How to thicken Epoxy resin

[Kody]

A question was asked some time ago about thickening epoxy resin. I couldn't remember the name of the stuff I used but here is all the good stuff about it.The thickening agent is called Cabosil and is the greatest stuff since sliced bread. It is the perfect stuff to use in wood if you have a thru hole for a bolt and don't want water to creep inside and cause dry rot. The way to do this is drill the hole at least 5 mm greater than the dia. of the bolt, then fill with epoxy thickened with Cabosil. When it is cured, re-drill the hole to the size of the bolt. No water will be able to seep into the wood as the epoxy/Cabosil has sealed the timber perfectly. It's the best stuff for use in thru boat hulls for attaching a towing point for skiers and similar. It is immensely strong.

http://www.epoxysystems.com/71.htm

To clean your hands or brushes after using epoxy resin, wash your hands etc. with a cheap white vinegar. Vinegar on a cloth is perfect for wiping up smears of resin when it is spread on your work areas or where a resin "run" has occurred on your job.
This agent is the perfect thing to use when filling screw holes, it does not crack off or fall out and does not shrink. I have never had a failure with it. It cost about $45.00 for a pound but a pound takes up a huge volume as it is so light. If you want some, try and go halves with your buddy. You will never regret using this stuff.

Kody

[asianflava]

There are several thickeners. Just make sure you are using the right one for the job. I used micro fibers to adhere the walls to the "studs" and micro balloons to fill as a filler. Sawdust is also a decent thickener on the cheap.

[Prem]

Note: Sawdust really weakens epoxy resin, unlike the inorganic thickeners (chopped glass strands, silica/Cabosil/microspheres). I've seen sawdust epoxy stay soft and crumbly and as such it doesn't sand smooth either. The wood particles will swell up and you no longer have a smooth, spreadable mixture. It's suddenly chunky. If you want it smooth and problem-free, use this: http://www.ebay.com/itm/MICROSPHERES-GLASS-BUBBLES-LOW-DENSITY-EPOXY-FILLER-/220528963762 (BTW, white flour and epoxy is bad too. Beach sand epoxy stays fluid and baking soda in epoxy sucks too. I haven't tried corn starch, but I recommend against it just on principle.)


For what it's worth,

Mr. Trial N. Error

[angib]

I would say there are three main 'thickening' agents:
- Silica, like Cabosil, which makes a very hard filler;
- Microfibres, smaller than chopped strands, which give tensile strength to a filler;
- Lightweight fillers, under lots of brand names, which are usually glass micro-balloons (literally little hollow bubbles of glass) which make a soft, easily sanded filler.

A pro has a stock of these dry filler materials and may mix a custom batch for each job, depending on the desired characteristics:
- just microfibres and epoxy makes a superb wood glue, if a little runny - easily stronger than plywood itself;
- adding a tiny amount of silica stiffens up the wood glue to give it the best gap-filling properties;
- equal proportions of each three fillers makes an excellent filleting material which is strong and hard when cured (not very easily sandable) and just soft enough to apply like a putty before curing;
- just silica can be used to make a rock-hard filler, but it won't be sandable by hand and will wear out sanding discs in an angle grinder pretty quick.

Some shops call microfibres 'scrambled egg' as they clump in the same way when they're dry.