One of our long time customers from History Stones sent me gorgeous photos of gray balusters he poured and installed. He was kind enough to share the recipe for his gray concrete mixture. I have included his instructions and photos below. He has used these baluster molds countless times over the last few years and has some really great tips that are also included in this post. Feel free to comment on this post if you have additional questions and I will be happy to get back to you!
White Portland Cement(94 pounds)
2.5 buckets of DOT sand(or equivalent) this is about 160 pounds of sand
1 bucket of pea rock(89 stone) about 60 pounds
4 ounces of Glennium 7500(this is a water reducer) not absolutely necessary but helps get a higher strength mix.
3 to 4 gallons of water(enough so there is a smooth consistency and concrete flows easily)
Color: per 94 pounds of cement, 200 grams of black color from Cement-It http://www.cement-it.com/
**Please note, there are many different types of black colorant each will give you a different shade of grey(or black if you add a lot of color to mix) to get the exact color in the mix you need to use the black sold by cement it.
**Balusters in the pictures provided are Acid washed after stripping from mold. The acid wash give a light sand finish and darkens the color a bit.
**To aide in getting a smoother finish (less bug holes), you can exclude using pearock in the mix.
**Be sure you use Fiberglass rebar in the baluster the steel rebar corrodes over time eventually cracking the baluster. We double up since balusters are so much work to do and it helps keep the necks from cracking between stripping, transport and installation.