Mixed last batch of epoxy wrong ratio...

[Mark42]

OOOOOHHHHHHH!!!!!! I must have messed up the ratio of my last epoxy batch. Lucky for me it was only 4 ounces. Should be a 3 to 1 mix resin to hardener. I think there was some resin left in the measuring cup so I didn't get a full ounce of hardener. So its a little short on hardner. Should have hardened 45 minutes ago, but instead is like syrup out of the refrigerator. It's getting hard/thicker, but not as fast as it should.

Think it will eventually harden? Or am I going to have to pull those pieces of glass out and wash everything down with alcohol.

DOH!

 

[Mark42]

Re: Mixed last batch of epoxy wrong ratio...

Its been about an hour and a half since the epoxy should have been hard. Now its hard, I can leave a finger nail mark in it, but it is hard. Guess about another hour and I can wash off all the anime blush from this mornings work and continue glassing. Been measuring and cutting pieces of glass while I wait. Good day for working, cool breeze, about 85 in the sun, 80 in the garage.

I guess there was enough hardener to make the reaction take, just a little slower than it should have.

Mark

 

[maxum247]

Re: Mixed last batch of epoxy wrong ratio...

Sounds like your in good shape, bout like useing slow hardner in hot weather.

 

[jonesg]

Re: Mixed last batch of epoxy wrong ratio...

I used to buy my epoxy directly from a chemist who worked for a big operation and did his own thing on the side in their factory, he said you can adjust ratios within a certain percentage, obviously not a lot.

I was buying lots of different types and he said to just buy 30 minute and 4 hr , then just mix to suit for times.

One thing I didn't think to try was to use less catalyst when adding silica to slow it down.

 

[Mark42]

Re: Mixed last batch of epoxy wrong ratio...

Well, it setup just fine. Hard as a rock. I was worried because the directons indicated that there is a narrow margine for mixing errors. I was afraid I would end up with a permanent sticky spot that would need cleanup.

I wasted over an hour of prime work time becaue of a simple mixing mistake.

Oh well, live and learn.

 

[Labman]

Re: Mixed last batch of epoxy wrong ratio...

Whew, glad it worked out for you. mixing inproperly is my biggest fear. All I have read here has given me the courage to go forward on my boat restore, but reading and doing aren't even close to the same thing.

 

[zach103]

Re: Mixed last batch of epoxy wrong ratio...

is it possible to have too much hardener ? i think i put to much in and now its acting like marks did

 

[proshadetree]

Re: Mixed last batch of epoxy wrong ratio...

Too much and it will kick off while your mixing it.You got to be close but there is quite a large margin of error

 

[zach103]

Re: Mixed last batch of epoxy wrong ratio...

it seems like some parts are starting to dry. i didn't start to gel while i was using it but then again i just mixed it and poured it down and took the brush to it

 

[Mark42]

Re: Mixed last batch of epoxy wrong ratio...

I think if you just give it time it will eventually harden. As long as the ratios are not way far off, it should work.

 

[zach103]

Re: Mixed last batch of epoxy wrong ratio...

its still tacky can i mix up another batch exact ratio and put it over it? would that harden?

 

[zach103]

Re: Mixed last batch of epoxy wrong ratio...

so i left the house around 5 today for uncles bday. just got home about 730.. i put down that resin yesterday around 5 today when i left at 5 it was still tacky enough where my feet were really sticking to it.. well i just got home and its not tacky at all.. what could of happened with in those 2 hours.. i had the fan on it all night

 

[Mark42]

Re: Mixed last batch of epoxy wrong ratio...

Epoxy and poly catalize different. With poly, the more hardener you add, the faster it sets. With epoxy, it is different, more "part B" may or may not make it cure faster. It seems that with epoxy, as long as there is enough mixed in, and mixed very well, it will eventually harden, but it is a lot more unpredicable than poly.

Bottom line is I prefer working with poly: 1)ease of sanding. 2) can use bondo filler as fairing, and it sands and smooths out well. 3) by far most boats are made from polyester or vinylester (the better of the two) resin. Boats made from poly resin in the 50's and 60's that were good designs are still around today.

Downside to poly: 1) smell of chemicals is much stronger, need good ventilation. 2) Poly resin goes bad after a few years on the shelf. 3) not as strong as epoxy, but as stated before, 40+year old boats are still in service built from poly. And poly gets better all the time. 3) Poly can be gel coated!!!!!! MAJOR PLUSS!!!!!

 

[Marcq]

Re: Mixed last batch of epoxy wrong ratio...

2) Poly resin goes bad after a few years on the shelf. [/B]

Unless I'm mistaken, I think it's epoxy that has a short shelf life

Marc..

 

[zach103]

Re: Mixed last batch of epoxy wrong ratio...

i guess it can be painted too. it was still a little tacky so i i put a layer of non skid down and it worked grea

 

[Tim Frank]

Re: Mixed last batch of epoxy wrong ratio...

Certainly a small batch makes for less accurate mix ratio since the remainder in the measuring cup is relatively consistant and so more of factor, but ambient conditions...humidity and surface temperature usually have a major effect also.

 

[jonesg]

Re: Mixed last batch of epoxy wrong ratio...

) Poly can be gel coated!!!!!! MAJOR PLUSS!!!!!

Epoxy molded parts can be pre-painted with epoxy paint,
if the inside of the mold is painted first it comes out like it was gel coated.
Its impossible to scratch the paint off.
I also found epoxy 2 part paint easier to handle than gelcoat.(spraying)

but price and ease of application won out in the end for poly.

I watched a freind work with poly resin in his auto shop, there I was counting 64 drops and he just eyeballs the catalyst bottle and gives a good squirt. !

 

[ondarvr]

Re: Mixed last batch of epoxy wrong ratio...

Keep counting the drops or get a measuring device, the glug glug method of measuring will eventually create problems and the need for the job to be redone.

For both epoxy and polyester just getting hard does not mean it cured correctly, even if it get's hard the physical properties can vary greatly if improperly catalyzed. For epoxy mix as directed, don't deviate from the recommended ratio, get it as close as possible and mix very well. For polyester there is a range, but it's important to stay within that range for best results.

 

[oops!]

Re: Mixed last batch of epoxy wrong ratio...

I wasted over an hour of prime work time becaue of a simple mixing mistake.

mixing inproperly is my biggest fear.

Keep counting the drops or get a measuring device, the glug glug method of measuring will eventually create problems and the need for the job to be redone.

i know pros that use the glug glug method.....they say theyve never had a problem!........thats because poly is so forgiving but that doesnt mean its cured right !......allways measure.....allways

For both epoxy and polyester just getting hard does not mean it cured correctly, even if it get's hard the physical properties can vary greatly if improperly catalyzed. For epoxy mix as directed, don't deviate from the recommended ratio, get it as close as possible and mix very well. For polyester there is a range, but it's important to stay within that range for best results.

one of the things is learned from the session at svfarah was..... all ingrediants must be mixed really well......

not just the resin/cat.....but the resin it self.....really shaken well....not just rolled around....but really really shaken or stired......hence the mixer paddle on the end of the drill in the hull ext thread.....even tho the poly/ resin is mixed well ....that doesnt mean the mix is complete if you just poured some waxed resin from the container with out really mixing the bulk resin....

mix every ingrediant till you think its mixed too much......then mix it some more !

 

[jonesg]

Re: Mixed last batch of epoxy wrong ratio...

They do measure, in reverse, they look at whats left in the catalyst bottle.
Half a can of resin, half a bottle of resin.

used to use a tool resin that was so thick on the bottom I stored it upside down to ease mixing before pouring it out.