Latex Resist: A Surface Tool

 
 

By Kip O'Krongly

In my last post, I talked about green glazing and single firing.  As part of that single firing process, all of my surface work is completed prior to the first trip into the kiln.  In order to build up enough surface depth before firing, I've found latex resist to be an invaluable tool.  It allows me to mask out areas while I'm working, but gives me the flexibility to peel it away for additional layers like glaze and terra sigillata (without having to burn off something like wax!). An additional perk of latex is that if you make a mistake, all you have to do is wait ten minutes and you can peel it off and start again.  Yay to forgiving materials and processes!

In this post, I'll walk you through adding a colored background using latex resist to mask out areas of sgraffito. First up, a little information on what kind of latex I use and how to get the best results!

Latexing tools...

Latexing tools...

I have found Laguna's Water Based Latex to be a great option for this process.  While it does have an odor, it's not nearly as smelly as the ammonia based latex types and it gives a strong coverage that stands up well to brushing and sponging over.  (A note of warning, however: This product does have a shelf life.  As it ages, it will begin to clump when you brush it on and start to smell horrifically bad - typically after having around for a 8 - 10 months...)

A few important notes for latex use:

  1. When your latex arrives, you'll want to thin it to the consistency of heavy cream with water (distilled is best).
  2. While you can add water to the latex itself, your brush can NEVER touch water (for some reason, this makes the latex seize up on the brush).  When you are prepping to latex, run your brush through straight dish soap to thoroughly coat the bristles. 
  3. Wipe off the excess soap from the brush on a paper towel before dipping in the latex.
  4. Periodically while latexing, "rinse" your brush again in the soap.
  5. Do a final (extra thorough!) soap rinse when you're done before putting your brush away - again no water!
  6. Lastly, the latex MUST be removed prior to firing.  Burning rubber isn't such a lovely thing...

Now onto the application! The piece below is ready for masking and adding a colored background.  I typically hand paint in the cloud areas with underglaze and then coat both the animals and clouds in one go.

An oval bowl with sgraffito decoration ready to resist!  Note that the rim of the piece was also latexed - I do that prior to slipping the surface so that the rims and feet are easy to clean up.

An oval bowl with sgraffito decoration ready to resist!  Note that the rim of the piece was also latexed - I do that prior to slipping the surface so that the rims and feet are easy to clean up.

Below I'm beginning to cover the drawn areas with a solid coat of the liquid latex - sometimes it can take a few coats to get good coverage.  If it's too thin, it's a royal pain to peel up later.  With latex, thicker is better!

One tricky part of this technique is knowing how long to let the latex set before continuing to add surface.  When I use latex on the rims and feet, the pieces are much wetter, so the latex needs to set for much longer before being fully cured.  (I've done a few tests and 3.5 hours seems to be the minimum wait time in this case).  At the stage above however, the piece has dried out quite a bit during sgraffito work so 20 minutes tends to do the trick.

With the latex set up, it's time for color!  I spend a lot of time at this stage on blending the colors into each other for a gradient effect.  It's still something that I'm working on - do I use a dry brush or a wet brush?  Do I mix the colors together on the piece or off?  How many colors to use?  I'm still learning a lot about this process...  To see captions for the images below, click on an individual image:

Now comes the really fun part - peeling up the latex!  I typically use tweezers to lift an area and then gently pull the rubber from the surface:

The big reveal!

The big reveal!

Check out the detail picked up by the latex:

And finally, the finished piece, ready for green glazing:

If you'd like more information on green glazing, check out my previous post, Bye, Bye, Bisque for the process and firing schedule!

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