[RotarySMP]

Hi Larry,

I also don't mean just larger rocks, leaving large voids to be filled with resin, you need all the grades from fine sand up to the rocks. In the volume occupied by a larger stone, the required resin is zero percent.

On the german site, http://5128.rapidforum.com/topic=110...8&search=beton

there are a few test peices guys have done, using various ratios of the different aggregate sizes and resin ratios. The guys are testing resin ratios from about 8% by weight, which is what the commercial outfits are using, up to about 12%.

The vibrating table seems to have a very large effect on the final result. They are also having some issue with mold releasing agents. I believe the highest quality cast to tolerance molds also use vaccuum degassing.

Any suggestions as to the best source of clean, graded rock (preferrably black

[Geof]

...Any suggestions as to the best source of clean, graded rock (preferrably black

I think one of the islands in the Tahiti group has beaches composed of sand from obsidian; guaranteed black and just a bit salty.