I've been working with 3 Cerdec Degussa stains. Yellow, Red and Brilliant Red (I have the numbers) and applied them at a 10% rate to test tiles. After applying a clear base (no titania) with 1% green nickel oxide I found the yellow and red totally over nucleated. And although the Brilliant Red peeks through and shows some background the stain is very weak.

After increasing the Brilliant Red to 20%, the stain is much more intense, but there is much less background showing.

I refired one of the 10% Red pieces after adding base glaze with a 2% Custer Feldspar addition. Although the background shows through now the soda spar seems to have had changed the appearance of the crystals negatively.

I recently fired three 20% Brilliant Red test pieces with 1.5% additional 3110 frit. Although more background is showing, its still not the "Cat's Meow".

Borrowing on things I think  the Wizard of Clay said, I decided to try them.....but where to start? I recall him saying (and I'm paraphrasing) "...to get fewer crystals increase the flux... decrease the zinc....decrease the silica....".

I weighed out 4 test batches. The first being my normal clear base with 1% green nickel oxide. The next three being the same except one with 5% more frit, one with 5% less zinc and the last with 5% less silica (even though my base formula at 14.4% silica doesn't have nearly as much as others I've seen).

After twice sieving them I mixed combinations of them to get various intermediate compositions, such as 2.5% more frit, 2.5% less zinc and 2.5% less silica.

What a PITA! After calcining my zinc it has more hard agglomerates and is more work to get through the sieve. I've kind of forgotten this pain since getting a Vita Mix blender which I've been using to mix glazes. No sieve....no multiple passes....no hard agglomerates. Just VROOM! Thanks again Mr. Wizard!

Anyway I applied these to test pieces and put them in the 42nd firing.

Return to Main Page

Phil Hamling

376 County Route 1

Warwick, NY, USA 10990