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Epoxy -will it harden

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Forum topic by snowdog posted 09-10-2011 01:30 PM 2717 views 0 times favorited 12 replies Add to Favorites Watch
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snowdog

1132 posts in 2737 days


09-10-2011 01:30 PM

Topic tags/keywords: epoxy

I messed up and was not paying attention to detail and did not use enough hardener in the mix. Will it ever harden?
It was approximately:
1 to .70 mix
Epoxy to Hardener:

-- "so much to learn and so little time"..


12 replies so far

View patron's profile

patron

13184 posts in 2095 days


#1 posted 09-10-2011 01:38 PM

with any hardener at all
it should be fine

i have had to wait for 4-5 days sometimes
as i just eyeball the mix

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

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snowdog

1132 posts in 2737 days


#2 posted 09-10-2011 01:49 PM

I dislike when I mess up something so simple, no fool like an old fool. At least I usually only make a mistake once, but there are so many things that can go wrong that I always find another thing to mess up. At least I do not have to make the same mistake twice <laugh> to keep making mistakes.

-- "so much to learn and so little time"..

View Keith Fenton's profile

Keith Fenton

323 posts in 1674 days


#3 posted 09-10-2011 02:27 PM

I don’t speak from personal experience but it is my understanding that epoxy is a 2-part mixture with each molecule needing a corresponding molecule of hardener to bond with chemically in order for it to harden. It’s not like a resin/catalyst reaction like with fiberglass where less catalyst just slows down the hardening process.

-- Scroll saw patterns @ http://www.sheilalandrydesigns.com

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CharlieM1958

15820 posts in 2972 days


#4 posted 09-10-2011 02:31 PM

Once you pass 50, everything takes longer to get hard.

-- Charlie M. "Woodworking - patience = firewood"

View degoose's profile

degoose

7052 posts in 2109 days


#5 posted 09-10-2011 10:35 PM

Charlie, now you tell me…

-- Drink twice... and don't bother to cut... @ lazylarrywoodworks.com.au For lovers of all things timber...

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snowdog

1132 posts in 2737 days


#6 posted 09-11-2011 01:54 PM

That is funny Charlie but I thought it was the longevity of the system that took a toll after 50 :)

-- "so much to learn and so little time"..

View MrRon's profile

MrRon

2991 posts in 1997 days


#7 posted 09-11-2011 04:50 PM

Keith, There are many different mix combinations. They are formulated by the manufacturer to suit different requirements; some for strength, some for speed, some for convenience (2:1).

View mafe's profile

mafe

9690 posts in 1843 days


#8 posted 09-11-2011 05:38 PM

Pls tell us if it did.
I have only once tried that it was impossible, but I think the product was bad…
Otherwise time solves it, but I suspect it will not be as strong.
Best thoughts,
Mads

-- Mad F, the fanatical rhykenologist and vintage architect. Democraticwoodworking.

View shipwright's profile

shipwright

5319 posts in 1552 days


#9 posted 09-11-2011 07:07 PM

Kieth is right. Epoxies (true epoxies, you never know what someone may market as an epoxy) are sold in two parts because the are two reagents in a chemical reaction that will form a polymer. When mixed they will react and form new molecules in what ever ratio is required (like the 2:1 ratio for hydrogen and oxygen to make water)

If, when all the available partner molecules for one reagent are consumed, there are still molecules of one or the other in the mix they will prevent the material from achieving it’s potential in hardness, strength, etc.

These effects can be minimal with some cases and catastrophic in others. A few spare molecules is no big deal but if you are dealing with a 5:1 mix and you mix it 1:1 you will have a big sticky mess to clean up.

This is completely different than catalyst reactions like polyester where all the reagents are already present in the resin but won’t react without the presence of a catalyst (MEK for polyester). In these reactions the more catalyst you add the faster they will react. The only way you can speed up epoxy is with heat.

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

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mafe

9690 posts in 1843 days


#10 posted 09-11-2011 10:00 PM

Not too hot!
You can acually micowave epoxy joints and take them apart, I do that in my knife making.
Also I make it more easy floading with heat before it dry up, but don’t try this with the fast version.
Best thoughts,
Mads

-- Mad F, the fanatical rhykenologist and vintage architect. Democraticwoodworking.

View WoodNuts's profile

WoodNuts

74 posts in 1702 days


#11 posted 09-12-2011 09:43 AM

Hey Charlie, he didn’t ask how to push a rope.

-- ...there's a fix fer dat...

View snowdog's profile

snowdog

1132 posts in 2737 days


#12 posted 09-12-2011 12:42 PM

The epoxy was some no named brand I got at a local hobby shop to glue my air plane wings together. It has hardened after 4 days to the point that I feel confident in its ability to stay together <laugh> There is a carbon fiber tube adding rigidity to the wing so I will test fly it this week when the weather is a bit nicer and see if I can crash it :)

Here is a pic of the plane , and no that is not me, just a pic from the hobby shop. (http://www.horizonhobby.com/Products/Default.aspx?ProdID=EFL2725)

-- "so much to learn and so little time"..

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