You can apply Gel Stain to MDF, stained surfaces and most painted surfaces, including milk paint, chalk paint and latex paint. Sanding down to raw wood would be the very best practice but the following is the most common prep - it only takes a few minutes:
FIRST: clean your project with a Scotch Brite pad and a 50/50 mix of denatured alcohol and water.
SECOND, sand with 150 or 180 grit, we recommend the Softback Sanding Sponges, not messy and they last forever. Sanding is critical to the success of every finishing project as it further cleans the surface and opens up the grain to improve the adhesion of the new finish. The glossier the original finish is, the more important is to sand to open up the surface.
GEL STAIN OVER MDF. Clean the surface. Because MDF is not as absorbent as natural wood, let the piece dry for a couple of days in-between coats and before applying top coat. For top coats, we recommend water base High Performance if you want a clear coat with quick dry time or Arm-R-Seal oil based polyurethane if you want more ambering qualities. The High Performance can be brushed or sprayed on, and the Arm-R-seal can be wiped on or brushed on.
We are not a fan of putting Gel Stain on laminate, not much adheres to laminate very well because these surfaces are specifically designed NOT to mar, and probably not "sandable ". If you can abrade the surface with something, you may have success. Folks have successfully put Gel Stain on more surfaces than we ever dreamed of, including fiber glass, so if you want to proceed, TEST your procedure on a hidden area first and let cure for 14 days. Then further test the finish by duplicating normal wear and tear: washing, scrubbing, scratching, etc to see if the finish bonds to the surface. It might not adhere. Let us know if any of you have a success story and the techniques used. We get this question all the time because many cabinets have laminate on the sides and on the toe kicks. A safer option is Dark Chocolate Milk Paint.
We do not recommend using our gels over WHITE laminate. Again, Milk Paint would be a better product to use. We have heard of success with the following preparation. Clean the surface. Prep with XIM 400 White Primer Sealer Bonder. Once you have your laminate primed use General Finishes Dark Chocolate Milk Paint, it matches the Java gel stain color. Finish with 2-3 coats of High performance top coat.
Here is the scoop on XIM 400 White Primer Sealer Bonder.
Solvent Born, Bonding Primer Sealer
1. Properties of both a primer and an adhesive
2. Makes paint stick to tough-to-paint surfaces, including ceramic tile, porcelain, glass, Formica and melamine laminates, PVC, fiberglass, many plastics, aluminum, many metals, wood
3. Very fast drying
4. Tintable to pastel colors with universal tint colors
5. Interior / Exterior applications
6. Top coat with oil-alkyds and latexes in 60 minutes