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okkim
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Hi, I have searched a lot, but I can't find a clear answer to my case. I am making moulds for the carbon fiber fenders. The moulds are almost ready and I started to wonder if I need to post cure them? They are made from vinylester gelcoat, and polyester resin with fiberglass. If I need to post cure the moulds, how should I do it and do I need to leave the original fender inside the mould while doing it? And the same applies to curing the parts. I will make the parts from carbon fiber and epoxy using infusion. How those should be cured? Parts inside the moulds or not? I will use this resin: https://composite24.co.uk/infusion-epoxy-resin-1-5kgAlso, how much resin I need? I am guessing that 1.5 kg/fender? 
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Steve Broad
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+xHi, I have searched a lot, but I can't find a clear answer to my case. I am making moulds for the carbon fiber fenders. The moulds are almost ready and I started to wonder if I need to post cure them? They are made from vinylester gelcoat, and polyester resin with fiberglass. If I need to post cure the moulds, how should I do it and do I need to leave the original fender inside the mould while doing it? And the same applies to curing the parts. I will make the parts from carbon fiber and epoxy using infusion. How those should be cured? Parts inside the moulds or not? I will use this resin: https://composite24.co.uk/infusion-epoxy-resin-1-5kgAlso, how much resin I need? I am guessing that 1.5 kg/fender? If using resin infusion then I wouldn't bother as very little heat is involved in the curing process.
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Warren (Staff)
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Although Steve is technically correct, sometimes it is nice to be able to post cure carbon car panels to help avoid any softening when first exposed to a hot sunny day. Although in most climates, at worst you might get a little bit of fibre print from such sun exposure, it can be beneficial to post cure it anyway. If you choose to do so, you would want to post cure the mould as well before use.
Generally for parts where there is likely a lag in time between making and fitting of a few weeks, its unlikely to be a major issue. However very hot/sunny climates and brand new fresh parts can cause a few issues with print when the part softens slightly on first exposure to the suns heat.
Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant
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okkim
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Thanks for the reply! I could cure the parts in the sauna  , but I would like to use 3 kW infrared heater if that is sufficient? And do I need to rise temperature gradually, or can I heat it straight to (For example) 50C? And does the temperature need to go down slowly too?
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Steve Broad
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Group: Forum Members
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+xAlthough Steve is technically correct, sometimes it is nice to be able to post cure carbon car panels to help avoid any softening when first exposed to a hot sunny day. Although in most climates, at worst you might get a little bit of fibre print from such sun exposure, it can be beneficial to post cure it anyway. If you choose to do so, you would want to post cure the mould as well before use. Generally for parts where there is likely a lag in time between making and fitting of a few weeks, its unlikely to be a major issue. However very hot/sunny climates and brand new fresh parts can cause a few issues with print when the part softens slightly on first exposure to the suns heat. The OP was asking about post curing the moulds, not the items :-) Post curing the carbon parts is a good idea if there is any chance of them being exposed to the sun for long periods, as you say. If using standard epoxy resin, I am guessing that the max temp you can post cure to is around 80 deg C ? Post curing carbon needs to be done in accordance to the manufacturers instructions. This tends to be an increase of around 0.3 deg C per minute, which is pretty slow. Whether this is important I have no idea, but I am sure Warren does.
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Hanaldo
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+x+xAlthough Steve is technically correct, sometimes it is nice to be able to post cure carbon car panels to help avoid any softening when first exposed to a hot sunny day. Although in most climates, at worst you might get a little bit of fibre print from such sun exposure, it can be beneficial to post cure it anyway. If you choose to do so, you would want to post cure the mould as well before use. Generally for parts where there is likely a lag in time between making and fitting of a few weeks, its unlikely to be a major issue. However very hot/sunny climates and brand new fresh parts can cause a few issues with print when the part softens slightly on first exposure to the suns heat. The OP was asking about post curing the moulds, not the items :-) Post curing the carbon parts is a good idea if there is any chance of them being exposed to the sun for long periods, as you say. If using standard epoxy resin, I am guessing that the max temp you can post cure to is around 80 deg C ? Post curing carbon needs to be done in accordance to the manufacturers instructions. This tends to be an increase of around 0.3 deg C per minute, which is pretty slow. Whether this is important I have no idea, but I am sure Warren does. I'm sure Warren understood the OP's question, but it is always better to post-cure the carbon part BEFORE demoulding; in which case the mould also needs post curing prior to making the part. When post-curing prior to demoulding for both the mould and the final component, ramp rate is less critical and you can go straight to 50C.
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okkim
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I was talking of curing both, the mould and then later the actual part. I can't find good data sheet for the epoxy resin, but in the web page photo in the bottle is short guide. So If I read it correctly first 24 hours curing in the mould, then two hours at 60-80C. So I guess I have to bring the parts to my sauna 
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Hanaldo
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I'd post-cure it for longer than that. Maybe 2 hours at 80 is ok, but generally at 60 you're looking at 12 hours minimum. The longer the better anyway. Leave it overnight if you can, but make sure that it is supported so that it sits in the correct shape - if it sits crooked and gets post-cured, then the shape will stay that way forever.
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okkim
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Ok, thanks! I will do that.
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Steve Broad
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Group: Forum Members
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+x+x+xAlthough Steve is technically correct, sometimes it is nice to be able to post cure carbon car panels to help avoid any softening when first exposed to a hot sunny day. Although in most climates, at worst you might get a little bit of fibre print from such sun exposure, it can be beneficial to post cure it anyway. If you choose to do so, you would want to post cure the mould as well before use. Generally for parts where there is likely a lag in time between making and fitting of a few weeks, its unlikely to be a major issue. However very hot/sunny climates and brand new fresh parts can cause a few issues with print when the part softens slightly on first exposure to the suns heat. The OP was asking about post curing the moulds, not the items :-) Post curing the carbon parts is a good idea if there is any chance of them being exposed to the sun for long periods, as you say. If using standard epoxy resin, I am guessing that the max temp you can post cure to is around 80 deg C ? Post curing carbon needs to be done in accordance to the manufacturers instructions. This tends to be an increase of around 0.3 deg C per minute, which is pretty slow. Whether this is important I have no idea, but I am sure Warren does. I'm sure Warren understood the OP's question, but it is always better to post-cure the carbon part BEFORE demoulding; in which case the mould also needs post curing prior to making the part. When post-curing prior to demoulding for both the mould and the final component, ramp rate is less critical and you can go straight to 50C. Of course, keep forgetting that we aren't talking prepreg here.
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