I'm trying to make a (better) ground glass for an old 4x5 reducing back I have, but I'm not quite happy with the results, compared to my other 4x5 camera (Horseman Woodman).
It seems the grinding powder I have is too coarse...

Now, I've checked locally for suitable silicon carbide (?), but all the suppliers I contacted sell minimum quantities which are waaaay too big (and expensive) for me. I've also checked online in USA and elsewhere, and managed to find a few sellers, but the shipping costs to Croatia are really expensive (orders of magnitude more expensive than the product itself...).

So, I'm asking other DIY types here: perhaps someone has some #600 grit silicon carbide that they would be willing to ship to Croatia? I need a relatively small quantity (enough to make several GGs), which would most likely fit into a standard-size envelope (3-4 ounces, i.e. about 0.1 kg at the most should be more than enough, I guess...).

Of course, I'm willing to pay for the material and shipping - and I suppose the shipping should be much less than the standard $45-$50 the online sellers are asking

I'm not sure why they charge so much for shipping: perhaps the silicon carbide requires some special forms to be filled or something? It's not as if it's a hazardous substance, AFAIK....

Thanks in advance,