A Word About Varnishing

Let's talk a little about polymer clay varnish

After much internet research and testing, I've found Varathane to be the best varnish to date. Look for, "Varathane Crystal Clear Water-Based Polyurethane Heavy Use Formula". It comes in a choice of Gloss, Semi-Gloss and a Satin formula. Mine was purchased from my local Ace Hardware in the half pint container. 

Varathane comes in water based and oil based versions.  When using this varnish for polymer clay make sure you purchase the WATER based version.

Let me start by saying I don't use varnish on the majority of my projects.  Baked polymer clay is durable. It holds up to washing, wear and weathering.  


All the clay needs is a good buffing to bring out a nice shiny surface. Just use a buffing cloth like cotton, terrycloth or denim. Rub vigorously with either of these cloths for several minutes. If using a power or electric buffer instead, a cloth or muslin wheel is best. With the buffer remember to keep the clay moving at all times. Keeping the buffer in one spot will cause gouges in the clay.


Using A Varnish
I use varnish for several reasons:

1. To achieve a glass-like shine that cannot be obtained with buffing alone. 
2. To seal in powders, some paints or thin metal sheets. If not sealed they wear over time due to rubbing against clothing or skin.
3. To change the clay's appearance. Varnish helps to make colors POP! Translucents appear to be more translucent while the colors in powders and glitters will intensify.

To varnish or not to varnish? Choose from matted, semi-gloss or glossy depending on the desired outcome.

How To Apply
Gently stir the Varathane in it's container to make sure it's mixed.  I found that shaking the container will cause air bubbles to occur.  Then, pour a small amount into a disposable cup. To achieve a shiny surface make sure to apply many very thin coats that are allowed to dry between coatings.  I either use a small paint brush (brushing in only one direction) or using a damp, wrung out foam sponge. With the sponge it's recommended to dab, dab, dab, then drag, drag, drag across the same area to achieve a thin, even coat for the first thin layer.  All subsequent layers should be a pattern of dab, dab, dab, wait 30 seconds, and then one draw across the area you're working on. 


Wait for the first layer to dry completely before adding another coat. The varnish will dry clear in color.  I usually allow 15 - 30 minutes of drying time. If I find myself in a hurry, I have sped up the drying process by using a heat gun. If you decide to use a heat gun, just make sure you don't hold the heat gun constantly over any single area.  Keep the heat moving or you can burn the varnish. Another way to sped up drying time is to add a little water to thin out the varnish. Thinning out the varnish will make the finish not as intense. 

If I desire a glass like finish I'll use wet/dry sand paper before varnishing. Pieces are sanded using 500, 1000, 2000, 4000 grit (in that order). After sanding, the pieces are washed and dried completely to remove any dust.


Baking Is The Cure
The last step I perform is baking the clay after I have applied the desired coats and let the piece dry completely. Some other experts recommend placing the piece in the oven after every coat. If you choose this method just make sure to let the piece completely cool between baking. Not letting the piece cool completely will make the varnish turn orange.

I have seen all types of temperature tips when baking the varnish. I just use the baking directions listed on the package of the clay I'm using. I'll bake the varnished piece for 10 - 15 minutes. Baking instead of air drying is recommended to cure and dry the piece to a diamond hard cure. If air drying alone, this cure can take several days to a week.

When the Varathane is cured it becomes water resistant. If you are into making any types of buttons or use fabrics with your work, this is good information because the piece will also hold up to washing.   

Is Kato Compatible?
I haven't tried sealing the Kato brand of clay with varnish. I've read the Kato brand of polymer clay is designed to repel water. This characteristic doesn't allow a good bond between the water based varnish and the clay.  It is suggested to give the Kato brand a alcohol wash before applying any water based varnish. 

Don't Do It
When I first began using polymer clay back in 2008, there was much talk about using finger nail polish as a sealer.  DON'T DO IT.  It's been found that over time the surface of the clay will become sticky.

If you decide to use anything other than water based Varathane just make sure you test a piece of your finished clay first.