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Philippine
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Hi, I am currently making carbon fibre samples of different layers and using different methods. I have managed to get a really good surface finish with hand lay-up but not with infusion (photo attached). I saw someone post a similar question on the forum but he was using unidirectional so our problem might be different.  Following the videos you've made for infusion, the surface finish of all may samples are almost entirely dry as if there wasn't enough resin. You've suggested to reduced the flow speed to allow the resin to get everywhere which I will try very soon. However, my samples are pretty small (210x160mm) and I'm worried that it won't be enough. Could the infusion spiral be completely removed to allow a slower flow process ? Any advice would be greatly appreciated! Many thanks, Philippine
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Hanaldo
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Yeh, it's just not enough resin. And given the size of your samples, that's not surprising - infusing small pieces with proper infusion resin can be tricky, as the resin often just flows super quick over the back and doesnt have time to wet out the surface properly. With bigger infusions this solves itself as the resin doesnt flow as quickly, but with smaller infusions it can be helpful to use a higher viscosity resin (max 550cps), or just use a hose clamp to throttle the flow to about an inch per minute.
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Philippine
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Group: Forum Members
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+xYeh, it's just not enough resin. And given the size of your samples, that's not surprising - infusing small pieces with proper infusion resin can be tricky, as the resin often just flows super quick over the back and doesnt have time to wet out the surface properly. With bigger infusions this solves itself as the resin doesnt flow as quickly, but with smaller infusions it can be helpful to use a higher viscosity resin (max 550cps), or just use a hose clamp to throttle the flow to about an inch per minute. Thank you very much for your answer. I tried it yesterday and demoulded it this morning and the resin still hasn't filled all the cloth. Should I keep the pump running when the resin is flowing on the panel or should I stop it ? I might try hand lay-up followed by vacuum bagging tomorrow. Hopefully that should work.
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MarkMK
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When the resin has reached the exit port and everything appears to have wet through, close the exit but leave the inlet side open for a couple of minutes. This should allow enough time for the resin to completely fill the part On such a small sample, you can likely get away with using no spiral and a narrow strip of flow mesh at the inlet side should be enough. On larger pieces, it's common to cut any flow mesh just before the exit line (about an inch or so) and this helps to slow things down and allow time for the resin to flow to all areas before starting to flow up the exit line. Another narrow strip under your exit port will help to evacuate any air in the resin as it reaches the end of the part. So, a narrow strip at the resin feed side, with another strip at the exit should leave enough of a space inbetween to allow for a slow and thorough wetting-out of your part and, hopefully, no dry spots when cured
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Dromilious
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+xHi, I am currently making carbon fibre samples of different layers and using different methods. I have managed to get a really good surface finish with hand lay-up but not with infusion (photo attached). I saw someone post a similar question on the forum but he was using unidirectional so our problem might be different. Following the videos you've made for infusion, the surface finish of all may samples are almost entirely dry as if there wasn't enough resin. You've suggested to reduced the flow speed to allow the resin to get everywhere which I will try very soon. However, my samples are pretty small (210x160mm) and I'm worried that it won't be enough. Could the infusion spiral be completely removed to allow a slower flow process ? Any advice would be greatly appreciated! Many thanks, Philippine Hello.maybe you have seen my post.i had dry spots and this caused by the unidirectional fibre.now i infuse a bigger part and i use the same amount of resin i used in the smaller and i have again some dry spots.i think it is poor of resin.i will add 30 grams . I think you have the same occasion. I suggest you close the vacuum line and let 1 minute or less the feed line to make it rich.
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Philippine
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Group: Forum Members
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I have tried again removing the spiral line and only putting two thin strips of mesh. I've also closed the vacuum pump line and let the resin flow for a while. It took almost an hour to fill the entire panel. Maybe it wasn't quick enough this time. It still didn't work, I must be doing something wrong but don't know what anymore.
I've start with vacuum bagging tomorrow as it should give the same properties more or less. Hopefully, that will work.
Thank you all for your answers!
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dcfoster
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Im having a similar issue, but its also leaving some of the epoxy on the mold surface. Ive added mesh to increase flow upon entry and created a resin break to slow down exiting epoxy into the catch pot. Also im using an infusion epoxy yet I keep getting dry patches. Im using a blue carbon/nylon cloth for the visible layer and then a +/- 45 biax for the underlayer. This is for a fuel door for an Acura. Ive never had this issue before, even with small parts but I keep getting it with this. Could it be since its winter that its too cold? I made sure to put my epoxy in front of a heat source to warm it up and noticed it gassed alot less when mixing, I also let it sit to degass for the 15min I usually wait to make sure the infusion molding is properly sealed and not leaking (the epoxy I use has a long pot life). Yet it only made less dry spots but still have them. Pics included. Original poster. sorry to thread jack, figured since you already have a thread open it just makes sense to keep all the 'dry fiber' issues in one thread.
 
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Dromilious
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Group: Forum Members
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+xIm having a similar issue, but its also leaving some of the epoxy on the mold surface. Ive added mesh to increase flow upon entry and created a resin break to slow down exiting epoxy into the catch pot. Also im using an infusion epoxy yet I keep getting dry patches. Im using a blue carbon/nylon cloth for the visible layer and then a +/- 45 biax for the underlayer. This is for a fuel door for an Acura. Ive never had this issue before, even with small parts but I keep getting it with this. Could it be since its winter that its too cold? I made sure to put my epoxy in front of a heat source to warm it up and noticed it gassed alot less when mixing, I also let it sit to degass for the 15min I usually wait to make sure the infusion molding is properly sealed and not leaking (the epoxy I use has a long pot life). Yet it only made less dry spots but still have them. Pics included. Original poster. sorry to thread jack, figured since you already have a thread open it just makes sense to keep all the 'dry fiber' issues in one thread.
I had a problem like that once .I think you didn't have enough release wax on the mold.
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Lester Populaire
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+xIm having a similar issue, but its also leaving some of the epoxy on the mold surface. Ive added mesh to increase flow upon entry and created a resin break to slow down exiting epoxy into the catch pot. Also im using an infusion epoxy yet I keep getting dry patches. Im using a blue carbon/nylon cloth for the visible layer and then a +/- 45 biax for the underlayer. This is for a fuel door for an Acura. Ive never had this issue before, even with small parts but I keep getting it with this. Could it be since its winter that its too cold? I made sure to put my epoxy in front of a heat source to warm it up and noticed it gassed alot less when mixing, I also let it sit to degass for the 15min I usually wait to make sure the infusion molding is properly sealed and not leaking (the epoxy I use has a long pot life). Yet it only made less dry spots but still have them. Pics included. Original poster. sorry to thread jack, figured since you already have a thread open it just makes sense to keep all the 'dry fiber' issues in one thread.
I would guess it's related to the spray tack. Either too much or a kind that does not dissolve properly in epoxy. To the original poster - could you share a picture of the vacuum setup? Normally this kind of things can be solved with the right infusion setup...
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Dromilious
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Group: Forum Members
Posts: 15,
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+x+xIm having a similar issue, but its also leaving some of the epoxy on the mold surface. Ive added mesh to increase flow upon entry and created a resin break to slow down exiting epoxy into the catch pot. Also im using an infusion epoxy yet I keep getting dry patches. Im using a blue carbon/nylon cloth for the visible layer and then a +/- 45 biax for the underlayer. This is for a fuel door for an Acura. Ive never had this issue before, even with small parts but I keep getting it with this. Could it be since its winter that its too cold? I made sure to put my epoxy in front of a heat source to warm it up and noticed it gassed alot less when mixing, I also let it sit to degass for the 15min I usually wait to make sure the infusion molding is properly sealed and not leaking (the epoxy I use has a long pot life). Yet it only made less dry spots but still have them. Pics included. Original poster. sorry to thread jack, figured since you already have a thread open it just makes sense to keep all the 'dry fiber' issues in one thread.
I would guess it's related to the spray tack. Either too much or a kind that does not dissolve properly in epoxy. To the original poster - could you share a picture of the vacuum setup? Normally this kind of things can be solved with the right infusion setup... i don't think it is from the spray tack. I don't use spray tack and i had once the same problem.
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