Gum Arabic ratio to water

[Carl_and16]

Hi,

My understanding of gum arabic is it helps with the application of glazes when brushing them on - is that correct? My glazes to date have all been good but I find that when they dry they turn quite powdery, which compared to some of the commercial glazes, is quite significant. So before a firing I have to be really cautious about how I handle them so as to not leave spots where I've removed the glaze with my hands. Will adding gum arabic help with this? Another issue that I've found is that when brushing on the glazes in layers, some of the 'base' layers underneath are removed at the same time, so the final fired vessel looks quite patchy. This also seems to be less of an issue compared with some of the commercial glazes. Again, as far as I can tell from other forums, this seems to resolve the issue. One last thing - Does anyone know what the ratio of gum arabic is to water when mixing it with raw materials?

Thanks in advance for any advice!

Thanks,

Carl

[dhPotter]

I would try adding clay to the glaze recipe. Clay helps the glaze adhere to the pot. Whatever your glaze calls for , EPK or Ball Clay, add 5%. See if this helps, If not add 5% more.

 

[Benzine]

Any dip glaze, I've ever used, commercial, or otherwise, have been quite powdery, when dry.  The commercial, brush on glazes, do use additives, which make them more brushable.  It does seem to also make them come off a bit less too. 

It's honestly not an issue,  if you aren't handling them much, post glaze application.

[Min]

1/2 to 1% gum should do it. Dry gum in with the other dry ingredients, don't try and add it to a wet glaze.  Or mix up a solution of gum plus very hot water and use that for about 1/3 of the water content of the glaze. Gum will rot so either just make up enough to use fairly soon or add a tiny bit of copper carbonate to act as a preservative. 1 gallon of gum concentrate solution to 1/4 tsp copper carb. Like dhPotter said though, if you can redo the recipe to get more clay into it that will take care of the powdering issue. 

[Kakes]

On 10/5/2018 at 2:06 PM, Min said:

1/2 to 1% gum should do it. Dry gum in with the other dry ingredients, don't try and add it to a wet glaze.  Or mix up a solution of gum plus very hot water and use that for about 1/3 of the water content of the glaze. Gum will rot so either just make up enough to use fairly soon or add a tiny bit of copper carbonate to act as a preservative. 1 gallon of gum concentrate solution to 1/4 tsp copper carb. Like dhPotter said though, if you can redo the recipe to get more clay into it that will take care of the powdering issue. 

Hi Min, What are the proportions of gum to water when mixing up a gum solution?

And is this (adding gum either dry or wet) the best way to make a glaze easier to brush on? I'm not so concerned with it adhering to the surface as brushing on a smooth-ish layer.

thank you.

[liambesaw]

10 minutes ago, Kakes said:

Hi Min, What are the proportions of gum to water when mixing up a gum solution?

And is this (adding gum either dry or wet) the best way to make a glaze easier to brush on? I'm not so concerned with it adhering to the surface as brushing on a smooth-ish layer.

thank you.

A lot of people add cmc gum or even macloid to address both issues of brushablilty and binding.  It improves brushability by slowing the drying process.

[neilestrick]

To make a brushing glaze, first mix up a gum solution:

Add 2 tablespoons CMC Gum and 1/4 teaspoon copper carb to a gallon of water. Shake it up gently and let it sit overnight. The next day, mix well with an immersion blender. Then use the gum solution in place of about 1/3 of the water when you mix your glaze.

Adding clay to your recipe will alter the melt of the glaze. If you're not dipping the glaze, then the gum solution is the way to go. If you're dipping, then trying to get more clay into the recipe is good, however you'll have to run a lot of tests to see how much clay you can add without changing the melt.