Talk Composites - The Forum for Advanced Composites

Having issues with XCR Base Coat for Carbon Skinning

http://www.talkcomposites.com/Topic25700.aspx

By BMac - 4/12/2018 3:12:07 PM

Hi,

I have two long car parts made from ABS plastic roughly 2.2 meters long.
My first attempt of carbon skinning was not too bad.  The biggest problem i had was getting the Carbon Fiber cloth to stick to the part in tight 90 degree corners etc.  I also found that the Normal Best Seller 2x2 Twill weave cloth was very unforgiving.  I got a lot of distortions and fraying. too easily.

I have sanded down the products as i didn'twant to waste over 100 pounds worth of clear resin only to not like the distortions.

To start over i am going to order the Pro-Finish Carbon Fiber as it states it has a resin backing to prevent distorting and hope it will be more forgiving.

I do have a question regarding the XCR Base Coat.  I roughly sanded the plastic product with 120 grit and deeply scored it all over criss crossing with a Razor blade leaving a rough surface.  But at 90 degree angles i found the cloth lifting causing a bubble and at the edges of the product there where parts where it separated from the plastic.  This resulted in gaps (1mm or so) between the plastic and cloth.

I followed the instructions and kept checking the base coat until the resin did not lift off the product onto my finger but was still very tacky.  Is there a more sticky version available?  Can i use the spray on adhesive when i see it separating from the edges or will this react with the resin?  Do i wait until the base coat is totally dry and then use spray on adhesive or if it is not possible inject glue into the bubbles at the angles and cement them back down?

Does anyone have any recommendations?
By BMac - 4/13/2018 11:53:44 AM

 
Warren (Staff) - 4/13/2018 8:20:06 AM
There isn't really anything more sticky as such than the basecoat.  You will find that if you use a spray tack, often the glue will begin to loose it's hold as you wet the fabric out with resin.

What you can do on tight corners is to place the fabric where it needs to be then leave the clear coating resin for another few hours time. It will give the basecoat a bit more time to set and grip the fabric a bit better.  If that doesnt work you can use a small plastic or similar former the same shape as the corner to press the fabric into the corner then leave it there while the basecoat sets.   Release coat the former or use a bit of polypropylene sheeting or packing tape on it so it does not stick to any resin that squeezes through the fabric.

Thanks. I was thinking of using wooden planks and g clamps on the areas where it was lifting. Covering the wood with packing tape is a good call. Could just see me lifting the planks off and the fabric fraying again. Arghhhhh!.

Ome more thing. Because the side skirt is so long I found sometimes I had to re lift some parts of the fabric. It was a mess no matter how careful I was. Would it help to use a heat gun when this happens?

Thanks for the advice