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Old 11-09-2017, 03:57 AM   #1
turborav

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Default Poor Surface finish after infusion (pics inc)

Can anyone herlp,

I infused a sheet of carbon this week and the results are shocking. The stack was 2 layers of 200g 2x2 twill. A semi permanent release agent was applied and it was infused with poyester infusion resin mixted with 1ml cat to 100g resin, no gelcoat.

The part held full vac throgh out the infusion and excess resin was allowed into the resin once it was all wetted out.

Then cured at room temp.

Really stumped as to what has gone wrong.

Any ideas?
not sure how to upload an image?
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Old 11-09-2017, 04:05 AM   #2
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here are the pics
Attached Images
File Type: jpg IMG-20171108-WA0003.jpg (246.2 KB, 62 views)
File Type: jpg IMG-20171108-WA0002.jpg (228.6 KB, 47 views)
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Old 11-09-2017, 07:23 PM   #3
Hanaldo

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Looks like typical polyester shrinkage to me. I would suggest leaving it to cure for longer before demoulding, and do an elevated temperature cure on it if you can.

You may find that your release agent is part of the trouble as well. If it is a typical high-slip semi-perm, then the shrinkage of the resin can cause it to lift away from the mould surface while it is curing.
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Old 11-09-2017, 11:48 PM   #4
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I see,
will look into that then, could leaving the vac line on for too long also be a cause? I didnt clamp the vac off for a good while after the resin was shut off. I made the laminate resin rich first then left the vac off, I have a decent resin break so the vac didnt pull any resin out of the stack if that makes sense
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Old 11-10-2017, 02:50 AM   #5
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It doesnt look like a dry laminate from what I can see, it looks well infused. I would wager that if you had done that piece with epoxy, it would be perfect.
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Old 11-10-2017, 03:02 AM   #6
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Quote:
Originally Posted by Hanaldo View Post
It doesnt look like a dry laminate from what I can see, it looks well infused. I would wager that if you had done that piece with epoxy, it would be perfect.
yes it would, but the price of epoxy makes this not a very salable part, I have been getting some really good results but all of a sudden this has happened so just stumped as to what is going on
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Old 11-10-2017, 05:02 PM   #7
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Quote:
Originally Posted by turborav View Post
yes it would, but the price of epoxy makes this not a very salable part, I have been getting some really good results but all of a sudden this has happened so just stumped as to what is going on

Yeh of course, my point was just that this sort of thing isn't the result of something you did 'wrong' in the process. Its more about the materials.

I don't have a lot of experience with infusion polyester and vinyl esters. I tried vinyl ester a few times, but got really poor results like this. For the most part I managed to sort out the shrinkage by allowing it to cure for a week at ambient, then do an elevated temp cure at 50 for 10 hours before demoulding. Then I would remove the bagging material and consumables and leave it for a couple of hours before demoulding to allow excess styrene to escape.

By doing that, I managed to get ok results (although the gloss retention was poor and if I didn't balance the layup schedule I would always experience warpage to some degree). For me, it was such a tedious process that it just wasn't worth it at all, epoxy just works every time. Then of course 5 months later my remaining 15kg of vinyl went off in the drum...

That said, people do use these resins and get good results, so I'm sure with more experience I could have sussed it.
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Old 11-13-2017, 12:40 AM   #8
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Thank, i have done a fair few infusions but just a bit stumped as to why this went wrong, will try again and make it more resin rich, and elevate the heat after 24 hrs. Will report back
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