Cone 5 firing vs Cone 6 firing

[jothamhung]

Hi everyone,

It's been a while since I've posted, but I've recently acquired a large commission of 80 pieces for a local restaurant that I'll be making in my home studio. They wanted the pieces to be thicker and more durable through wear and tear. I've been firing consistently at cone 5 with clay and commercial glazes from Laguna. I was wondering if firing to one cone higher would be better in terms of having the pieces last longer through more wear and tear in a restaurant. It'll be more vitrified? But I'm also concerned of the possibility of bloating or issues with the glaze and clay. The kiln I have is an FX27P with a kiln sitter, I use witness cones as well. The clay body is LB-6 and the glaze is the Versa 5 White, all from Laguna. Any input would be greatly appreciated! Thank you. 

[liambesaw]

Try on a few test pieces.  Has 3% absorption at cone 5, not great

[neilestrick]

You'll have to test it to know for sure.

[Bill Kielb]

18 hours ago, liambesaw said:

Try on a few test pieces.  Has 3% absorption at cone 5, not great

+/- 1%! So really not great.

[Mark C.]

For restaurant ware a better body with less absorption would be preferred .

You can fire some test bars to cone 6 and do a absorption test to see what it is.Also test the glaze at that temp

[neilestrick]

The government requires that restaurant wares be vitrified. They don't specify an acceptable absorption rate, but 3% isn't vitrified IMO. Potter's shoot for below 2%.

[jothamhung]

Thanks so much for all the replies! I appreciate it. I've been talking with the client and they were okay with receiving the pieces despite the absorption rate and information I provided from you guys.