A Slick Coat is a “grease” coat applied to a surface in preparation for a Glazing Medium application. A slick coat is made of a clear solution and is usually applied with a roller, sponge, mist spray, or rag.
The purpose of greasing the surface is to allow the next layer to be moved and manipulated easier and stay open longer. Adding a greasy slick coat before a veining step (with crystallization) can allow for better blending into the previous step.
Most commonly, a slick coat is used on large or sensitive surfaces or substates. However, as seen in a previous post about red griotte marble, a slick coat was used in the activation step of a faux marble.
When the previous coat is absorbent, the water-based glaze in the next layer will be sucked up at a faster rate than a non-absorbent surface. A chalky surface when covered with a glazing medium, for instance, dries at an increased rate and therefore has a shorter open time for a decorative finish. This type of surface would be absorbent and difficult to work with.
Some absorbent surfaces/substrates are:
- Flat or satin paint
- Applied textures
- Raw wood (when staining over a light wood, use a stain conditioner as a slick coat).
The downside of using a slick coat is that it’s an extra step. Also, the curing time could be extended and prevent a quick finish of the final steps.
First, step is to know the surface material. Test the absorbency of your surface area using a wet sponge and wipe off an area. If the color of the substrate turns lighter or darker or changes colors once the water has evaporated, you know there is a transfer of moisture. A chalky surface is difficult to work with and will need a slick coat applied prior to your glaze. Mix and apply your slick coat in the manner below.
FOR WATER-BASED MEDIUMS: A slick coat for water applications could consist of 100% water (perhaps misted or sponged onto the surface). More often though it’s 2 parts water to 1 part Glazing Medium that will create a slick coat that will not only fight the absorption rate but nourish the surface.
After applying the slick coat above, the water-based glazing medium in the next layer will be absorbed by the surface below at a slower rate.