Molten glass is very sticky. Unless we as glass makers put something in between the glass and the kiln shelf, the glass will stick to it. Once it is cool there will be no way to separate the glass from the shelf without damaging both the glass piece and the shelf.
We need to coat the shelf with something to prevent that happening. Kiln wash is ideal for this purpose. You could also use thinfire paper or papyrus paper but these are not as cost effective. I use Bullseye Shelf Primer for my shelves but there are many other makes you can choose from, Shelf Primer is easy to use and I’ve made a little video to show you how.
Some important things to note about the video.
It is really important from a safety point of view to wear a mask whilst working with shelf primer. It can irritate the lungs so a mask is essential.
A haik brush is best for applying the shelf primer as it has very fine bristles. You could use a paintbrush with fine bristles instead if you can’t get hold of a paintbrush.
Bullseye recommends mixing one part shelf primer with five parts of water and mixing thoroughly. Leave to slake (absorb the water) for a few minutes before using.
All kiln washes tend to settle out so stirring before each brush stroke is necessary.
Once you dip the brush in, you can touch it to the side of the bowl to remove any excess.
When applying, use long straight strokes and make sure to cover every part of the shelf in the same direction. Once the water has absorbed, you can add another layer. It doesn’t need to completely dry out, just absorb and be less soggy wet on the surface.
Each coat should be applied in a different direction so the lines created by the brush can be smoothed out with each successive layer. Once the shelf primer is dry, any marks or lines will be visible in the glass you put on top of it.
Make sure the shelf is completely dry before you use it. If it isn’t dry bubbles can form in your glass as the moisture evaporates from the shelf and gets trapped under it. You can heat your kiln shelf in the kiln for 20 mins at 500 degrees Celsius or you can leave it overnight to dry in a warm place.
That’s about it for kiln washing shelves! If you’d like to download a step by step tutorial for this post you can find it in our resource library. It’s free and all you have to do is sign up for our emails. You can do that in the sidebar or click the link here.
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