Thread: A quick epoxy question....

Ask the supplier for a Technical Data Sheet and a Safety Data Sheet on the product. The TDS should have the info you require about recommended applications etc.

A basic difference - generally, casting resins have a low viscosity so that the mix self-levels and flows easily into voids. Adhesive resins tend to have much higher viscosity so that sufficient mix remains to make the joint secure.

Ah, that is so logical and makes perfect sense. Thanks.

Mobyturns is absolutely correct, but I would have answered your question differently.

I use WEST System epoxy, almost always the slow hardening version #209).

• If I want it to flow, such as wetting out grain, then I just add a bit of acetone or MEK,
• If I want to thicken it for a glue up I just add a thickener,
• If I want to do a fillet, then I add a lot more thickener.

Ther is little difference between any of the well known brands except advertising hype. I suggest that you stick to one only, and get to know its ideosyncracies.

Thanks again, Graeme.
Some years ago I owned a timber boat that was built in the 1920s. I recall I used a bit of West System stuff when I had that.
The painful memories of those 'old timber boat owning' years have now dimmed, so I feel ready to refamiliarize myself with epoxy.
I'll probably opt for the 206 hardener - not too quick, but not too slow.
When you write a 'thickener', so you mean a filler?
Is it one of these you use?

Fillers | West System | Leaders in Marine Epoxy

Originally Posted by scottbr

... I'll probably opt for the 206 hardener - not too quick, but not too slow.

When you write a 'thickener', so you mean a filler?
Is it one of these you use?

Fillers | West System | Leaders in Marine Epoxy

I much prefer the slower #209 hardener to the standard #206 for three main reasons:

• It gives me a lot more time; I don't like to be rushed,
• It is an absolute pain if resin starts to go off too soon - stop, clean up and start again, and
• Much lower risk of heat build-up in the resin (often termed exothermic reaction).

Whether it is a thickener or a filler largely depends on how much you put in. I use three:

• Colloidal silica (WEST #406) - magic stuff - This thickens epoxy but also makes it cohesive which means that it both self-smooths and also resists slumping on vertical surfaces.
• Microspheres (#411) - Used to thicken into a putty, for filling holes or doing fillets. IMO, saw dust works just as well.
• Saw dust (actually ROS sander dust) - I have jars of Huon pine, celery top pine, mountain ash, blackwood and sassafras dust. Used the same as #411, works just as well and far less visible.

I usually blend a little #406 with fillers as it gives a smoother mixture.

Microballoons (#417) - Like #411 these are as fine as talcum powder but are hollow and ultra light - apparently, under a microscope, they look like pingpong balls. They are ultra light - breath on them and they blow away, stir a little too hard and they jump out of the tin, they float high on top of the resin and are hard too mix. An absolute PIA. Marketing-wise, they are targeted at yachties who want to spend $1,000 to save a kilogram of weight. I hate them!

Thanks again, Graeme.

I like the mental picture I have of your jars of sawdust.