Outdoor Gate - I thought I knew everything ...

[Bobby Slack]

Good morning fellow sawdust apron wearing hand plane pushing friends. I am building three gates and I used for joinery a Domino concept.

Since the dominos are too small for this 5' wide gate I made my own loose tenons out of Quarter Saw white oak.

Next I will use a dowel across and will fit the loose tenon tight on the stile and loose on the rail to allow wood movement. I will also after drilling the for the dowel will make the holes on the loose tenon on the bottom in an oblong shape to allow for movement.

Next ... glue.

I thought I knew everything and a friend introduced me to West Systems Epoxy.

What is the right mix?

I am going to use the 105 & 205 plus the 404 filler.

Any thoughts? Any words of advise?

[PaulMarcel]

I love that epoxy; so easy to use.

The right mix for 205 is 5 parts resin (only 1 resin: 105) to 1 part 205 hardener. You can mix by volume or weight. If you haven't ordered it yet, buy the pumps as they make measuring trivial. I always get mine at Jamestown Distributors and have several of their epoxy mixing dishes; these are really useful since the epoxy doesn't stick to them and the epoxy doesn't dissolve them.

Mix the 404 into the resin in your cup before adding the hardener or you'll be chewing away pot-life time blending. A very little 404 goes a long way; in a way, add enough 404 to your resin to have it a tad thicker than you want as adding the hardener will thin it out nicely. Very easy to make a fudge bar with too much 404.

I mentioned dissolving? I have little 1/4 cup portioning cups I use a lot in the shop; restaurants use them. For the size batch of epoxy I make, they are perfect! Not! Near the end of the pot life, the epoxy will have eaten through the bottom. That said, I use those epoxy dishes from JD.

If your mating parts are open-pored wood, I usually mix a little epoxy without the 404 and 'size' the joints with that since it will be able to seep in better than thickened epoxy. Follow up with the 404 thickened stuff. I might be over thinking that, but I've done it a few times and the stuff hasn't fallen apart yet

Usually when I'm done with the glue-up and things are in clamps, I put a thin smear of the left-over epoxy on an off-cut. When that is rock hard, I can take off the clamps. It isn't always obvious when it is set enough to remove clamps otherwise as the epoxy goes into a real "thick molasses" stage where it looks set, but can sag out of clamps.

Lastly, 5:1 is the ratio for 205 hardener. If you get other hardeners, verify the label. The tropical and super-clear hardeners have different ratios.

Okay, that was too much about epoxy... was waiting for my BSODed laptop to come back to life...

[Bobby Slack]

Paul-Marcel ... I have a few words

1. Thank you

2. Udaman

3. Thank you - Thank you - Thank you.

You made my research very easy.

By the way I bought the slow setting resin I think is the 206 so I have a half an hour to get things going.

And we shop at the same outfit.

I love that epoxy; so easy to use.

The right mix for 205 is 5 parts resin (only 1 resin: 105) to 1 part 205 hardener. You can mix by volume or weight. If you haven't ordered it yet, buy the pumps as they make measuring trivial. I always get mine at Jamestown Distributors and have several of their epoxy mixing dishes; these are really useful since the epoxy doesn't stick to them and the epoxy doesn't dissolve them.

Mix the 404 into the resin in your cup before adding the hardener or you'll be chewing away pot-life time blending. A very little 404 goes a long way; in a way, add enough 404 to your resin to have it a tad thicker than you want as adding the hardener will thin it out nicely. Very easy to make a fudge bar with too much 404.

I mentioned dissolving? I have little 1/4 cup portioning cups I use a lot in the shop; restaurants use them. For the size batch of epoxy I make, they are perfect! Not! Near the end of the pot life, the epoxy will have eaten through the bottom. That said, I use those epoxy dishes from JD.

If your mating parts are open-pored wood, I usually mix a little epoxy without the 404 and 'size' the joints with that since it will be able to seep in better than thickened epoxy. Follow up with the 404 thickened stuff. I might be over thinking that, but I've done it a few times and the stuff hasn't fallen apart yet

Usually when I'm done with the glue-up and things are in clamps, I put a thin smear of the left-over epoxy on an off-cut. When that is rock hard, I can take off the clamps. It isn't always obvious when it is set enough to remove clamps otherwise as the epoxy goes into a real "thick molasses" stage where it looks set, but can sag out of clamps.

Lastly, 5:1 is the ratio for 205 hardener. If you get other hardeners, verify the label. The tropical and super-clear hardeners have different ratios.

Okay, that was too much about epoxy... was waiting for my BSODed laptop to come back to life...

[PaulMarcel]

Ah you're welcome. You said 205 in your original posting so read the 206 can for proper portioning. There are instructions for using it with the pump (basically which pump to use) and for wearing flats...er, sorry, pumpless And yeah you will have a lot more time. Actually just looked at my can and 206 has 5:1 portioning just like 205.

Another trick to slowing the set is to keep the resin or hardener or both in the fridge. It's a bit thicker from the cold when you first mix it, but otherwise smooths out by the time you are done stirring. Adds a lot more time. In summer out here, I put them both in the beer fridge.

Someone once told me that you can slow the set by cheating the hardener. If you don't put enough, the result is a partially hardened bond; it'll feel fully set but in a way it's a rigid matrix of cross-linked resin with unlinked resin in between; significantly weaker. Too much hardener will set it in a heartbeat but also makes it weaker, though I'm not sure why that's true in this case.

[Don Z.]

The reason the extra hardener cures faster is that you have extra molecules available for linking... but the reason it's weaker is you end up with a lot of uncured resin in the mix. If memory serves, it's called "stoichiometry".

The pumps are great, but sometimes you'll get an air bubble, and mess up the ratio. So sometimes it's better to pump into containers on a scale, so you're sure you're getting what you think you're getting. Also, read the label. The ratio by weight is "slightly" different than the ratio by volume. For instance, the System 3 epoxy I use on my boat is a 2:1 ratio by volume, but 44%/56% by weight. West has the info on their web site, on the label, and if all else fails they have a great tech support line.

[SignWave]

With Epoxy (and that's what we are talking about here), the ratio is important, and deviating either way will cause a weaker cure. The best way to modify cure times is to use a different hardener, or change the temperature (as mentioned by Paul-Marcel, above).

My understanding is that with fiberglass resin (i.e. not epoxy), you can change the speed of curing by modifying the amount of hardener somewhat, and within reason keep the same strength.