I've noticed on a few test pieces i have created that the face touching the mould / surface is lovely smooth, flat, perfectly cured, however the face open to the air is still tacky especially when in contact with sweat from hands / slight dampness in any way.

I'm quite confident i've got the ratios correct, i've used two separate scales, the second more accurate than the first, and mixed thoroughly - i mix in a mixing pot with a wooden spatula for 3+ mins or so, yet it still comes out this tacky / cracked looking way. 

I have tried post-curing the piece in an oven, however this hasnt got rid of the tackiness and has exacerbated the "cracked" look. See attached picture for the piece from the oven, however i assure this is how my other pieces have looked also, just less-so.

Could anyone give me some advice on where i'm going wrong ? I've done enough playing and want to start seriously making some working prototypes but i cant seem to work out what the problem is here. In the attached photo i was hoping for that nice, shiney, stereotypical carbon fibre look but uhh....not so...  

Thanks, J.

Is it only on the back surface?  Generally in our experience the only way a resin can cure in different ways in different places (assuming all other factors are the same) is through mixing issues.  If it is always the back face which is the last bit to be laminated, then I would think that you would be getting to the end of the resin in your pot as well so if the resin has not been fully mixed by scraping around the edges or bottom of the cup, so when you do the last bit, the resin you use might not be as fully mixed as the rest. 

You can try more thorough mixing and also what sometimes helps is to pour the  mixed resin into a clean cup and mix again for a couple of minutes.

The fact that heat hasn't got rid of it means that  the poorly mixed bits are a bit too far out for the heat to force the cure.


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

Let us know how you get on.


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant