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Are all epoxys the same?

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Forum topic by tdrury posted 03-03-2016 01:19 PM 529 views 0 times favorited 12 replies Add to Favorites Watch
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tdrury

4 posts in 279 days


03-03-2016 01:19 PM

Hi,

I am in need of some epoxy for gluing up a project, locally I can only get small 2 part tubes, bar top epoxy and epoxy resin for fiberglass.

Has anyone tried using bar top epoxy or fiberglass resin for joinery work? it is much cheaper than west systems for the same volume (and I can get it locally).

I would consider ordering west systems, however, I a concerned with ordering it this time of year, I live in the far north and things have a tendency to freeze on the way up, I have had the misfortune of using several glues and epoxy that have frozen on a truck and the result is a sticky mess.

any insight would be great. thanks


12 replies so far

View MrUnix's profile

MrUnix

4225 posts in 1663 days


#1 posted 03-03-2016 02:07 PM

I use west system epoxy a lot, and their FAQ states that freezing will not hurt it. Other Mfg’s are similar… although at least one recommends not letting it freeze for an extended period of time (as in days/weeks). BTW: West system is ‘epoxy for fiberglass’, although most fiberglass applications are done with polyester resin instead, as it’s much cheaper than epoxy. “Bar top” epoxy is, AFAIK, just a thinner epoxy that cures clear (and west has their 207 hardener that will cure clear as well).

As for gluing.. depends on what you are using it on. You can check the web site for recommendations on what additives are needed for certain applications… For example, when I make laminated sailboat tillers, I add micro-fibers to help filling small gaps and imperfections between laminations.

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

View Ger21's profile

Ger21

1047 posts in 2595 days


#2 posted 03-03-2016 02:23 PM

and epoxy resin for fiberglass.

“Fiberglass resin” is actually polyester resin, and is nothing like epoxy. It’s not an adhesive, and shouldn’t be used as one.

No, not all epoxy is created equal.
I use epoxy from US Composites, which costs about 1/3 what West System epoxy costs.
I would consider West and the other premium brands to maybe be a little bit better, but not 3x better.

I use the medium hardener, which takes an hour or two to set up in the winter (60°).
If you’re using it to glue wood, I’d recommend getting some West High Density filler to add to the epoxy.

Cold does not hurt epoxy, as long as it’s warmed up before using.
I just used 1/2 gallon in the last two weeks that’s been in my unheated garage for 2 years, and it was still fine.

I just placed an order yesterday. 1/2 gallon of resin + hardener is about $40. Don’t forget to order pumps.

-- Gerry, http://www.thecncwoodworker.com/index.html http://www.jointcam.com

View ChrisK's profile

ChrisK

1809 posts in 2545 days


#3 posted 03-03-2016 02:26 PM

http://www.westsystem.com/ss/product-selection-chart/

West would suggest that not all epoxies are the same. HD and Lowes sell large qty 2 part systems that are a little cheaper. Depends on how much you need.

-- Chris K

View MalcolmLaurel's profile

MalcolmLaurel

269 posts in 1087 days


#4 posted 03-03-2016 02:29 PM

West System or T-88 are the standard epoxies for building wooden airplanes.

-- Malcolm Laurel - http://MalcolmLaurel.com

View Ger21's profile

Ger21

1047 posts in 2595 days


#5 posted 03-03-2016 02:33 PM

I also recommend reading all of the technical info on the West System website. Lots of great information on different ways to use epoxy.

-- Gerry, http://www.thecncwoodworker.com/index.html http://www.jointcam.com

View shipwright's profile

shipwright

7170 posts in 2262 days


#6 posted 03-03-2016 03:27 PM

+1 most of what Ger21 said.
If you work in a cold climate however I would suggest you look into Cold Cure by System Three. I used to build cold moulded boats on Vancouver Island and used many gallons of the stuff. WEST has no equivalent. It also dries with no amine blush which makes for much easier sanding.

As for fillers and thickeners (they are very different animals) have a look at this blog. http://lumberjocks.com/shipwright/blog/series/4499

-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fibreglass trees. http://thecanadianschooloffrenchmarquetry.com/

View SignWave's profile

SignWave

320 posts in 2499 days


#7 posted 03-03-2016 04:02 PM

I’ve had good luck with U.S. Composites epoxy. Much better price than West Systems, and perfectly fine for what I want to do.

-- Barry, http://BarrysWorkshop.com/

View tdrury's profile

tdrury

4 posts in 279 days


#8 posted 03-03-2016 06:11 PM

Wow, thanks for all the really useful advice, so glad I asked.

Cold Cure looks like it might be just what I am looking for.

Cheers

View runswithscissors's profile

runswithscissors

2189 posts in 1489 days


#9 posted 03-03-2016 10:38 PM

Epoxy exposed to cold over extended periods can crystalize, similar to honey in a jar. The treatment is the same—warm it up. I place the bottle of epoxy in a tub or bucket of quite warm water, and leave it there until the crystals are re-disolved. Doesn’t hurt the epoxy at all.

I, too have used System III epoxies, and find their products very satisfactory.

-- I admit to being an adrenaline junky; fortunately, I'm very easily frightened

View tdrury's profile

tdrury

4 posts in 279 days


#10 posted 03-03-2016 10:46 PM

What would cause the last batch of epoxy I used to not harden? it was the type that comes in 2 equal volume tubes, I mixed the entirety of both tubes together (equal parts as per directions) and after 3 days my laminated rockers remained a ruined sticky mess. I performed the glue up in a heated space (my office at work).

Bad batch of big box store epoxy perhaps?

this was the second time gluing up these rockers, the first time was with titebond 3 (which I suspect had been frozen) and the rockers delaminated after removing from the clamping jig. Could it be the wood species? It is a rather waxy wood, tiger wood.

Cheers

View shipwright's profile

shipwright

7170 posts in 2262 days


#11 posted 03-03-2016 11:54 PM

Waxy wood shouldn’t make the epoxy refuse to cure. My best guess if you got the proportions accurate (as it sounds that you did) would be incomplete mixing. If your epoxy is not “bad” and you have accurate proportions, good temperature and thorough mixing, it will set. That’s about all there is.
There are other reasons that a bent lamination might fail in epoxy, like too much clamping pressure (bad thing with epoxy) but that won’t prevent curing.

-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fibreglass trees. http://thecanadianschooloffrenchmarquetry.com/

View runswithscissors's profile

runswithscissors

2189 posts in 1489 days


#12 posted 03-04-2016 01:20 AM

I have zero confidence in the epoxy tubes that supposedly “mix” the epoxy by squeezing it through twisty passages. Epoxy needs to be very thoroughly mixed. And by the way, adding extra hardener does not speed up the cure. In fact, it may interfere with it.

Though I agree waxy wood shouldn’t have any effect on epoxy curing, it may not make a strong, permanent bond. Teak, an oily wood, can be epoxied, but needs treatment first with acetone just before gluing. I’m not familiar with tiger wood (except for a golfer with a similar name), but it may require the same preparation.

I like to add some kind of fiber to epoxy when using it as a glue. My go-to is wood flour from the sander, mixing enough to give a peanut butter consistency (not crunchy style).

-- I admit to being an adrenaline junky; fortunately, I'm very easily frightened

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