[cracked pot]

I have coated the inside of a bisque fired mug with Suze's Black Slip and would like to leave the outside natural with clear glaze over all. This is a Cone 6 white clay. The problem is that there is yellow staining on the outside of the mug from the black slip. My question is, will the yellow stain burn off in firing or should I use white underglaze too keep the outside of the mug white? I got the recipe for the slip at a workshop and have not worked with it much yet.
Thanks.

[neilestrick]

The yellow staining is most likely just from the water in the slip. It should burn out. Is this truly a slip, though? Slips will not adhere to bisque....

[cracked pot]

neilestrick, on 29 March 2012 - 05:12 PM, said:

The yellow staining is most likely just from the water in the slip. It should burn out. Is this truly a slip, though? Slips will not adhere to bisque....

Thanks. Some of the yellow has faded so I think you are right. The slip is mostly alberta slip clay and OM4 with chrome oxide, cobalt carbonate and red iron oxide added. Recommendations from instructor say can be used on bone dry or bisque ware but best on bisque. It's a really intense black. I've used it before on greeware and over glazes to make marks. Hope this works as well!

[scoobydoozie]

Aren't underglazes basically colored slip? It used to be taboo to apply underglaze to bisque, but we are now doing that in low fire mold cast ceramics. We have to fire again before glazing, but it adheres with no problem and doesn't crack. Keep in mind this is three brushed on coats and not extremely thick coats.

[ayjay]

neilestrick, on 29 March 2012 - 10:12 PM, said:

Slips will not adhere to bisque....

I've successfully used a 50/50 mix of kaolin and ball clay on stoneware bisque - can add oxides if required.