Fusing Holes with Chalk

I’ve gotten a number of questions about fusing with chalk to make holes, so I thought I’d give it at try and see how it goes.  I started with chalkboard and sidewalk chalk, both of these were from my local grocery store.

Fusing with Chalk

Chalk for Fusing Tests

Since I was also fusing a large batch of donuts, it seemed like the logical thing to just use those.

Fusing with Chalk

Donuts and Chalk

The thin chalk stick was easy to snap into pieces, but the sidewalk chalk is very soft and hard to break without crushing it, so I used my handy hacksaw. The chalk is also very dusty, so I wore a mask.

Fusing with chalk

Sawing up chalk

Once I had discs of chalk, I added them to the center of my donuts.  I also carefully sawed a few into shapes, just to see what would happen.  The thin chalk I put in the center of my Bombay Micro Donuts.

Fusing with Chalk

Fusing with Chalk

I decided to add one more test to the mix, since testing is where it’s at.  I painted one of the thin chalk pieces with kilnwash and left the other one uncoated, just to see what would happen.

fusing with chalk

Chalk tests

Then I fused the whole batch using my standard full fuse schedule.

Fusing with chalk

All Fused

Sadly, the heart and the star didn’t work as well as I had hoped.  The hexagon and circles worked well though.

Fusing with chalk


Here are some donuts fused without chalk for contrast.

fusing with chalk

With and Without Chalk

Now, the kiln wash test, here are the donuts after fusing.

fusing with chalk

Fused micro donuts

It does look like the chalk with the kilnwash worked a bit better.  Here are some micro donuts fused without chalk for contrast.

fusing with chalk

Microdonuts with and without chalk

Here are the things I learned from these tests:

  • Smooth sided chalk works best, some of my glass hung up on the ‘Crayola’ on the sidewalk chalk
  • Sidewalk chalk is much softer than chalkboard chalk, and easier to remove after fusing
  • Kilnwashing the chalk helps.

Other uses for chalk in bottle glass fusing:

  • Use chalk to hold the bottle neck open during fusing so you can put the cork back when it’s finished
  • Use large chalk under the bottle neck to give a slumped shape to the neck
  • Use strips of thin chalk under the bottle to make raised soap dish style areas

Other stuff:

I checked in my handy local Environmental Health and Safety expert to make sure the colors in the chalk wouldn’t turn into anything nasty when fired (it won’t).  And I vented the kiln to outside while firing.

Related products:

Ready to Fuse Bottle Glass Donuts

Swirl Donut Mold

Crosshatch Donut Mold

Related Articles:

Fused Bottle Glass Donuts and Rings

Mica Decals on Fused Glass Donuts

Leaf and Droplet Shaped Donuts