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Enamel Pigmentation - Diy?


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#1 jonnie

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Posted 24 March 2014 - 07:55 AM

I would like to ask those with experience about pigmentation of enamels ( the type intended for use on metal ).

 

I am interested in creating "inbetween" colors for color graduations.

 

My experiments have been as follows...

 

1. Finely mix two differently colored powdered (opaque) enamels >>>  result - "spotty"

 

2. Finely mix, grind and sieve two powdered enamels >>> result - much better but still "spotty"

 

3. Finely mix, grind and fire ( typically 850 C | 1562 F ) two enamel powders, regrind, re-fire and repeat >>> result - best yet - hard to tell due to limitations in my method ( need to build a decent device for reducing larger flakes before grinding to a powder ).

 

4. Introduction of ceramic pigments from Thompson enamel supplies. I believe these are fritted and not pure oxides >>> result poor - pigment floats to the surface and is grainy. Not the desired result since I then go on to grind the surface smooth for a matt finish which is my preference - pigment is not taken into the body of the enamel its a superficial surface effect.

 

Any pointers to reference material or similar that will help me educate myself on the subject of how pigments are ( or are not ) fully absorbed into frits and glazes would be gratefully received.

 

At the moment I am working on the assumption that perhaps my temperature range ( traditional enamel temperatures up to 850 C | 1562 F ) are not capable of fully dissolving pigments into the glass - however I read somewhere that good pigments are insoluble in glass so I am probably off the mark here?

 

Bit confused!

 

Jon



#2 jonnie

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Posted 24 March 2014 - 08:19 AM

In case anyone finds it interesting... two pics.

The first (blue and white) shows a photo taken through my computer USB-microscope at 400x of a finely mixed blend of a light blue and off-white enamel showing total refusal to blend color at all.

The second (again 400x) shows the result of sprinkling a mustard colored ceramic pigment (from Thompson enamels) on a freshly ground off-white enamel surface - the whole lot was fired at around (850C | 1562 F) for a minute or so using a torch and then reground to remove the unwanted gloss finish. Some pigmentation does appear to have taken into the surface but I know from previous experiment that a few more passes with the diamond file and it would all be gone - its only superficial no real depth or penetration.

I have tried mixing the ceramic pigment into the enamel ( rather than just dusting on the surface as in the mustard colored case above ) but the results are again only skin deep as the pigment all seems to rise up to form a surface layer but nothing within the "body" of the enamel - three strokes of a diamond file and its all gone.

 

finelymixed

 

stainenamel
 
Again in brief I am hoping to connect with someone who can point me in the direction of information about how pigments are introduced to (enamel) frits and I suppose ultimately info on how to create a colored frit from scratch.
 
In reality I am happy to simply purchase existing powdered enamels and then to try and shift the color by small degrees to give myself an expanded palette to achieve amongst other things subtle color gradients.
 
Jon


#3 Tyler Miller

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Posted 24 March 2014 - 11:20 AM

How do your enamels fire without blending, just single colours as is out of the container?  My guess is that something's gone wrong if you can't get the commercial ceramic pigments to work.  How did Thompson advise you to proceed?



#4 jonnie

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Posted 24 March 2014 - 01:48 PM

How do your enamels fire without blending, just single colours as is out of the container?  My guess is that something's gone wrong if you can't get the commercial ceramic pigments to work.  How did Thompson advise you to proceed?

 

Hi Tyler,

 

I should have added in the original post that the intended use as far as Thompson are concerned is as a paint on surface pigmentation so it is performing as the manufacturer expects.

 

To answer your other question single color enamel (powders) are firing just fine.

 

Most of the enamaling texts/books suggest that true blending of colors is not possible but I guess I am asking is how the manufacturer managed an even dispersion of a pigment in the first case.

 

When I use a light blue enamel on its own I cannot magnify it sufficiently to see anything else but light blue - no pigment blotchiness appears its smooth and uniform.

 

What I am hoping to uncover here is whether I should be trying different pigments or whether my temperatures are simply too low to achieve real color blending. It might be the case that if someone wants to make an inbetween color from two other colors they need to fire to a much higher temperature for a longer time and then re-grind the result to get a new single color enamel?

 

I am getting the impression here that just because a glass or frit has fused its not necessarily really mixing or allowing diffusion of pigment in the way that many liquids would behave.

 

I am wondering whether temperature or "soak" time are variables that I need to explore. I could imagine going to the trouble of building a small high temperature kiln just for the purpose of being able to alter colors (from purchased 'base' colors) to my liking - it would be worth it for me.



#5 Tyler Miller

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Posted 24 March 2014 - 02:36 PM

Jon, you're right. Making glass and fusing glass are very different operations.  A tremendous amount of CO2 and other gases are released when making glass from raw materials.  Glass in ancient times was fired for as long as two weeks to get rid of all the CO2.  Frits are fired up to 1200C when made today to ensure good glass for the same reasons.

 

I hope this helps.  I do still think Thompson could help you get the most from your enamels and the pigments they supply.






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