Amaco dip/brush glaze compatibility issue ... help!!

[GiselleNo5]

On 10/6/2017 at 9:25 PM, Roberta12 said:

Is Obsidian a satin/matte glaze?  Is the PC you are using a satin/matte also?  Just wondering.

Roberta

Obsidian is glossy as well as the PC glazes I'm using. 

 

[GiselleNo5]

On 10/5/2017 at 11:40 AM, neilestrick said:

When you add gum to a glaze, it holds more water. So if you add gum and then thin it down to dip, you'll be dipping into a glaze that has more water than a typical glaze. So if you normally dip for say a 6 count, that glaze with gum dipped for the same count won't give you the same thickness of application. So you'll have to either dip longer, assuming the pot is thick enough to take in that much water, or you'll have to dip more than once. That may work fine for the first dip, but it's not so great if you're doing it as a second dip like you are , because the pot will already be somewhat wet from the first dip, and if you let it dry completely before doing the second dip, adding that much water to the first dip will mess it up. You may be able to find a happy medium, but I think it will be imperfect and a lot of hassle even if you do get it to work.

Have you tried a different black glaze?

The other issue I'm having is that the glaze is literally powdering off anywhere you touch it. It is not clinging properly to the bisque. So I kind of feel that the addition of at least a small amount of brushing gum would actually solve that problem. I'm to the point where I'm having to hairspray the pieces just so they don't contaminate everything else I'm firing in that load. 

I have tried some other black glazes but I haven't liked any of them. The Obsidian is a really nice glaze, it does not move at all, fires reliably, has a beautiful smooth gloss to it when fired, and layers well with the PC glazes. I would really like to find a way to make it work without having to be brushed. 

 

[Babs]

if it comes thickish in comparison to dipping glazez, you could test ading Darvan or sodium silicate to it to thin it without adding more water.

this would reduce the shrinkage on the pot.

sodium silicate added to porcelain slip gives it a harder" surface when it dries imo

[neilestrick]

Seems like Obsidian never should have been made available as a dipping formula. It sounds like it's way to low in clay to be acceptable for dipping. You could try adding 2-3% bentonite to the dry mix. It would give it more durability, but shouldn't be enough to alter the look. A small amount of gum would help with durability, but you'd still be dealing with the added water issue.