filling knots and cracks with sawdust and epoxy vs. sawdust and wood glue?

[Jeff]

Andy,

Gotcha. The hardeners in all epoxies are amines so they will smell kinda like ammonia (more fishy than ammonia). Because they're strong bases they will absorb water and carbon dioxide (combined=carbonic acid) from the atmosphere which definitely affects their performance. So the chemical crosslinking/polymerization doesn't happen so well; hence a soft, tacky, feel to it that never really hardens.

Resin is best cleaned from the pumps with acetone or methyl ethyl ketone (MEK) available at Lowes. The amine hardener is water soluble so soap and warm water will work (a little vinegar in that mix will improve its water solubility).

Here's what I received from the West technical folks:

Jeff:
Shelf life on 105 Resin and 205 Fast Hardener are indefinite for most applications short of building airplanes. For that we say three years on the resin and two years on the hardener. Having said that, I spoke to an old customer who says his 20 year old 105/205 is still curing fine.
We usually leave the pumps in the cans between uses- even if it is months or more before you need more epoxy. I’ve got resin/hardener containers with pumps in my home shop that are 5-6 years old and the pumps only come out when I’m adding resin or hardener or changing out the cans. You will want to put the containers on a drip tray like a plastic coffee can lid in the event that the pumps dips slightly over time. That way your shelves do not get sticky.
If you choose to clean the pumps and store them, the resin cleans best with lacquer thinner or acetone while 205 Hardener cleans up with warm soapy water.
Best regards,
Tom Pawlak
Technical Service

jscharver@verizon.net

 

[CarvedTones]

I will have to look at the thin hardener tonight and see if the maker (this is not West) has a site. It is the only hardener I have ever gotten that smells so strongly of ammonia. I mean open-at-arm's-length-or-cry-like-a-baby strong. I had assumed that was what they used to get it so thin. BTW, the only thing that hardener is good for is spreading a barrier coat; I won't ever order any more. The much older RAKA that still works fine has a much more subtle smell. It has been a few years since I bought any West. My biggest gripe with West is the price. If you search around for tests done on epoxy (you will find some done by boat builders. model rocket/plane makers and general industrial tests) they are always among the top few but all the vendors are pretty close because there is no secret ingredient (well maybe some tweaky stuff in hardeners). But it is pretty easy to find another name brand at savings of 25% or more compared to West and the more generic stuff from industrial suppliers is about half the price.

 

[Jeff]

Andy,

Good points! I don't use much epoxy so maybe the Loctite 5 minute stuff in the twin syringes can be more cost effective for the casual user; its only about $4-6/unit at Lowe's. Maybe worth trying to clean one of the 2 "mixing" nozzles in acetone or MEK for later re-use. :icon_scra

 

[CarvedTones]

Jeff,

Loc-Tite is probably the only brand that is more epensive, though only sort of. They are more expensive per unit but sell much smaller units so that your outlay is small. I bought the two separate small squeeze bottles for about $12 or so (I think) the last time I got any. The amount of epoxy in them is many times more than they put in the little syringes. For lamination jobs, where pricing is by the gallon, you generally find kits of a gallon of resin plus a half gallon of 2:1 hardener from nearly all the vendors and West will be around $100 or more, AeroMarine around $75, "Max Bond" (that is the brand of the thin hardener) around $50. As an interesting aside, US Composites sells their own labeled industrial epoxy for $69 for the similar 1.5 gallon kit yet also sells West at $80 for just the gallon of resin plus $30 or so for each of the 2 quarts of hardener you need. That's not the best price for the West, probably because they don't sell much of it, but it is interesting that they offer it.