Hi All,

I'm a beginner in Composite World.

I created a mould from a bonnet from a reacecar.


So far, so good.

Next step was to create a carbon fibre bonnet.
First I used several coats of easy lease Chemical Release agent on the mould.
Then, I did one layer of GC50 Epoxy Compatible Gelcoat. I used 2% MEKP hardener, maybe a little more.
Then, I did One layer of 200gr Carbon Fibre, 2mm Lantor Soric core material, and then again a layer of 200gr Carbon Fibre.



Next was all necessary thing for vacuum bagging., as shown below;.



The day after I removed the peel ply, and took the bonnet out of the mould.



But then I saw the GC50 did not stick to the EL160 resin. I could peel it all off !!



Which resulted in this on the floor !







this leave me with a bonnet with a very wavy surface !





Question1 : What did I do wrong?
Question2 : How can I repair this?

Thanks,

Gerry.

What was your process?  What sort of temperature were you working at and through the cure?  How soon after the El160 was laid up was it demoulded? Was the part post cured?  How old was your stock of GC50?

A lot of issues around delamination with GC50 can be temperature related or  some kind of contaminant so it is worth finding out your exact process.  Something has gone drastically wrong for it to not stick at all to the extent you can peel it off!!


Repair  is going to be with a coating resin such as our XCR Epoxy Coating Resin as it will form a nice even layer and can be easily sanded smooth and re-polished to a gloss.  Ensure the surface of the bonnet has a real good key and has been thoroughly decontaminated before coating with resin.  You may need to do a couple of coats depending how rough it is.  Once cured, sand it smooth and finish off just like you would when skinning a part.



Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

Thanks for your answer.

The temp was between 11 and 15 degrees Celcius. Yes this is a little bit cold. I know. Can this make such a mess?

I used the EL160 the day after I used the SC50. The layer of SC50 was hard. (just like I saw in your instructional movie on YouTube). So I don't think that caused the peeling. Please correct me if I'm wrong.

Laying down all the layers and applying the resin took me 2 hours. Then I applied vacuum for about 7 hours. After that I left it in the mould an extra 20 hours, without vacuum. So the next day I demoulded it. Eveything was hard. No resin was sticky.

The part was not post cured.

The SC50 was 3 weeks old.

For the part of the repair:
1. Sorry for my bad English, what do you mean with " the surface has to have a real good key? I do not understand this.
2. The decontamination-part : is it ok to clean the surface with grease-remover?
3. Do I have to sand it before applying the XCR, so it sticks better. If yes, which grain of sanding paper do I have to use? more like P100 of finer ? Like P400?

Thanks !

Gerry.

Its either the cold that has effected the bond strength or not leaving it long enough before demoulding.  EL160 needs a minimum of 24 hours at 25C and your temperature was considerably below that.  Demoulding green can effect bond to GC50 as can generally cold conditions. So it could be a bit of both.

Leaving GC50 over night  is typical so i doubt that was an issue .

Giving the surface a key is sanding the surface.  240 grit will be fine, just ensure you don't sand too far  and break into the carbon ruining the weave pattern.


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

For anybody who wants to know how it turned out : Is was OK.

See this google photoalbum for the full story so far.

Thanks Easy Composites, thanks Warren.

Gerry.

Hi GeeDee,  glad it all turned out ok in the end.


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant