Porcelain decorating slip

[Discus]

I am new to ceramics and can't seem to find any info on creating a strong white slip for decoration, not casting.Porcelain clay , I guess would be the optimum. If so how please? Powder ?...dried clay rewetted? Plus any additions? How would this work as far as compatability goes with stoneware clays? Also I would like to make an engobe white to use on bisque...any ideas please ?

[Sorcery]

Simon Leach uses a Porcelain/Custer mix for Hakeme. I tried to imitate it using 76g Standard 130 cone 10 and 24g Custer, it flakes off at cone 6 when thick, and thin it stays, but Dusty.

So don't try that!

Sorce

[Discus]

Thanks...definitely not what I need!.Looked at his video just yesterday ,which got me thinking and searching.Thanks for the warning.

[Hulk]

Hi Discus!

I'm using red and white slips on mid fire (cone 5/6) stoneware; am blunging up clay (Aardvark Clay SRF, red, and BMix, white) in a blender (add small bits!), aiming for a consistency that just turns in the blender, then running through a sieve. Both seem to work well; I'm applying after the piece has been trimmed. They both burn away somewhat in the glaze fire; had hopes for black slip, however, it comes out brown and causes problems.

[Discus]

Hi Hulk, Thanks for info...learning more by the hour...looked up Bmix and unfortunately doesn't fit the bill for me as it is described as a creamy white and I am looking for a pure as possible white. Will bear in mind mixing technique you use.

[Roberta12]

@DiscusI call this first recipe Porcelain slip.  It was given to me by an art center where I had taken a class.  They take it all the way to cone 10, gas, but assured me it could be used at midfire.  I have tested it on porcelain, speckled stoneware, and dark brown stoneware. Cone 6. Electric.   It is very white.  I don't think it is a slip in the traditional sense, but I use it to create a white background on brown clay.  The glaze people on this forum can tell us why it works as well as it does, or what their concerns would be.    I use it rather on the thin side.   I can put underglaze transfers over it, rice paper decals, or carve through it. Then I put a clear glaze over it.   Maybe it is not what you are looking for, but here it is (this is how the recipe was given to me, in % and cups)  You can also color it with mason stain. I have used this recipe on  both greenware and bisque.  It cracks a little on bisque (because of shrinkage, I suppose) 

Porcelain Slip

EPK  50%                    3.5 cups

Silica 24%                  1 cup

Potash Feldspar (custer) 26%   1.25 cups

This is another recipe that I received from Naomi Clement. She wants a very white slip.  If you look at her work on Instagram, any of the white décor is this slip recipe.  But I have not used this one. 

White Slip

Grolleg                  34

OM4                      20

Custer Spar        27

Silica                    19

Add Zircopax   3

 

Roberta

[Callie Beller Diesel]

I use a lot of white slip decoration over red stoneware. Although there are slip recipes out there (check Glazy) I have a white stoneware clay body that I buy in dry bags and mix it to slip consistency rather than into a throwing clay. I find white stoneware slip tends to adhere better than porcelain slip. The shrinkage rates of the 2 clays I use closer to each other, so cracking is less of an issue if you’re laying on texture like I do. But whatever slip you wind up using has to be compatible with the clay you’ve got it over, so randomly suggesting white clays is maybe not as helpful as we could be without knowing what stoneware you’re using. 

If you’re putting a white slip over a darker clay, I find it’s only necessary to have it whiter than the underlying stoneware. The slip will  appear brighter in relation than it does on its own. 

[Min]

An engobe is going to be harder to fit to bisque clay than a slip going on leatherhard. Slip recipes or claybodies that contains ball clay are not going to be as white as one that doesn't, given the impurities in ball clay. You can add zircopax to compensate for this or use a recipe that doesn't contain ball clay. As for an engobe to use on bisque, have you tried using a white underglaze? 

Fish Sauce Slip works well for me on wet and leatherhard clay, it's very white as it is but can be made more so by adding up to 10 zircopax. In theory you can use it thinly on bisque too but I've had cracking with it when doing that, none when I used it on wet and leatherhard clay. It can be mixed up thickly to achieve textures if that's something you are interested in also. Bentone MA is expensive, if you need a large amount of slip (to dip pots in) then find the whitest bentonite you can and use double the amount. For brushing amounts I'ld use the Bentone MA.

I removed the bentonite from the original recipe and replaced it with 1/2 the amount of Bentone MA (aka macaloid) to reduce the specks you get with bentonite.

Fish Sauce - altered - cone 04 - 10

43.8 Grolleg 

15.6 Silica

23.5 Minspar

7.8 Pyrophyllite (this is crucial to the recipe)

4.7 Bentone MA

0 - 10 zircopax (optional)

total 95.4 without zircopax 

[Discus]

38 minutes ago, Callie Beller Diesel said:

I use a lot of white slip decoration over red stoneware. Although there are slip recipes out there (check Glazy) I have a white stoneware clay body that I buy in dry bags and mix it to slip consistency rather than into a throwing clay. I find white stoneware slip tends to adhere better than porcelain slip. The shrinkage rates of the 2 clays I use closer to each other, so cracking is less of an issue if you’re laying on texture like I do. But whatever slip you wind up using has to be compatible with the clay you’ve got it over, so randomly suggesting white clays is maybe not as helpful as we could be without knowing what stoneware you’re using. 

If you’re putting a white slip over a darker clay, I find it’s only necessary to have it whiter than the underlying stoneware. The slip will  appear brighter in relation than it does on its own. 

Hi Callie, Great...will take your advice and go for the stoneware white clay as a strong contender...am mostly going to use white/ buff stoneware so guess this will give me less or ,hopefully ,no compatibility problems.

[oldlady]

discus,  are you going to use a white stoneware for your work?    if that is what you plan, how would you use a white slip over it?   over buff, white slip would give a cleaner appearance to any decorative style you may be planning.   did i read this wrong?  can you say what you plan to do on the white surface?

[Discus]

Hi Old lady, I am ,loosely at the moment,  planning to use strong colours mixed with white slip to create pattern on top of white slipped stoneware.Hope this is feasible, or I guess simple stain and water but I do need white opaqueness.

[Callie Beller Diesel]

Do compare your shrinkage rates before you buy a whole bunch though. Not all of them are the same. 
Also, if you need a really stark white, you could try adding some zircopax to your slip base. 

[Discus]

Ok thanks Callie will check..and stark white is what I'm after.

[Discus]

17 hours ago, Min said:

An engobe is going to be harder to fit to bisque clay than a slip going on leatherhard. Slip recipes or claybodies that contains ball clay are not going to be as white as one that doesn't, given the impurities in ball clay. You can add zircopax to compensate for this or use a recipe that doesn't contain ball clay. As for an engobe to use on bisque, have you tried using a white underglaze? 

Fish Sauce Slip works well for me on wet and leatherhard clay, it's very white as it is but can be made more so by adding up to 10 zircopax. In theory you can use it thinly on bisque too but I've had cracking with it when doing that, none when I used it on wet and leatherhard clay. It can be mixed up thickly to achieve textures if that's something you are interested in also. Bentone MA is expensive, if you need a large amount of slip (to dip pots in) then find the whitest bentonite you can and use double the amount. For brushing amounts I'ld use the Bentone MA.

I removed the bentonite from the original recipe and replaced it with 1/2 the amount of Bentone MA (aka macaloid) to reduce the specks you get with bentonite.

Fish Sauce - altered - cone 04 - 10

43.8 Grolleg 

15.6 Silica

23.5 Minspar

7.8 Pyrophyllite (this is crucial to the recipe)

4.7 Bentone MA

0 - 10 zircopax (optional)

total 95.4 without zircopax 

Hi Min, That's great ! Thanks for all the information...looks like I've got something to get my teeth into now...the information out there in pottery books and Pinterest etc can be so vague and contradictory and therefore confusing!