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Massimiliano
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Hello,
what are the ways to extend the pot life of polyester resin (if possible)?
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oekmont
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Group: Forum Members
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There are three options: 1:Temperature this is really only an option if you are working at a hot place. Try to work early, when temperature is still low (you should be at a very well ventilated place anyways) 2:mekp ratio: most resins need 2% on paper, but usually you can get a little higher of lower (1-2,5%). However, you should try out if your resin still fully cures at lower percentages than recommended. There are slower hardener types than mekp, but it is hard to get them as a hobbyist. 3:inhibitor. Again, it may be hard to get your hand on, but it is by far the easiest and most comfortable option to extend the pot life of polyester resins. Use the recommended mekp ratio and add a small amount of inhibitor to mix. You can easily double or quadruple the pot life of polyester resins (depending on the inhibitor percentage) without worrying about a full cure. As far as I know EC doesn't sell this (If someone is reading: you should try to add this to your shop, I am a great fan of this). I get mine at https://www.phd-24.de/harze/polyesterharz/verzoegerer-inhibitor
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Hanaldo
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Group: Forum Members
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The trouble with inhibitors is not all polyesters/vinyl esters react equally. I can actually get TBC inhibitor locally, but the polyester resin I get from the same supplier does not respond well to it. It has virtually zero effect on the pot-life, but has a massive effect on how fast the resin kicks once it has begun to gel.
On the other hand, it works well with the vinyl I get from that supplier.
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oekmont
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Group: Forum Members
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I never had any problems. It worked just as intended with about 15 different polyester resins. Never tried it with vinyl, because I only have the two vinyl components of the unimould system and those aren't that fast anyways.
Maybe I should be careful in the future.
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Massimiliano
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Group: Forum Members
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+xThere are three options: 1:Temperature this is really only an option if you are working at a hot place. Try to work early, when temperature is still low (you should be at a very well ventilated place anyways) 2:mekp ratio: most resins need 2% on paper, but usually you can get a little higher of lower (1-2,5%). However, you should try out if your resin still fully cures at lower percentages than recommended. There are slower hardener types than mekp, but it is hard to get them as a hobbyist. 3:inhibitor. Again, it may be hard to get your hand on, but it is by far the easiest and most comfortable option to extend the pot life of polyester resins. Use the recommended mekp ratio and add a small amount of inhibitor to mix. You can easily double or quadruple the pot life of polyester resins (depending on the inhibitor percentage) without worrying about a full cure. As far as I know EC doesn't sell this (If someone is reading: you should try to add this to your shop, I am a great fan of this). I get mine at https://www.phd-24.de/harze/polyesterharz/verzoegerer-inhibitor Thank you so so much!! I am still too slow in laminating, was thinking about getting rid of polyester and switch to epoxy.... hope this product will build confidence!
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Massimiliano
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Group: Forum Members
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+xI never had any problems. It worked just as intended with about 15 different polyester resins. Never tried it with vinyl, because I only have the two vinyl components of the unimould system and those aren't that fast anyways. Maybe I should be careful in the future. I found the coupling coat too fast... I would say 10-12 mins and it starts gelling. Last time I used it has been a nightmare
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Hanaldo
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Epoxy is harder to hand laminate with than polyester, for sure.
It sounds like you are mixing your batches too big? Only mix what you can use within the pot-life. As you get experience, you will learn to work faster and be able to mix larger batches. I started off struggling to get 500g on the job before it started to gel. These days I have no worries mixing 2kg on a 40° day and getting it all on in 5 minutes. But start slow, give yourself more time by doing more mixing.
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Massimiliano
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Group: Forum Members
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+xEpoxy is harder to hand laminate with than polyester, for sure. It sounds like you are mixing your batches too big? Only mix what you can use within the pot-life. As you get experience, you will learn to work faster and be able to mix larger batches. I started off struggling to get 500g on the job before it started to gel. These days I have no worries mixing 2kg on a 40° day and getting it all on in 5 minutes. But start slow, give yourself more time by doing more mixing. 2kgs in 5 mins? How many arms do you have? :-)) You are right... I need more practice with smaller parts and especially smaller batches. What is your preferred tool to spread the resin? Brush, roller, squeegee etc.?
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Chris Rogers
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Some people use a MEKP/CHP blend as a summer blend for hot weather - to stretch out the gel time and not have it go off so fast/hot. I think Norox MCP-75 is this... not my area of expertise. Not sure if it would work for a polyester for open molding with standard promoters but Norox MEKP 925 H or similar catalysts have less peroxide and will give a longer gel time and lower viscosity before gel but still hit it hard for a complete cure. I understand it works for infusion with VE but maybe the wrong match here so don't take my word for it!
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