terra sig vs. slip

[preeta]

Lately when I have been looking at pots online, i notice a lot of people using terra sig. instead of slip. not the traditional use of terra sig., but using it like a slip. they are mixing mason stains and getting bright colours with terra sig, not for clay inlay. 

i have to wait for school to start in two months time before i can test the difference.  

wondering if any of you have experimented with terra sig to cover a darker clay body or even just to add colour. i am curious why someone would choose terra sig. since its so much work to make. as compared to slip. 

[Magnolia Mud Research]

11 hours ago, preeta said:

Lately when I have been looking at pots online, i notice a lot of people using terra sig. instead of slip. not the traditional use of terra sig., but using it like a slip. they are mixing mason stains and getting bright colours with terra sig, not for clay inlay. 

…

wondering if any of you have experimented with terra sig to cover a darker clay body or even just to add colour. i am curious why someone would choose terra sig. since its so much work to make. as compared to slip. 

 
I use OM-4 terra sig on the bottoms of stoneware "pots" as a means to keeping the bottom smooth to prevent damage to the surfaces that supports the "pots" in use or in storage -- such as a vase sitting on the piano. 

The color of the bottoms with terra sig may be different than the raw clay body.   If you are routinely using the same clay body, you can mitigate the color mismatch by making the terra sig from the clay body instead of from dry clay; the yield will be lower but the color match will be closer.   

A colleague use to use Redart terra sig over white stoneware instead of black underglaze for sgraffito decorations. 

The main differences between terra sig and slip are average particle size and solids to water ratio of the slurry.   Application thickness is a variable that can become important;  I have encountered peeling of the terra sig coating during the final firing when the application was too thick on cone 10 stoneware.  For my work it was not a significant issues as the flasks were actually enhanced by the "ancient" appearance the flaking produced.   I suspect that the peeling could have been overcome by applying the terra sig at the leather hard stage rather than at the bone dry stage.  

Slip and terra sig are analogs to buttermilk and skimmed milk.  They do not look or taste alike but both are solids suspended in an water.  

 
Milk has always been a beverage, but some folks have made a living using milk for painting chairs and kitchen tables and cupboards. 
 
By the same analogy,  you can find non-traditional uses and application techniques for terra sig and slips.  
 
I have used Redart (and also local clay) slips and terra sig on white and buff stoneware to produce contrasts;  Redart terra sig over (and under) glazes to make contrasting marks on/in the glaze.  
 
Robin Hopper often recommended the "try it and see" approach.   I am fond of (from the way back) Alka-Seltzer commercial's approach to many of the studio ceramic puzzles:  "Try it; you'll like it! ...".   As Edison said: “Just because something doesn't do what you planned it to do doesn't mean it's useless.”  Pay attention to what does happen, and then think about how to use that "happening" effectively in producing your product.  

LT

 

[Callie Beller Diesel]

Greg Payce uses various terra sigs coloured with mason stains to decorate his clay work with. No glaze. It gives a soft, satiny finish to the pieces, it’s easy to apply, and yes, it can cover dark clay. In this specific instance, it applies more like commercial underglaze than slip, but has a much softer feel than either slip or underglaze once it’s fired.

(this guy was the ceramics department head at ACAD when I was there.)

 

 

[preeta]

LT i've been meaning to play with RedArt to see if it turns into glaze since its a lowfire clay.

ive played a little with oxide terra sigs when i didnt have much of an understanding of it at my previous school. but now i cant wait to get back to test.   but i do remember how buttery it was compared to the rougher slip. 

thank you for bringing up the red terra sig. i hadnt thought about red terra sig. i do want to try the ancient greek method of how they reduced and then oxidized to keep the different colours of clay as decoration.  i really like the idea of having it in certain parts of the pot to change the colour of the glaze somewhat. 

try it and see is my life's philosophy. and robin hopper was the guy who  opened my eyes to the many options available. owe much gratitude to him. 

callie i have researched Greg Payce before (not for his surfaces but for his forms).  that must have been interesting being around him. 

BTW i emailed all tlhe potters who used Terra Sig instead of slip and heard back from all of them. their answer? that's what they had around so they played with terra sig. some of them are  now trying out slip and engobes. how simple is that. i had better access to slip than terra sig and therefore i used slip. 

[Roberta12]

I was at a workshop last week and was introduced to terra sig for the first time.  The instructor uses it on bone dry clay, colored with mason stains, to add color to the underside of her work.  Her name is Adrienne Eliades and is very approachable.  Preeta, if you are interested I can send you her contact info and the TS recipe that we used.  She is also on IG and her handle is @bugaboo_eyes.  You can check out her feed to see her colors.  We were using bright mason stained TS.  Some people burnished and some did not.  It can add another dimension to your work.  

She said that she uses red art ts on lowfire clay.  Not sure if it has other uses as well.

Roberta

[preeta]

oh thanks Roberta. I'll contact Adrienne on IG. I have a base white ts but i dont have mason stain recipes. ooh i am so excited. i just IGed another potter who has tried both, and he said he uses TS so he does not glaze the outside of his mugs. he lightly burnishes. i am going to try that myself. 

in a couple of weeks i am going to make some RedArt TS. and see if it turns shiny.  or what happens. 

i saw another artist who uses pastel colours stretch her underglazes with TS. hmmm!!!

 

 

[Roberta12]

2 hours ago, preeta said:

oh thanks Roberta. I'll contact Adrienne on IG. I have a base white ts but i dont have mason stain recipes. ooh i am so excited. i just IGed another potter who has tried both, and he said he uses TS so he does not glaze the outside of his mugs. he lightly burnishes. i am going to try that myself. 

in a couple of weeks i am going to make some RedArt TS. and see if it turns shiny.  or what happens. 

i saw another artist who uses pastel colours stretch her underglazes with TS. hmmm!!!

 

 

the only thing I noticed about the cups that had TS on the exterior is that the rims were not pleasant against the skin.  If I were to do that, I would dip the rim in clear or something.  I am all about the smooth! 

[preeta]

Oh yes of course.  Thanks for the heads up.  Yeah I’d glaze the rim.  

[tinbucket]

I asked my friend a very similar question recently and she prefers terra sig because it is like the pot is wearing a thin veil versus slip which is like a the pot is wearing a thick winter jacket. Covering a pot with slip removes some of the marks made by the maker's hand. I have been experimenting with terra sig and although I know it is not the traditional use, I have been very happy with Redart sig at cone 6. It doesn't completely melt and is not 100% water tight, but on the outside of a pot is a beautiful deep red with a slight shine. 

[Marcia Selsor]

Terra sig, if applied too thick, can pop off the surface. I find it odd that people are using it as a slip. Maybe their sig has an added ingratiate to overcome the flaking problem. 

Marcia