I have found somewhere I can buy fine, medium, coarse grades etc so I look forward to hearing about which is best. I don't want finished products where you can see white lumps, so I assume most people use fine grade, but can't find this info specified anywhere.

Thank you for your advice!

Most people use medium horticultural grade perlite. If you use a recipe with perlite you will see white specks. If you don't want white lumps/specks use a recipe without perlite.

Thank you very much for your reply, billie_ann. Most helpful.

I don't mind white specks, just not large lumps, if you know what I mean!

I've never made hypertufa before, just preparing to for the first time, and most of the pieces I see online do have white specks which look OK and it seems like perlite is ideal to keep things light weight.

Is there a particular reason NOT to use fine perlite, I guess I'm wondering?

If there wasn't a reason not to, I thought it might keep things light weight but be less visible in the final product...

Was also thinking, since some people use sand instead of perlite, and sand has very small particles, possibly that means that fine perlite would be OK?

Sand is used for strength. I use some sand in all my recipes.
Regarding fine grade perlite, I've never used fine perlite.

Thank you again. I saw the fine and the medium grades and decided to get the medium. The fine would be hard to work with I think, half of it is like a powder.

You use sand too, that's interesting. What's your favourite recipe?

I use different recipes for different looks and applications.
Rustic look, lumpy peat moss recipe.
Modern look, white Portland cement with vermiculite.
Carving, any of the recipes with fine grade ingredients.
I use sand in all of the recipes. No fiber.

Oh wow, you really do know what you're doing.

Do you use 1/4 sand in each or it varies depending upon application?

Bear in mind the more sand you use the heavier the object becomes. It depends on what you are making ...and you have to adjust the ratios to suit your needs.

Ah, I see what you mean, thanks.