Dark brown clay slip on white stoneware?

[KristynZ]

This might be a dumb question, but I'd like to sliptrail Standard 266 (dark brown) over Standard 240 (white stoneware).  I'm assuming this will work? I want the natural look of the brown clay to decorate with instead of an underglaze. I know I can just do test tiles but I thought I'd ask here to see if anyone has done this.  Thanks!

[Callie Beller Diesel]

I tend to work the other direction: white clay over red, and I used a different brand. I’d start by checking the shrinkage rates of those 2 clays against each other, and make sure they’re pretty close. Pay special attention to the wet to dry rate, as well as the final fired results. You want them to shrink together as much as possible.

[Magnolia Mud Research]

3 hours ago, KristynZ said:

I'd like to sliptrail Standard 266 (dark brown) over Standard 240 (white stoneware).  I'm assuming this will work? I want the natural look of the brown clay to decorate with instead of an underglaze. I know I can just do test tiles but I thought I'd ask here to see if anyone has done this

I have not used either of the two clay bodies you mentioned, but I often use a different clay body as a "slip" or "paste" on the exterior coating of the main clay body of an object; the technique is usually done at just before setting the object aside to dry, but can be applied at almost any stage.  Slips have significant more water than the surface being covered may lead to cracking of the slipped marks.  

Practice generally solves that problem.  I recommend trying on simple forms and develop your method of application and timing on the forms you make.  

LT

[Pres]

@KristynZ I know that the 266 is a ^5 clay with 12.5% shrinkage rate, the 240 which I have used in the past is 13% shrinkage rate at ^6. You would have to fire the 240 to ^5 I would think. However, to best know what is going on test tiles are appropriate. I think you will find that the 266 may turn glossy and act a a glaze, or it may bubble at ^6 from boiling. Only testing will tell. Shrinkage rates at ^5 are very similar so should  not be a problem.

I have used the 211 Hazelnut over the 633 and vice versa with no problem. However, these are not as contrasting as the choice you have mentioned.

 

best,

Pres 

[Hulk]

I'm still using Aardvark red stoneware slip ("SRF" - a cone 5 red) over several other cone 5/6 stoneware bodies (buff, white, off white) without issue (lucky, aye), having made up several quarts a few years ago.

Am responding here to offer this: after whizzing bits of clay with water to the desired consistency, consider running it through a screen to remove sand/particles - brushes nicer afterward. 

[oldlady]

to practically guarantee success, just use the white clay alone.  no worries about fit.  make slip with the white clay.  color it with red iron oxide to a dark brown.  brush or dip or spray or apply with ear syringe the slip onto the white pot.  do this as soon after making the pot as possible, before the pot begins to dry.

if the brown clay is so dramatically different from the white slip with ROI, add some cobalt to the slip to darken it.