There are different techniques used to achieve a metallic finish with resin. "Cold-Casting" is a term used to describe the process of mixing metal powder with a translucent casting resin like Smooth-Cast® 325 and applying the mixture into a mold. The finished casting give the appearance and weight of solid metal. The metal cold-casting process is faster and much less expensive compared with foundry casting of molten metal. Different metal powders such as Bronze, Brass, Nickel Silver, Aluminum and Copper can be used depending on the desired effect.
We've recently added an additional step that involves wiping the finished casting with mineral spirits before abrading the surface with steel wool. We discovered this notably improves the finished cold cast metal effect.
Smooth-Cast® 325 casting resin, So-Strong® Black tint and Bronze powder are combined to make a 'Cold Cast' Bronze Casting. Any metal powder (-325 mesh) can be used including copper, brass, nickel/silver, etc.
Equal amounts of Smooth-Cast® 325 Part A, Part B and Bronze power are measured by volume.
Two drops of So-Strong® Black tint are added to Smooth-Cast® 325 Part B and thoroughly mixed.
Combine Smooth-Cast® 325 Part A......
Smooth-Cast® 325 Part B....
and the Bronze Powder into a mixing container and mix thoroughly.
Continually scrape the bottom and sides of the mixing container while stirring to keep the metal powder from settling on the bottom.
Pour the liquid into the center of the mold cavity. Silicone rubber works best for this application. This mold is made of Mold Max® XLS silicone rubber.
Immediately begin brushing the material around the mold cavity creating a 'gel coat'.
The mixture will continue to thicken as you brush. Once you feel the material starting to "gel" or "stick", stop brushing. Over brushing will result in a damaged casting. After brushing, let cure for 5 minutes.
Measure equal amounts of Smooth-Cast® 325 Part A and Part B by volume. Add a few drops of So-Strong® Black tint to Part B and mix.
Combine Smooth-Cast® 325 Part A with Part B in a clean mixing container.
Mix the material thoroughly, scraping the sides and bottom of the container several times.
Pour the liquid into the center of the mold cavity until full.
Allow the casting to cure for a minimum of 60 minutes before removing from the mold.
Finishing Stage: For best results, Mineral Spirits, medium/fine steel wool, and shoe polish are used to bring out the most realistic metal effect.
Begin by wiping down the entire surface of the model with a towel soaked in mineral spirits.
The mineral spirits will soften the plastic slightly and make it easier to bring out the metal shine when buffing with steel wool.
Abrade the casting using medium/fine steel wool until the desired metal shine and luster is attained.
Highlight the surface with black shoe polish to add depth and dimension.
Allow shoe polish to dry then buff with a soft cloth.
To prevent the oxidation of the metal, spray the polished piece with two coats of semi-gloss acrylic spray.
Finished Cold Cast Bronze piece.