What are sponges made out of?

[surbitonPete]

I have tried quite a few different sponge materials because at least they don't have threads that might get onto the heating coil but just as the others have said it holds on to the liquid too well ..I couldn't find any with good wicking properties.

[bri1270]

I've confirmed that the Fluval Foam filters are indeed a very porous, almost honeycomb like polyester sponge. Seems to be perfect for our purposes. It doesn't stick to the atomizers in stringy bits and pull off like the Water Polishing pads or the polyfill. It wicks very nicely, holds a good amount of liquid. Don't overfill and don't leave your e-cig upright as you will flood the atomizer. I found a good rinsing before using helps, and they seem to be durable enough to stand up to quite a few cleanings as well. Here's a link:

FOAM BLOCK FOR FLUVAL 404 - 2 PK | HAGEN | SPONGES & FOAM | FILTER MEDIA & CARTRIDGES


The difference in the various sizes from 104 to 405 seems to be in length and width. Thickness remains constant. I also opened up the different sizes at Petco and they all had the same consistency. I went with the 404/405 because I thought it would yield the most cart re-packs.