Prepping: The Water Sheet Test

Prepping a model horse is the art of preparing the surface for painting.

I was washing some artist resin models, and decided to try an experiment of a cleaning test technique from another hobby of mine.

(This technique can be used in a combination with other resin cleaning  methods, too.)

The Water Sheet Test is a technique that comes from vitreous (kiln-fired) enameling in prepping the surface to receive enamel.

Above are copper pieces, with and without enamel.

The process of enameling requires that the prepped metal surface be very clean, in order for the enamel (essentially glass powder) to fuse to the metal at around 1500 degrees in a kiln.

I will be painting an artist resin model horse for NaMoPaiMo (National Model Painting Month), and experimented with the water sheet test when washing several resins, to see if there were similar results to cleaning copper for enameling.

The experiment worked!

Artist resins often have an invisible coating of mold release, which is something that is applied to the inside of the mold before resin is poured into it, so that the resin doesn't adhere to it and allows the resin to be removed easily from the mold.

Artist resins must be thoroughly cleaned before priming and painting, often done with Comet cleaning powder, water, and a toothbrush.

Step 1: Run water on the resin.

Step 2: Take a look at the resin. 

See how the water is beading and seems to be repelling from the resin? 

The resin needs to be cleaned.

Step 3: This artist resin cow has been dampened and sprinkled with Comet powder. I wet the toothbrush and make sure to scrub the entire resin, especially any nooks and crannies.

(Note: you may want to wear gloves and/or eye protection, as this cleanser contains bleach and other chemicals, and the Comet paste sprays everywhere from the toothbrush! )

Step 4: Rinse resin to remove Comet.

Step 5: After removing the resin from the water, notice how the water is *sheeting*.(covering evenly across the model and not beading up.)

This means that this area is clean.

Run the model under the water a few times to check different areas to make sure that water is sheeting across the resin.

If you find a spot like above, where the water is beading/repelling, wash that area with Comet again.

Here is the same area after rewashing, and you can see how the water is sheeting across the model, instead of beading/repelling. 

This means that the surface is clean. 

(It doesn't hurt to wash the resin a second time to ensure that it is completely clean, or use other known resin cleaning methods.)

Video 1: Watch as the water repels off of the chest.

Video 2: After cleaning with a toothbrush and Comet, the water sheets across the chest instead of repelling.

Another quick view of the water sheet test:

Water beading/repelling after running resin under water. 

Needs to be cleaned.

Water sheeting evenly across model after running resin under water, following a scrubbing with Comet.

Continue prepping and priming to let the painting begin!