In mould clear coat sinking into fibres?

[TCook]

Bit of a weird issue I’ve come across. I have sprayed a 2k general automotive clear coat into the mould before laying up. Infused it and took out the part and it looked great. However after a day or two it looks as if the clear coat has almost sunk into the fibre gaps giving it a strange texture. I have tried to take photos but it is a very small detail so I hope you can see it. It is all over the part not just in the photoed areas. I have also had the same issue with a polyester gel coat I used previously. The more scratched image is the much thicker gel coat and the less scratched is a much thinner 2k clear coat. 
 

any ideas as to why this is and how to stop it? I could maybe understand if the gel coat one got too hot in the sun or just ambient temps of 25-30°c but I would think the much harder automotive clear coat wouldn’t budge. 

[lo_0l]

On 8/10/2024 at 11:03 AM, TCook said:

Bit of a weird issue I’ve come across. I have sprayed a 2k general automotive clear coat into the mould before laying up. Infused it and took out the part and it looked great. However after a day or two it looks as if the clear coat has almost sunk into the fibre gaps giving it a strange texture. I have tried to take photos but it is a very small detail so I hope you can see it. It is all over the part not just in the photoed areas. I have also had the same issue with a polyester gel coat I used previously. The more scratched image is the much thicker gel coat and the less scratched is a much thinner 2k clear coat. 
 

any ideas as to why this is and how to stop it? I could maybe understand if the gel coat one got too hot in the sun or just ambient temps of 25-30°c but I would think the much harder automotive clear coat wouldn’t budge. 

You sprayed clear coat into the mold and then did the layup?

Usually, you do that after. That might be your problem right there 😄

[TCook]

Done it plenty times before with no issue. The part comes out of the mould perfect then after a few days it will lose its flat/smooth surface. I believe this is due to the part not fully curing when in the mould and then still being slightly malleable before it cures fully. I need to do more testing with curing times in the oven and it should be sorted. 

[lo_0l]

1 hour ago, TCook said:

Done it plenty times before with no issue. The part comes out of the mould perfect then after a few days it will lose its flat/smooth surface. I believe this is due to the part not fully curing when in the mould and then still being slightly malleable before it cures fully. I need to do more testing with curing times in the oven and it should be sorted. 

Sounds like the paint is contaminating the resin/prepreg. Try doing this clear coat during layup, prepping, sanding, and coating.

I'd bet you'll come out with much better parts 👍