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Need A White Matte Commercial Glaze Suggestion.


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I am asking for suggestions for matte white underglazes or engobes. I would also consider making my own engobe out of my white stoneware clay body but I don't know how. I've never done that. I need it to be able to be painted on bisque ware under my Clear Bright from Laguna. 

 

I have tried:

 

- Duncan Concepts white underglaze. It flares up and comes through the clear glaze. Yuck. That's not going to work. 

 

- Dune White engobe from Laguna. If applied too thickly it forms micro cracks along the edges. Since this is filling in carving ....  

 

I thought I would try Amaco's Velvet White but it says it is only food safe if I use it with their clear. I have extensively experimented with the Clear Bright and my clay bodies and I am not willing to change it. 

 

I have been making a series of highly decorated pie plates with carving and slip inlay. I paint wax on a leather-hard piece and then carve through to the clay, then paint it with white stoneware slip. 

 

The problem I am having is that the two most recent pieces I've made this way have been horribly pitted, tiny air bubbles formed when I painted on the slip and they did not show up until after it was fired. I thought I had them filled with the glaze but after glaze firing about 20 pits were still open, making a high-investment piece completely unusable. 

 

I want to try just carving it plain and painting on/wiping off an underglaze or engobe after it is bisque fired. 

 

This is not the item with the issues, this is another one that I made with the same technique. 

 

med_gallery_67168_1162_186117.jpg

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make a thin disc of your dark clay.  take it to very soft leatherhard and cover it with plastic.  

 

put some thin, dry pieces of your white stoneware clay into a container.  add some water.  wait overnight.  pour off any excess water and stir the clay and water very thoroughly with a stick blender.     try it over your dark clay test piece.  fire it and see whether the two are compatible.

 

don't ask me for the "correct" amount of white clay, who knows?  it is all adjustable by adding water or removing it by evaporation.  (a hair dryer helps speed it up)

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This goes from low fire to cone 10, the original recipe has bentonite in it, I replaced that with macaloid (and rebalanced). Works on greenware and bisque and is very white. Haven't tried doing what you are with wiping it down but I have used it on bisque with no problems on both red and white clay. If you want it even whiter you can add some zircopax to it but it's very white as is.

 

 

fish sauce slip (altered) 

 Minspar 200              27.50

 Grolleg Kaolin           40.80

 Pyrophyllite               8.30

 Silica                        17.00

 macaloid                   6.30

                                  99.90

 

fish sauce slip original 

 Minspar 200              23.50

 Grolleg Kaolin           43.60

 Pyrophyllite                 7.80

 Bentonite                    9.50

 Silica                         15.60

 

                                 100.00

 

edit: if you want to try this without going out and buying all the ingredients I can mail you a bit of the dry mix. pm me your address if you would like to.

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I think I've seen a video of you doing this wax/inlay technique on instagram. Refresh my memory, did you sponge off the excess white slip while it was still pretty wet? If so, that means your white slip has much more drying/shrinking to do than the dark pot. This would explain why it dries with pinholes. Most inlay demos that I've see involve scraping away the excess white slip when both clays are leatherhard, and have the same amount of shrinkage ahead of them. Also, scraping will compress both clays, while sponging will loosen up the slip even more.

 

Another suggestion would be to use a smaller tool and carve your designs with thinner lines. Less volume of white slip means the mismatch of shrinkage won't matter as much.

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make a thin disc of your dark clay.  take it to very soft leatherhard and cover it with plastic.  

 

put some thin, dry pieces of your white stoneware clay into a container.  add some water.  wait overnight.  pour off any excess water and stir the clay and water very thoroughly with a stick blender.     try it over your dark clay test piece.  fire it and see whether the two are compatible.

 

don't ask me for the "correct" amount of white clay, who knows?  it is all adjustable by adding water or removing it by evaporation.  (a hair dryer helps speed it up)

 

That's what I've been using up to now. They're compatible. I use it all the time on the interior of pots and for inlay. 

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+1 for the fish sauce. That stuff sticks to everything. I've even used it on bisque.

Also +1 for letting the slip set up longer. Everyone I know that does wax Mishima lets the inlay set up overnight before wiping. I tried some last year with some underglazes, and waiting overnight was particularly necessary because I think the binders in the UG were slowing down the drying.

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I think I've seen a video of you doing this wax/inlay technique on instagram. Refresh my memory, did you sponge off the excess white slip while it was still pretty wet? If so, that means your white slip has much more drying/shrinking to do than the dark pot. This would explain why it dries with pinholes. Most inlay demos that I've see involve scraping away the excess white slip when both clays are leatherhard, and have the same amount of shrinkage ahead of them. Also, scraping will compress both clays, while sponging will loosen up the slip even more.

 

Another suggestion would be to use a smaller tool and carve your designs with thinner lines. Less volume of white slip means the mismatch of shrinkage won't matter as much.

Yes, that's correct, that's the technique I'm using. However, it only works when the clay is still pretty wet, both for carving purposes and so the slip does not shrink away from the edges of the carving. This ONLY happens with this dark brown clay. I use this technique also on Moroccan Sand and Speckled Buff and have had zero issues with these pits even though everything is done the exact same way. 

 

It's not shrinking away from the sides. It's having tiny air bubbles trapped underneath that don't show up until the glaze firing when they shrink enough that they open and suck glaze into them creating a pit. 

 

I have tried carving it finer and then the design is lost. 

 

This is made with Speckled buff, zero pits, zero cracks. 

 

med_gallery_67168_1162_948853.jpg

 

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This goes from low fire to cone 10, the original recipe has bentonite in it, I replaced that with macaloid (and rebalanced). Works on greenware and bisque and is very white. Haven't tried doing what you are with wiping it down but I have used it on bisque with no problems on both red and white clay. If you want it even whiter you can add some zircopax to it but it's very white as is.

 

 

fish sauce slip (altered) 

 Minspar 200              27.50

 Grolleg Kaolin           40.80

 Pyrophyllite               8.30

 Silica                        17.00

 macaloid                   6.30

                                  99.90

 

fish sauce slip original 

 Minspar 200              23.50

 Grolleg Kaolin           43.60

 Pyrophyllite                 7.80

 Bentonite                    9.50

 Silica                         15.60

 

                                 100.00

 

edit: if you want to try this without going out and buying all the ingredients I can mail you a bit of the dry mix. pm me your address if you would like to.

 

Okay! I have never made a recipe like this before. But I know exactly where I can get the ingredients. How much water do I add?? Or do I just get it to the consistency that I need? 

 

I don't want it to be pure white, I like a slightly creamy white. 

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giselle, please read the second last sentence in your original question.  and the title of the whole thing.  anything more to clarify?  do you think the problem is with the slip (which you seem to interchangeably call an engobe) or the glaze after the slip is applied?  

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I re-read everything, and had a closer look at the product monographs for the stuff you've already tried. I'm willing to bet my favourite trimming tool that the products you've tried are 1) experiencing shrinkage incompatibilities with that dark clay body, and 2) the commercial engobe is beginning to vitrify before the red clay is done off-gassing.

 

Definitely mix up a batch of the fish sauce, because using it, or even a slip made from a white clay body I think will solve your issues. Apply it like you would normally, you don't need to apply it to bisque.

 

When you mix up slip, you are correct, just add enough water so that it's the consistency you want to work with. It's a bit slow to sieve, but you only really have to do it when you mix it up the first time or add to the batch.

 

This slip also won't come out that harsh, blue-white like the underglaze you listed. If you find the Grolleg to be too bright after you give it a test, we can try substituting some EPK, and I'll run it through my Insight to recalculate the flux for you.

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giselle, please read the second last sentence in your original question.  and the title of the whole thing.  anything more to clarify?  do you think the problem is with the slip (which you seem to interchangeably call an engobe) or the glaze after the slip is applied?  

 

It's definitely the slip, not the glaze. I wish I had taken pictures. But a little tiny bubble under the slip or inside the slip has opened enough to suck in the glaze and cause a pit. 

 

I'm so so sorry if I have not been clear in my posting!! :( LOL I always give all this information thinking I am being so clear and then when I read back over it I realize I have left important tidbits out! 

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The red clay that I use is called Hawaiian Red by Laguna. 

Good eye! Yes, I do paint white stoneware slip on the interior of all my pots made with darker clay. Many of my glazes change color in reaction to the minerals that give the clay its' color, and I like to have a really vibrant pop of color. Some of the speckles come through even two thick layers of slip, but it's definitely much less. Below you can see the bottom of one of the pie plates glazed in that same green, but with no layer of slip painted on. Quite a difference and you can see a toasty break where there were slightly higher points. 

 

med_gallery_67168_1162_1286451.jpg

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Giselle, let me muddy the waters even further.....I was at a Bill Van Gilder workshop last summer and the local studio had a recipe for what they called Porcelain Slip

EPK  50%  3 1/3 cups

Silica 24% 1 cup

Potash Feldspar (custer) 1 1/4 cup

 

I mixed this up at home and it is super white.  Even whiter than Don Davis Engobe.  So far it has behaved well on Speckled Buff and SB Red. 

 

Roberta

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Giselle, let me muddy the waters even further.....I was at a Bill Van Gilder workshop last summer and the local studio had a recipe for what they called Porcelain Slip

EPK  50%  3 1/3 cups

Silica 24% 1 cup

Potash Feldspar (custer) 1 1/4 cup

 

I mixed this up at home and it is super white.  Even whiter than Don Davis Engobe.  So far it has behaved well on Speckled Buff and SB Red. 

 

Roberta

 

Okay so I have never done my own glazes from scratch ... I know this is a slip recipe but I've never used a recipe for my slip. So I may want somebody to hold my hand when I try it. I'm going to talk to my clay supplier about these two recipes. The last time I asked him he not only gave me a kiln wash recipe but brought all the ingredients for me weighed out and ready to mix. :D 

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Giselle I love the way you sign your pots with the carved flower motif, what a great idea.

 

I don't always do that, I just did on this piece because it had the flowers everywhere else. But I especially like the bottoms on these pie plates as I continued the design on from the sides. 

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