How I Make Glaze Test Tiles

[Erik Evans]

I must admit, I've never been terribly disciplined about my test tiles through the years.  I'm pretty good about taking careful notes; too many times I've been burned by shoddy notes.  However, I do tend to slap those careful tests on whatever's laying around.  The result is a box full of well-documented, mismatched shapes and shards.

I finally got sick of the mess.  It prompted me to search for a standardized test tile.  Many options were considered: wheel-thrown, slab-built, pinched, and free-formed.  Eventually, I settled on an extruded tube, a variation on something I saw Bill Van Guilder using.  

These tubes are uniform, stable, strong, and provide for a lot of information in a relatively small space.  They look great in a box or hanging on the wall, and they feel good to the touch.  That's my favorite part.  About the only thing they don't do is replicate a thrown surface.  I figure I can live without that.  After nine months of using them, I can tell you the time and effort it takes to produce these things ahead of time is well worth it.  It reminds me: if something is worth doing, it's worth doing it right.  ∆

[Norm Stuart]

As you can see in Insight-Live most of our test tiles are made of scraps from my husband hand-building.

I've always liked to have the glaze showing the bottom 1/3 with one-dip, two-dips in the middle and three-dips on the top so people can see variation and especially how much the glaze runs  - pretty obvious if the demarcation between dips is not obvious.

I write on the bottom with iron oxide mixed with propylene glycol, which is wiped-out if a glaze runs too much.

When I've extruded tube test-tiles before, as I cut each segment off I smack it end-down on the table so that end has enough flat surface area to provide a stable base.

But in the end, photos of test tiles last far longer than the test tiles themselves. I just takes someone to drop it and there's roughly a 50% chance it's in pieces.

I've been having fun adding 5% alumina hydrate to glazes which run, typically bringing the Silica to Alumina ratio down to 4:1 ending up with the same glaze, slightly more matte but definitely better behaved not moving past where I place it.