Kiln wash won't stick to new ceramic mold

[LDGlass]

This is the first time I've encountered this problem. I was putting kiln wash on some new molds tonight. One of the molds the kiln wash beads up. These are ceramic molds like all the rest that I have. I mean it kinda sticks but I can brush it off in areas. It's like there's something on the mold yet I can't see or feel anything. What is the problem? Help help.

[Peter Angel]

There might be some oil or residue on the mold.

Perhaps firing it in your kiln to a low temp might burn the oil off? Washing it with soap and water might work as well.

[rosanna gusler]

i would fire it to 1000f or just put it in with whatever firing you do next. if that does not help then what you have is a result of how the mold was poured. the clay can be compressed in an area and less able to easily hold kw.

[Morganica]

If it's still doing that after firing you can sometimes fix it by sanding the area. I use a coarser grade of sandpaper and bear down a bit. That gives the area a little tooth so the kilnwash can adhere. Doesn't always work, but it's worth a try. Any marks you make on the mold will be filled in with kilnwash, so it doesn't affect the texture.

[LDGlass]

Thanks for the suggestions. I will give them a try!

[Laurie Spray]

When they make molds with a "pour slip" method….where the slip hits is called a hard spot. It usually may look like it does not have kiln wash on it but it probably has some. I would lightly sand it or put it on a hot kiln, try again, and then use it!