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martynball
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Hello, im struggling to get my head around the mix ratio for the eproxy resin. On the containers, it says 100 - 30, is this measured by weight, or quantity?
Let's say I wanted to use a small amount of resin for example 5 KG in weight? How do I work out how much harder to use?
I have made a mixture and it's been drying for 24 hours, however its still tacky, im assuming I have not used enough hardner?
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oekmont
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With epoxy it is not about using enough hardener, but to use exactly the right amount of hardener. Therefore hardener ist the wrong word. Better think of component a and component b instead of resin and hardener.
100:30 means that for every 100 units (weight) of component a (resin) you should mix in 30 units of component b.
An easy way would be to think in units of 130.
For example : 5kg = 5000g = 38,5 units of 130g.
Wich means 38,5 x 100g = 3850g component a and 38,5 x 30g = 1155g component b
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Matt (Staff)
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+xWith epoxy it is not about using enough hardener, but to use exactly the right amount of hardener. Therefore hardener ist the wrong word. Better think of component a and component b instead of resin and hardener. 100:30 means that for every 100 units (weight) of component a (resin) you should mix in 30 units of component b. An easy way would be to think in units of 130. For example : 5kg = 5000g = 38,5 units of 130g. Wich means 38,5 x 100g = 3850g component a and 38,5 x 30g = 1155g component b Couldn't say it better, this is exactly right. For every two-part product that we sell, the mix ratio we provide is in part-by-weight, not parts-by-volume. Because the density of the materials (the density of the resin vs the density of the hardener) are different, this means that you can't use the parts-by-weight ratio as a parts-by-volume ratio. We chose parts by weight because it's generally a much more accurate way of measuring (for a number of reasons). The only exception across our whole range is ArtResin (which uses a 1:1 by volume mix ratio) or when measuring MEKP catalyst into polyester resin or vinylester resin in which case most people use a catalyst dispenser bottle to measure catalyst in by volume.
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Matt (Staff)
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+xI have made a mixture and it's been drying for 24 hours, however its still tacky, im assuming I have not used enough hardner? Sorry Martin, I forgot to add an answer on this last question; if you have resin that's still not cured after 24hrs and you would like to know if there's a problem then we'll need a little more information on what resin you're using and what your cure environment is like. You mention a 100:30 mix ratio so you're most likely to be using our EL2 laminating epoxy or IN2 infusion epoxy but we also have a choice of hardener speeds on those systems too. Please confirm what resin and hardener you're using and also what the ambient cure temperature is (for the whole cure time) and I'll let you know if you have a problem.
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martynball
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Thanks for that information this has helped! My eproxy mixture has been at room temperature, however, heating has been off, so that can go down to 2 degrees! So I doubt the mixture is correct. It has been about 48 hours at least now. I will try another mixture and start again  They where only small 1CM by 0.5CM stickers anyway.
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Matt (Staff)
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+xThanks for that information this has helped! My eproxy mixture has been at room temperature, however, heating has been off, so that can go down to 2 degrees! So I doubt the mixture is correct. It has been about 48 hours at least now. I will try another mixture and start again They where only small 1CM by 0.5CM stickers anyway. OK but what resin and what hardener speed were you using? - Also, an ambient temperature that could have gone down to 2'C would certainly stall the reaction - at this temperature the resin would stay uncured for months. If you're using the IN2 resin (for example) with a slow hardener then that would take more than 48hrs to cure at 15'C so it still might be OK, just in desperate need of some warm curing conditions.
Matt StathamEasy Composites / Carbon Mods - Technical Sales
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GreyArea
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Just a minor quibble. It’s great that you stick to parts by weight. But then you provide syringes for things like the MEKP hardener, which of course dispense by volume.
I know...could always use the syringe to withdraw a volume then weigh it...but that kind of defeats the object of having the syring in the first place in that we need a very accurate balance for such small quantities. Also, your syringes are really, really poor (sorry but they are) in that the action is not at all smooth so you end up with a kind of “all or nothing” dispenser.
I don’t believe in having a whinge without suggesting a solution...so have you thought about pipettes instead? You can get one piece plastic ones with bulbs these days, or go down the glass and separately bulb route if the materials might dissolve plastic. They won’t be graduated of course, but as mentioned above, if you always specify addition by weight that doesn’t matter - unless you can furnish us with a list of product specific gravities?
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martynball
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+x+xThanks for that information this has helped! My eproxy mixture has been at room temperature, however, heating has been off, so that can go down to 2 degrees! So I doubt the mixture is correct. It has been about 48 hours at least now. I will try another mixture and start again They where only small 1CM by 0.5CM stickers anyway. OK but what resin and what hardener speed were you using? - Also, an ambient temperature that could have gone down to 2'C would certainly stall the reaction - at this temperature the resin would stay uncured for months. If you're using the IN2 resin (for example) with a slow hardener then that would take more than 48hrs to cure at 15'C so it still might be OK, just in desperate need of some warm curing conditions. Using your EL2 Laminating EProxy. The ambient temperature may not get that low to be honest, however today it was -2'C outside and the heating hasn't been on most of the day whilst we where all at work, so it would have been pretty cold. I will make another mixture and make some more but leave the ones I have made to one side see if they cure, I keep on touching one of them and it's still pretty tacky.
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oekmont
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+x[quote]Just a minor quibble. It’s great that you stick to parts by weight. But then you provide syringes for things like the MEKP hardener, which of course dispense by volume.
Ec
Exactly. The important point here is "for mekp". Unlike epoxy "hardener" mekp is actually a hardener. The final structure of solid polyester is solely build of the resin component, mekp just starts the reaction. Therefore you can slightly change the mekp ratio, wich will affect the curing time. Anything between 1,5 and 2,5 % should be fine.
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David Vale
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I have constructed a 'warming cabinet' out of Celotex (could use Kingspan or anything similar. The smallest oil filled radiator from Machine Mart with a thermostatic control works just fine in my unheated workshop. At UK current ambient temperatures nothing is going to cure. For smaller parts a cheap Dunelm electric blanket and an airing cupboard raided duvet works really well too. It is not difficult to keep the temperature in the mid 20's, don't go too high though as the PVC vac tube just collapses.
On the subject of weight versus volume, what are the densities of IN2 and hardener. I have been using accurate paint shop measuring beakers and they seem just fine. MEKP a catalyst and just activates resin as opposed to IN2 and hardener where both constituents react together to create a solid resin.
Retired - Thank heavens, and still don't have enough time during the day
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