Glaze Testing - Fastest Way To Test Colorant Percent Increases.

[Joseph Fireborn]

*this has already been answered, I am just putting it here because Chilly wanted it to be archived for future searches, i asked a simple question in whats on your mind part of the forums, i just expected a few yes that will work answers, or no it wont, but I ended up with a lot of good information.*

 

Original Question: Trying to figure out the fastest way to test colorant % increases. Thinking 500ML of base glaze, then suck out 50ML into cups, add % into each one and mix?

 

Mark (Marko) Madrazo

That sounds like a good plan. 

 

Joseph F.

I have 3 stains that I love the color of, and I want to test 1% increases up to 5%. I can't think of a faster way to do 15 batches for test tiles. 

 

Joseph F.

Except I will need 750ML instead of 500ML. Brain Overload. 

 

Marcia Selsor

I just used clear cups and equally divided them into ten cups equal level. 

 

Joseph F.

Then add the dry stain? 

 

High Bridge Pottery

I use surface gravity 1.5 to be equal to 0.8g dry material per ml of glaze. Take 50ml you have 40g of glaze so 0.4g is 1%. Add dry into cup first then syringing in mixes mostly for you. 

 

High Bridge Pottery

dry colouring oxides

 

Joseph F.

Thanks for tips Joel. 

 

GEP

Your approach should work. For those tiny batches, stirring in the dry stain should be ok (no need to sieve each one). Stir fast and change directions while stirring. 

 

Joseph F.

I will give it a shot tomorrow, thanks for all the quick tips everyone. 

 

High Bridge Pottery

You could also do a line blend then you only have to weigh out the colouring oxide once. 

 

Marcia Selsor

after during into plastic cups equally, yes, added stains and colorants. whatever you want to add. 

 

Marcia Selsor

I also sieve each cup with a small talisman or comparable sieve

 

David Woodin

You are blending Cup A #1 to cup B #6, so you have 6 small containers set out A has a 300 gram batch of base, B has 300 gram batch of base plus 5% stain. 

# 1 #2 #3 #4 #5 #6
A 100 80 60 40 20 0 all in cc
B 0 20 40 60 80 100 all in cc
But 300 gram batch is too much material so I use 150 gram than I halve the cc amounts in the above table that is where the original post amounts came from, The results are still cup 2 1%, cup 3 2%, cup 4 3%, cup 5 4%, cup 6 5%

[High Bridge Pottery]

I agree with David, go with the line blend for quickest and least work.

[glazenerd]

Joseph:

From what I have read, the suggestions involve testing on flat surfaces: tiles or currie grid. There is however a method to test multiples of increase on a vertical surfaces. I believe Diane Creber (Canada) mentions it in her book on Crystalline Glazes, and is also used by Meredith Bunzl of Germany. It involves making a simple sombrero shaped piece with upturned rim to catch excessive flow. This shape is divided into 5-6 segments with increasing percentages of colorants. You can also stamp parts of each segment to test flow effects. I tried finding a demo link, but could not come up with one. I could make one this week, and post it later: a picture would help. In crystalline glazes:there is a vast difference in color between flat and vertical surtaxes.

Nerd

[Joseph Fireborn]

So I did what I had originally intended. I mixed up a batch of 750G, added the % stain to each cup, then syringed in 50ml, this was the first time using the syringe. I felt like the process was incredibly easy. Weighing out the stain was probably the slowest part, although I dont mind that part because I have a really good .00 gram scale and it makes that job really easy. The whole process to mix 15 glazes and dip and label took about an hour. I am pretty happy with that speed of testing. The one thing I need to improve is to find a better method to mix the little 85ml cups. A teaspoon was to big and was tedious so I ended up using the end of a paintbrush and I stirred each one about 1 minute each. I am thinking I just need to get a tiny spoon from a kids playset or something at a garage sale. One thing I didn't care for was tossing out all that glaze. I mean it wasn't a lot, but it felt wasteful, but I guess its part of the beast. 

 

I also used one of my bisque currie tiles to put the same glazes on there flat, so I have both vertical and flat test of the 15 glazes. I should have taken the time to experiment with titanium and other things under and on top of the glazes with the remaining currie tiles, but tbh, I am just looking for my celadon at this point.

 

Once I nail down a celadon I am going to move back into testing silicon carbide on stoneware for chemical reduction at cone 6 ox. While in the meantime selling porcelain pots with celadon. 

 

Thanks for all the help everyone with your ideas and comments on ways to do this. It was helpful. 

[oldlady]

joseph, when i was testing colors, i used only 10 grams of dry glaze for each test.  that is about a tablespoonful of glaze. granted, i was just trying to find a reaction of any kind and did only 5% and 10%.  weighed out,  the amount of color was about.the amount that sits on one of the kemper tools with the curved end.  and mixing with a paintbrush was simple.  very little left to toss out.  

 

i used the typical glaze test tile with a brush to apply it.  5% on one side and 10% on the other.  i could get 4 tests on one slice of the test tile that way on about a 2 inch wide wedge.

[Joseph Fireborn]

Oldlady: That is a good idea, I will have to tinker with it.

 

I liked being able to dip the tile as that is going to be how I plan on applying the glaze to my porcelain, so that has some merit. In general I wasn't to upset about the waste, I mean 750g's of glaze is probably less than a few dollars, so not a huge deal, I usually keep my test batches for later testing if I change clays and stuff, but I dont plan on changing clay for a while. I love this 365 porcelain its probably the best porcelain I have ever thrown. I throw almost all my pots off the hump nowadays, and I haven't had any cracks from open drying, I literally sit the pot out for an hour and flip it as the rim drys that quick, then I trim the next day at a little past leather hard. 

 

Do you find that the brushing gives you an accurate image of what a dipped pot will look like?

 

EDIT: I forgot that it wasn't even really 750g's of glaze as I still probably have enough glaze in the bin that I kept the base in to make another 15 cups. So that will prove useful later on. Mistyped. Should be 5 more cups.

[oldlady]

i did not say in my post that the glaze is dry when i measure it out.  i guess i assumed you were doing the same thing.  should not assume.

 

i was looking for color, some base glazes and some mason stains do not play well with each other.  my rough testing let me see that yes, combining clear with mason stain #xxx gave me a yellow or combining the same clear with mason stain #yyy gave me clear with no color.  refining the percentages came later.

 

i have been trying to get something like a true celadon for years but have been unsuccessful.  the mason stain named celadon has an opacifier that immediately ruins any hope of a celadon glaze look, that deep, transparent, elusive hint of color that true celadon glaze has.

 

i do not dip glaze, nor do i brush it.  i single fire and spray the glaze on.  the brush test, again, was to see if there was anything to pursue.

 

there are 375 test tiles in this pile.  not a good way to keep them.  the wider one with 2 blues is a test of Vivid blue and Mazerine blue because i had just been given those 2 colors.  the pinks are 5% and 10%.

[Joseph Fireborn]

Oldlady that is a lot of tiles!

I posted some of my blue celadon test pots. In my gallery. Jar is a bit light for my taste. I should have 15 celadon tiles to post tomorrow, using the method from above.

 

[Marcia Selsor]

Joseph,

When I taught triaxial blends I had students mix 250 grams. add water. Pour into 5 cups evenly. Then add colorants.Sieve each cup with one of those small sieves. From 5 cups we got 15 blends using a spoonful of one and a spoonful of another. It can easily be expanded. Applied the mix by pouring with a spoon. Thats how we applied glaze. Pour or dip.Number tiles 1-15 first row straight from the cups, next all mixed with 1, next row mixed with 2 etc.

Marcia

 

1 2 3 4 5 1,2,3,4,5

6 7 8 9 1+ 2, 3,4,5

10 11 12 2+ 3, 4,5

13 14 3+ 4,5

15 4+5

[Joseph Fireborn]

I am learning so much. It's overwhelming how much time I have been wasting lol. 

 

You people are amazing.

[neilestrick]

To test % increases- take 200g of the base glaze plus the lowest % of colorant, mix with water and blend with a stick blender. Dip a tile. Add the amount of colorant to get to the next %, blend and dip a tile. Repeat until done. The last tiles will be slightly off from the exact percentage, but it's more than accurate enough for a first round of tests. For the second round I'll run exact percentage tests for my target tile plus 1% above and below. It only takes a couple minutes to do a full blend from 2-10% in 2% increments.

[Joseph Fireborn]

To test % increases- take 200g of the base glaze plus the lowest % of colorant, mix with water and blend with a stick blender. Dip a tile. Add the amount of colorant to get to the next %, blend and dip a tile. Repeat until done. The last tiles will be slightly off from the exact percentage, but it's more than accurate enough for a first round of tests. For the second round I'll run exact percentage tests for my target tile plus 1% above and below. It only takes a couple minutes to do a full blend from 2-10% in 2% increments.

 

I thought about doing this, but I wasn't sure it would be close to accurate at all. I thought about your second round of test and that helping solve the problem, but in the end I went with the other method. 

 

I am still going to run a 2nd round of test on the 15 cup method, because I have never done it before, but I suppose it should be pretty darn close. 

 

It is crazy how many different ways there are to do simple things. 

[Min]

There is a faster way of measuring the stains than weighing out each one. I saw Robin Hopper do this at a demo years ago. Basically you weigh out the max amount of stain or oxide/carb or opacifier you are going to use then press the material into a square and cut it into sections then start with the smallest amount, add that to the base glaze and work your way up through all the sections until you've used all the material.

 

Hopper's facebook page has an explantion on it here: https://www.facebook.com/permalink.php?story_fbid=725025390897282&id=507476852652138

[Marcia Selsor]

Joseph,

I edited the 15 cup to be more explanatory. I gave out worksheets with % of various oxides like

5% rulte, 2%cobalt carb, etc. Remember that for 50 grams 1% = 0.5 grams

when mixed with 50% more of the base it drops to .25%

Marcia