By martynball - 11/29/2017 10:17:46 PM
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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By Hanaldo - 12/15/2017 10:44:23 PM
MEKP also happens to have a specific gravity close to 1, so it is accurate enough to measure by weight or volume.
This may be the case with some epoxy resins, the specific gravities of one or both of their components may happen to be close to 1 as well, which is why you might get away with measuring by volume for some products. I can assure you this isn't the case for all epoxies, and in fact the way epoxies work mean that going off ratio doesn't necessarily mean the product won't cure hard to the touch, but rather it won't achieve its quoted mechanical properties. All well and good for cosmetic parts that just need to be hard and shiny, but for parts that need to perform mechanically - be accurate with the mix.
I met a man once, a chemist who was far cleverer than me. He knew how to manipulate epoxies to give it properties that he wanted, not just make it achieve what it was designed to do. He used to use an entry level epoxy, very similar to West System, and by going off ratio and using hardeners from different resin systems, he was able to make products like bullet proof sheeting from just a solid block of resin, no reinforcement. There's a company here that bought his recipe and is now using it to produce bullet proof windows and intrusion panels for the military. He even claimed to have come up with a mix that was 100% UV stable and would never yellow, though I never personally saw that product and remain a bit skeptical despite knowing how clever he was. Unfortunately he passed away last year and took all that knowledge with him.
Anyway, unless you are an experimental chemist who knows how to combine bisphenols and amines to get a material that does what you want - read the instructions and stick to them!
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