Pushing Slip to Engobe

[BlackDogPottery]

Hi all. Just wondering what would it take to push a clay slip to engobe? I mean just plain ol throwing clay. I was thinking of adding a little frit ( 3124) to my slip but I'm not sure how much would be a good starting point. I have tried previously with Gerstely Borate but it bloated horrible. Would a 50/50 mix of frit and clay likely end with bubbles? I was hoping to come up with something that just melted enough to smooth out the brush strokes at ^6.

Thanks! 

[Ceallach]

The studio that I am in has a standard ^10 slip recipe that they use (with it seems like ALLTHECLAYS.).  I am doing work with white slip over black clay, sgraffito/carving, and then doing a wash of temmoku which amps up the iron in the clay.   Take a look at my profile for a better idea.  

As part of experimenting with slips, I tested that slip with varying amounts of Frit 3124 for a better finish on the slipped but unglazed areas in a line blend from 11 to 22%.  As it goes from 11 to 22% the fully fired slip gets a bit grayer, and vitrifies a little bit.  I settled on 22%, but may back that down for more white.   It vitrified as early as 15%, but YMMV.

So 22% worked for me, but I am not glazing over it.  I had an anomaly on the last firing, and recommend testing this through to glazing with your glazes and clay. 

[BlackDogPottery]

Thanks for some input. So that's at ^10 right? I'd imagine it would only take a few more % to lower it to ^6. 

By the way if you are looking for a vitrified matte black to sgraffito, I have a thread started under "Red Clay" that I log in trials of different portions dark stoneware and Manganese slip. It works well for that kind of stuff. The reason I was looking for something else was I honestly couldn't bring myself to sell domestic/usable pottery to people that contained so much Manganese.

[Min]

On 3/9/2018 at 7:07 PM, BlackDogPottery said:

I was hoping to come up with something that just melted enough to smooth out the brush strokes at ^6.

Have you tried adding a tiny bit of darvan to your slip to make it more fluid so the brush marks level out when brushing?

[BlackDogPottery]

On 3/24/2018 at 8:45 AM, Min said:

Have you tried adding a tiny bit of darvan to your slip to make it more fluid so the brush marks level out when brushing?

No, but I have been experimenting with some Xanthan Gum I found which oddly acts like it I think. It keeps stuff suspended and (I found this out after making this thread) makes it lay down way more smoothly. It's pretty handy stuff.