number 1 is gr8 as an option ,u dont have to go through the headeack of removing it, conside it as a great primer ,u may use the black base coat i think it will show nothing like metal below , hope this is fruitfull

bye

best regards mhd alghoul mhdghoul@hotmail.com youtube channel :atmospherejo link is http://www.youtube.com/user/atmospherejo?ob=0&feature=results_main

Thanks Matt

Epoxy bonds to epoxy when the epoxy you're bonding to is in the 'B' stage of its cure; this allows the fresh epoxy to cross link to the 'B' stage cured epoxy and make a strong chemical bond. Once the first layer of epoxy has fully cured, the cross linking won't happen and the new epoxy will only be able to make a mechanical bond to the first layer of epoxy which is less strong so, although it bonds well (given the appropriate surface preparation/key) it won't be as strong as a bond to 'tacky' (b stage) epoxy.

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

Hi Marc,

OK, yes, that's an unfortunate lesson you've learned there which is that a single layer of carbon laid over something (particularly something bright like bare metal) will show through the original part. What I would suggest you do now is to remove the skin completely with a power sander and start again. Black Epoxy Basecoat is a good idea because epoxy bonds famously well to bare metal. You could use black paint but that bond wouldn't be as good as the epoxy basecoat would be and so it would create an unlikely, but possible, failure point. This failure point would only be likely to be evident if the metal part became hot and expanded (which the carbon skin would not) which puts a lot of stress on the bond line.

All the best, Matt

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

I've just skinned a bare metal bonnet with 1 layer of 200gm plain weave CF, unfortunately I can now see lines of the silvery bonnet through the weave of the CF. I did not apply a black pigmented coat of epoxy on the bonnet prior to laying on the CF because that makes the CF very hard to place perfectly due to it's tackiness. I'm wondering what is the best way to proceed....

You're welcome. i'll second what Kevin says, I don't think etching would be neccessary, a mechanical 'key' and a clean, degreased surface are the priority.

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

Thanks, Matt and Kevin-lee.

Pedro

Hi,

You would not need to etch the metal because epoxy will form an ionic bond with the bonding surface... This is the very reason epoxy exhibits superior adhesion to most materials/substrates and also the very reason that epoxy primers/paints are recommended for "direct to substrate" application... The most important factor would be that the surface is clean and residual free, a key with a scotchbrite also wouldn't hurt...

Kev.

etch the metal