frustrating. I have googled and surfed the web and tried just about every solution out there. The only one I haven’t tried is sand blasting because I don’t have the equipment. I have scrubbed baked on primer with brushes, scouring pads, and magic erasers. I have used vinegar, CLR, bathroom cleaner, and pretty much every cleaner and chemical I have. None of these worked! So when I saw a product called Wash Away that claimed to easily removes baked-on shelf primer from the bottom of fused projects, I had to try it. Many of the websites that sell this product say, “Apply without dilution to the baked on primer and then lightly scrub with a plastic scouring pad. This should remove even the most stubbornly adhered primer.” Well…. as my children used to say, “Not so much.”
Recently I had two fused pieces that had “baked on primer.” I poured some of the Wash Away onto my piece and let it sit for 5 minutes. I then used a green scouring pad to scrub it. I can tell you that “lightly” scrubbing it didn’t work. I put on more of the Wash Away and scrubbed harder. As you can see in the picture, it did take off the white primer. But, it left the glass hazy where the baked on primer was. When I fired this piece again it did go away. This technique did not work at all for my other piece. I even soaked the whole piece in the Wash Away for 10 minutes and then scrubbed. No luck.
I have tried using Wash Away to remove kiln shelf primer several times now. My conclusion is that Wash Away will work on lightly baked on shelf primer. But for most of my pieces, it did not work. The bottle did not list what the ingredient is. I wondered whether it the same thing as CLR. It is very caustic. You definitely want to wear rubber gloves when using this product. In the end, I used my diamond pad hand sanders to sand down the glass to a mat finish and then did a flip and fire. Yes! This took forever! So, the best solution to this problem is to avoid the problem in the first place!
Feel free to share any tips or trick you have that have worked for you.