Getting air bubbles and milky residue

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Getting air bubbles and milky residue

Author	Message
BMac	B BMac posted 6 Years Ago Topic Details
B Group: Forum Members Posts: 14, Visits: 50	Hi. I've been working on carbon fibre skinning on some car parts. Everything had went well until I put two last coats on before I start the fine sanding and polishing on the resin. But this time three are loads of crater like holes in the resin everywhere and quite a lit of air bubbles. The finish also has a white milky residue on the top layer. Is this contamination or an issue with the resin? I did re-use the last paintbrush that was cleaned in paint thinners. Could that be the issue or maybe some water residue on the part? Thanks Barry
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Matthieu Libeert	Matthieu Libeert posted 6 Years Ago Post Details
Group: Forum Members Posts: 955, Visits: 3.4K	+x BMac - 7/23/2018 8:38:01 PM Hi. I've been working on carbon fibre skinning on some car parts. Everything had went well until I put two last coats on before I start the fine sanding and polishing on the resin. But this time three are loads of crater like holes in the resin everywhere and quite a lit of air bubbles. The finish also has a white milky residue on the top layer. Is this contamination or an issue with the resin? I did re-use the last paintbrush that was cleaned in paint thinners. Could that be the issue or maybe some water residue on the part? Thanks Barry pretty sure it is caused by water, you probably wet-sanded? wet sanding on 'uncured' resin will make it go cloudy...keep in mind that epoxy resin only goes into full cure after 7 days sometimes even longer...that"s why postcuring your parts if possible is a good thing to do Matthieu Libeert Founder MAT2 Composites X Sports website: www.mat2composites.com
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BMac	B BMac posted 6 Years Ago Post Details
B Group: Forum Members Posts: 14, Visits: 50	+x Matthieu Libeert - 7/23/2018 10:24:41 PM +x BMac - 7/23/2018 8:38:01 PM Hi. I've been working on carbon fibre skinning on some car parts. Everything had went well until I put two last coats on before I start the fine sanding and polishing on the resin. But this time three are loads of crater like holes in the resin everywhere and quite a lit of air bubbles. The finish also has a white milky residue on the top layer. Is this contamination or an issue with the resin? I did re-use the last paintbrush that was cleaned in paint thinners. Could that be the issue or maybe some water residue on the part? Thanks Barry pretty sure it is caused by water, you probably wet-sanded? wet sanding on 'uncured' resin will make it go cloudy...keep in mind that epoxy resin only goes into full cure after 7 days sometimes even longer...that"s why postcuring your parts if possible is a good thing to do I didn't wet sand it and resin was cured 24 hours. I did wash off the dust using water. Maybe there was a residue somewhere on the part. Would paint thinners on the brush work ok or should I just replace them each time?
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Hanaldo	Hanaldo posted 6 Years Ago Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	Dont use paint thinners, use acetone for cleaning. Or just replace each use. 24 hours is sort of the very minimum cure time for an epoxy, and that's assuming the temperature didn't drop below 25C. Ideally dont expose it to water for 72 hours unless you've done an elevated temperature cure.
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