How to measure out chemicals for glazing

[1Artsygirl]

I am new at making my own glaze from scratch and I am confused in regard to the mathematics of percentages/grams of materials needed. (EXAMPLE of 2 "fake" glazes )..

EXAMPLE 1

10 percent ferro frit.

30 percent epk,

60 percent feldspar.

NOT A REAL RECIPE... ok so I get that I need to measure out each ingredient to make a total of 100 percent. Well what if I want to make 5 gallons of the glaze.. how to I compute it into gallons needed?? And on top of that what if the recipe calls for extra ingredient's after 100% of whats needed is computed.

 

 

EXAMPLE 2

10 grams ferro frit,

30 grams epk,

60 grams feldspar. Equaling 100.

 

Well 100 grams does not make very much at all. I need buckets. Obviously I will make the small amounts first so I can test tile everything but when I'm ready ( I'm past ready), I will need enough to do over 100 pots in various colors..etc..

 

In short, what if I want a 5 gallon bucket of the glaze. Maybe I should request for totals of a 1 gallon bucket. I can just do the ingredients x 5 to get 5 gallons. I do have a very nice triple beam scale that I got recently. I feel pretty stupid asking the community for the help but I have been looking for a week now on how to figure this out..no answers so here I am.

Kind regards and thank's for any input.

( I knowwwww that I'm not "stupid" , I'm just a middle aged gal who hasn't used her math skills since Jr College

[justanassembler]

To answer your first questions, most glazes are calculated @ 100% minus their colorants--so your ingredients will equal 100% not counting colorants which are usually listed last on a recipe and will be small percentages of the total of most glazes.

 

In terms of your question regarding wet quantities, a rough rule of thumb is that 5-7lbs of glaze materials dry makes roughly a gallon wet. This of course differs a lot depending on the consistency of the glaze you are mixing, you'll have to do some testing on your specific recipes, but thats a rough guideline.

[TJR]

I can only give you my experience, so don't shoot the messenger.

1. An ice cream pail will hold a 1000 grams of glaze with water.

2.An average plastic pail that you get from a baker with tight fitting lid will hold 6,000 grams plus water.

3.10,000 grams of glaze will fit in the larger plastic pails

4.A styrofoam coffee cup will hold 100 grams of glaze for testing, which you should do first.

 

All glazes should be mixed dry first, then added to water.[use a dust mask]. Glazes are then sieved using a 80 mesh sieve, then re-sieved using a 100 mesh sieve. Buy these at your pottery supply store.

TJR

[Mark C.]

EXAMPLE 1

1000,Grams ferro frit.

3000,Grams epk,

6000,Grams feldspar.

 

 

EXAMPLE 2

1000.oo grams ferro frit,

3000.00 grams epk,

6000.00 grams feldspar. Equaling 10,000

 

I fixed these so they will make a little less than a 5 gallon bucket.

You can move the decimal or multiply them by whatever number you need.

Most of my glazes are 7.000-10,000 grams

I fill a bucket about 1/2 full or more then add the dry materials as I weight them-then power mix them and sieve them into the final bucket thru an 80 mesh.

Then add water slowly as I adjust them with a hydrometer.

I mix glaze about 1/4 of a day every two weeks

Mark

[Marcia Selsor]

Mark gives some good advice. five gallon make 7,000-10,000 depending on the density of the ingredients. Some chemicals are denser and occupy less space...fitting into a five gallon bucket easier than a glaze of less dense material like ash or magnesium carbonate.

maybe mix a batch of 1,000 grams and see if it fits into a half gallon container.

Marcia

[clay lover]

Have you tested a small amount of this glaze to see if it suits you and your clay before investing in a large amount? A 5 gallon bucket of a glaze can be a significant amount of something you find out you don't like.

[1Artsygirl]

Thank you all who have written me. In answer to my own question, So hers exactly what my problem is..In general... a recipe calls for percentages and I need to calculate the ingredients into grams. so changing percentage into grams. Is there a easy sure fire way to figure this every time? Man I feel not so smart..

 

Ok a new question is this....I have tested with small amounts of a transparent glaze with mason stains added. I had also bought a premixed ..powder.. Laguna birch white glaze that I plan on adding Mason stains to it also. With what I'm reading, 10% of a mason stain is what I need when mixing for colors added. Does anyone know if it's possible to add other dry ingredients to a premixed glaze? The birch white is Laguna WC-511 cone 5 glaze. Say I wanted a sea foam green...any suggestions kind regards, Penny

[atanzey]

The 'way' to calculate is to convert your percentage to a decimal and multiply by the total amount of glaze that you want to make. For instance, say you need 20% Ferro Frit and you're making a 1000 gram batch.

 

0.20 X 1000 = 200g

 

You have to do this every time, unless you always make the same size batches, and write it down for that size.

 

OR, if you have a spreadsheet program, you can automate it. Then you can set it up so that you change the batch size and it calculates for you. I attempted to attach a simplified copy of mine in Excel, but it didn't seem to 'take'.

 

Alice

[Marcia Selsor]

Thank you all who have written me. In answer to my own question, So hers exactly what my problem is..In general... a recipe calls for percentages and I need to calculate the ingredients into grams. so changing percentage into grams. Is there a easy sure fire way to figure this every time? Man I feel not so smart..

 

Ok a new question is this....I have tested with small amounts of a transparent glaze with mason stains added. I had also bought a premixed ..powder.. Laguna birch white glaze that I plan on adding Mason stains to it also. With what I'm reading, 10% of a mason stain is what I need when mixing for colors added. Does anyone know if it's possible to add other dry ingredients to a premixed glaze? The birch white is Laguna WC-511 cone 5 glaze. Say I wanted a sea foam green...any suggestions kind regards, Penny

 

yes you can add colorants to a clear glaze. For a pale sea green you could look at mason stains or try a little copper carbonate 1-3% for a start. Raw metal oxides can have different color effects depending on the base chemicals in the glazes...if it is alkaline or potash. Mason stains have reference codes which indicate what stains work with what chemicals , temperature limits etc.

http://www.bing.com/images/search?q=Mason+Stain+Chart&qpvt=Mason+Stain+Chart&FORM=IGRE

Marcia

[neilestrick]

My rule of thumb is that a glaze will fit 10,000 grams in a bucket only if the clay content is below 10%. At 10-12% I drop down to 9500 grams. At 13-16% 9000 grams. More clay than that I go to 8500 grams per 5 gallon bucket. Other ingredients will affect this, but clay has the greatest affect on how much water is needed in a glaze. More clay equals more water equals smaller batch.

 

Colorants are added in addition to the 100%. If you need 9% red iron oxide in a 9000 gram batch, you need 810 grams of iron in addition to the base glaze. Large quantities of colorants, such as 9% iron, will also require that you reduce the batch size.

[1Artsygirl]

Thank you again to all who have written me. I think I have it down pretty good now. Kind regards, Penny

[Mike.Kelly]

So I understand how to measure out the raw ingredients but how do you know how much water to add?  Do all glazes have the same specific gravity?  I found a couple of articles that talk about 1.75 as a "standard"  The recipes I have looked at so far have not mentioned amounts of water or the  final specific gravity. 

[Dick White]

I have found when mixing glazes that a good starting point of how much water to use is 1 liter of water per 1000g of dry batch. After it is mixed and has slaked for a day, you can add a bit more water if needed until it is at the proper consistency. A second observation from my experience, you don't want to make full buckets of glaze - they will spill and splash over the top when you mix and stir. The max I put in 5 gallon buckets is a 7500g batch. This is my practice, others may do it differently.

[Mike.Kelly]

Thanks Dick,  I plan on making about 1000g for my first dry batch.  The below recipe is one I plan to try.   Just to make sure I do fully understand how to measure out the correct weight.  The 5.26 and 8.00 represent the %  of the total weight of the 1000g i need to add for each additive.  So Zircopax would be 52.6g and Sky Blue would be 80g correct?

https://ceramicartsnetwork.org/ceramic-recipes/decorating-slips-engobes-and-terra-sigillatas/engobe-blue/

• Zircopax  5.26

• Mason Stain #6363 Sky Blue  8.00

[liambesaw]

1 hour ago, Mike.Kelly said:

So I understand how to measure out the raw ingredients but how do you know how much water to add?  Do all glazes have the same specific gravity?  I found a couple of articles that talk about 1.75 as a "standard"  The recipes I have looked at so far have not mentioned amounts of water or the  final specific gravity. 

The gravity depends on how it's used and your preference.  Brushing glazes are thicker, like 1.4-1.5, dipping are thinner, 1.6-1.75

[Callie Beller Diesel]

@Mike.Kelly your math is indeed correct. The glory of the metric system is that it's very easy to scale things with by simply moving the decimal place like that.

I am going to contradict liambesaw though: a specific gravity of 1.6 is denser than 1.4.  I mix my dipping glazes to somewhere in the 1.4-1.45 range. 1.6 would be entirely too thick for what I want. Mostly, measuring the SG of a glaze is done for your own frame of reference. Some of it will depend on how thick you want the glaze to go on, some will depend on how porous your bisque is, and some on how you're applying the glaze, as noted above. Once you get a bit of a feel of how thick (or not) a glaze needs to be applied, you record the sg so you can get repeatable results. 

[Min]

@Mike.Kelly, just a heads up with that recipe you linked to, well two heads up.

First one is the borax in the recipe needs to be dissolved in hot water then added to the wet mix. If the engobe sits around for a while, like more than a couple months or so, the borax can precipitate out of the mix and form little hard crystal bits as borax is water soluble. These need to be redissolved and added back to the mix. If you sieve your engobe before use and see little hard bits in the sieve you need to scrape them up and re-melt them. You can just use a bit of the glaze and microwave it with the borax crystals until the glaze is hot then add it back to the bucket.

Second heads up is since this is an engobe recipe it will need to be mixed with less water than a glaze. 

[liambesaw]

1 hour ago, Callie Beller Diesel said:

@Mike.Kelly your math is indeed correct. The glory of the metric system is that it's very easy to scale things with by simply moving the decimal place like that.

I am going to contradict liambesaw though: a specific gravity of 1.6 is denser than 1.4.  I mix my dipping glazes to somewhere in the 1.4-1.45 range. 1.6 would be entirely too thick for what I want. Mostly, measuring the SG of a glaze is done for your own frame of reference. Some of it will depend on how thick you want the glaze to go on, some will depend on how porous your bisque is, and some on how you're applying the glaze, as noted above. Once you get a bit of a feel of how thick (or not) a glaze needs to be applied, you record the sg so you can get repeatable results. 

Whoopsies, I had a 50:50 chance there, I dont mix for brushing and my hydrometer is made for alcohol, I do two ticks up from 'table wine' or 2 ticks down from 'beer'.  There is a video somewhere on CAD about making your own from a water bottle and some BBs. Any port in a storm I suppose.

[liambesaw]

1 hour ago, Min said:

@Mike.Kelly, just a heads up with that recipe you linked to, well two heads up.

First one is the borax in the recipe needs to be dissolved in hot water then added to the wet mix. If the engobe sits around for a while, like more than a couple months or so, the borax can precipitate out of the mix and form little hard crystal bits as borax is water soluble. These need to be redissolved and added back to the mix. If you sieve your engobe before use and see little hard bits in the sieve you need to scrape them up and re-melt them. You can just use a bit of the glaze and microwave it with the borax crystals until the glaze is hot then add it back to the bucket.

Second heads up is since this is an engobe recipe it will need to be mixed with less water than a glaze. 

So weird, that recipe calls it "engine" instead of "engobe" like 3 or 4 times.  I think someone went a little crazy with the spell checker.  Lots of flux in that bad boy, wonder what the reason for using borax is.

[Min]

9 minutes ago, liambesaw said:

So weird, that recipe calls it "engine" instead of "engobe" like 3 or 4 times.  I think someone went a little crazy with the spell checker.  Lots of flux in that bad boy, wonder what the reason for using borax is.

Borax is an early melting material, it helps the engobe bond with the pot. Engobes can have issues with shelling /peeling so the borax is helping to prevent that. 

[oldlady]

min, thanks for telling me what the little crystals were in the glaze that sat for a year or two.  you can tell i really liked that one, can't you!

a small note about %ages.   my potter friend's husband is an accountant.   he said that potters are the only people he knows whose totals come to more than 100%.    and we like it that way.

[dhPotter]

Rule of thumb for adding water is ---> 3 ounces of water per 100 gr dry material. 

[Mike.Kelly]

This is all great information.  Thanks you for the borax tip.  I would have been wondering what I did wrong.  Thanks again everybody.

[neilestrick]

@Mike.Kelly Remember that all of these recommendations are just starting points. There are not hard and fast rules for how much water is in a glaze, because every glaze is different, every clay body is different, and every potter is different. I mix several of my class glazes thicker than the others, because they need to be thicker to look good, and I have my student dip their pots for a count of 6. Others I mix thinner, because they run more. It's easier for them, rather than them trying to keep track of which can go thick and which can't. The glazes I use on my personal pots are mixed very thick, because it saves me from having to do a double dip.

[Mike.Kelly]

Thanks Neil.

The commercial dipping glazes I dip three test tiles for 2, 4, and 8 seconds.  I plan to do the same with the glazes I make from the recipes.   Then  I should be able to adjust the thickness accordingly.  Well that's the plan anyway.