System Three Silica Thickener, 1 Qt Tub, White

Use this with their microglass beads and it's much cheaper than most fillers. Sands easily if you mix it to peanut butter consistency. I used with WestSystems 105. Great fairing compound. Downside is that you have to mix two different powders which takes a few more seconds.

This material works great for stiffening the epoxy resin. I used it to fill holes where a kicker was mounted through the transom and to fill holes on the vertical.

I used it to thicken up finishing gelcoat when patching chips I got on the bottom and transom edges of my bass boat hull from floating onto sunken boulders while out fishing. Although some of the silica powder is clumpy in the container, as some reviewers have mentioned, it doesn't matter because you're going to mix it into the gelcoat resin anyway. Could not have done the patch repair without it, and would certainly buy it again.

Good

As mentioned by other reviewers, this product arrived filled with large and small clumps. It must be passed through a sieve prior to use, which is a bit of a mess. Once it's been sieved and broken down, it works just like you'd expect it to. For the price I would buy this again and deal with running it through a sieve, rather than pay the huge mark up on West Systems and other brands of fumed silica. Good value, just requires a bit of prep before use.

I added the silica to structural epoxy to repair a jet ski hull. This is an excellent product that mixes well with epoxy and provide strength. I can tell a significant difference between straight epoxy, and, epoxy mixed with silica. The straight epoxy sands very easily, but the silica epoxy takes several more passes for same results. It's easy to mix the silica into the epoxy, and I can guarantee you will not put in too much silica.

Building a mini tugboat. This filler thickens up epoxy resin very quickly. Seems to require a smaller amount than other fillers that I have used. When teh epocy cures, it makes for a very hard surface.

It works but as others have stated, it is lumpy. I tried to dry it out in the oven thinking it was humidity. After time in the oven, I put a couple silica packets in the container hoping it would help to keep the moisture down but neither the oven or packets helped. It remained clumpy. I have a kitchen sink drain strainer that I use over my can of mixed epoxy when I want to add the silica. I just push it through the strainer with my finger breaking all the clumps up to a fine powder. It does work but using a strainer is a bit of a pain in the butt. I needed more so I ended up ordering another brand which had excellent reviews. Hopefully that comes clump free....

Used for epoxy thicker filler, works very well

Only issue was some of the lumps were a pain to get mixed in. But it worked well and I only had a single exotherm due to the trying to get a few stubborn mixed in. It was a very hot day, so that didn't help either.