glaze test tiles (can I use both front and back side?)

[s6x]

to maximize the number of tests a test tile provides is it ok to test glazes both on the front and the back of standing tiles?   or will the chemistry go through the clay and interfere with the other side?  

I read an instance where a glaze should not be used on a pot if that pot was glazed on the inside as well.?  is this a common issue or just a rare occurrence specific to one particular type of glaze?  

[Bill Kielb]

Yes, mostly ought to be fine. One color can influence another a bit I suppose on occasion but folks use liner glazes different than their exterior glaze all the time. Folks often dip their tiles … 3 second, 5 second dip …. 1 coat, 2 coats. So using test tiles and brush applying each side has its drawbacks.

With respect to glazing the outside and not the inside or Vice versa this can create an unbalanced stress in the clay as the glaze often squeezes the clay so to speak. This tiny bit of compression can increase the strength of the ware significantly. So one side glazed and the other not can cause unequal stress in the ware. End result - more fragile ware occasionally breaking suddenly when someone puts hot coffee in a cold mug for instance. Fully glazed well matched - glaze and clay- generally enhances the durability of the ware.

[PeterH]

16 hours ago, s6x said:

I read an instance where a glaze should not be used on a pot if that pot was glazed on the inside as well.?

I haven't seen that, and would be interested if you have a ref.

But I have seen occasional references to needing to let the pot dry sufficiently between glazing one surface and the other.

... this seems to be more of an issue with dipped glazes than painted ones.

[Hulk]

"...Is it ok to test glazes both on the front and the back of standing tiles?"

Good question!
My first thought was - it makes for the tests to mimic the intended applications - then, huh! ...ok, I'm going to think about that a while*...

You might try side by side comparisons, set of tiles with glaze on one side only, another set with different glazes on both sides?
It's possible that glazes that have dissolved materials could influence the other side...

I liner glaze almost everything but have never set up test tiles with liner on one side and "outside" glaze on the other side; just dipping about halfway in at a forty-five degree angle, where second dip overlaps in the middle as Bill alluded to.

My test tiles check a new glaze against clays I'm using, else glazes I'm using against new clay, looking for:
   fit - no crazing or shivering
   coverage - no crawling
   color
   fizzing/bubbles
   pinholes
   how it works applied thinly, thickly
   ...

*I pour in and out the ware interiors, and dip the exterior, with a full dry in between.
So, my test tiles don't reflect how I'm glazing wares, with liner on one side and color on the other.
When I do a set of test tiles, almost always I'll also fire a small ware or two of the test case(s) that are liner glazed.

 

Edited May 5 by Hulk
specificity

[Pres]

Great question, and as you see, there are reasons for different answers.  I dip all of my test tiles, so the are the same on both sides. Then I use small shot glass type testers to see if the glazes interact with each other in weird ways. . . . why the shot glasses?  Easy to throw off the hump, simulate a pot form and allows me to test inside and outside combinations. Finally if there are any weird interactions from different glazes that may cause the pot to crack, craze, shever or anything else, the shot glass shape is more stable and will keep the glaze from doing too much to the kiln. Lots of them can be fired as extras in any load.

 

best,

Pres