Glass speed funnels, try this guy
I had one which was very old which I acquired from a clean up at the old US Mint assay office in NYC. The assay office closed in the early 1980's and it was like a museum as all it did was gravimetric assays. The funnels were probably 100 years old. The grooves were much deeper and it was awesome. Until gravity kicked in and it became a million shards of glass. The newer ones still have grooves just not as pronounced.
The reason a typical smooth glass funnel is not as fast is the paper seals flat on the glass and the liquid cannot pass through it efficiently. Simply lifting the paper so it cannot seal to the glass and can drain after going through the paper makes it very effective. Gotta love simplicity.
I had one which was very old which I acquired from a clean up at the old US Mint assay office in NYC. The assay office closed in the early 1980's and it was like a museum as all it did was gravimetric assays. The funnels were probably 100 years old. The grooves were much deeper and it was awesome. Until gravity kicked in and it became a million shards of glass. The newer ones still have grooves just not as pronounced.
The reason a typical smooth glass funnel is not as fast is the paper seals flat on the glass and the liquid cannot pass through it efficiently. Simply lifting the paper so it cannot seal to the glass and can drain after going through the paper makes it very effective. Gotta love simplicity.