Has anyone used prepreg to overlay an existing part?
Would the prepreg have enough resin to permanetly stick the cloth to the part?
If this is do-able i would be appling subsequent coats of epoxy to smooth out the texture.
Yep, the 200° cure stuff is sticky as hell. It’s actually so sticky that it’s hard to use if you get the two-sided stuff. It’s like being a fly on flypaper. The single-sided prepreg works like it’s got “Ultra” Super77 on it. Really nice…
double sided and single sided? I thought all prepreg was saturated through evenly?
No, all the diffent prepreg I’ve used has a film of epoxy bonded to either one or both sides. Google single sided prepreg and see the results.
That’s another way people create their own prepregs. They buy rolls of epoxy film and run it under a hot-roller together with their fabric of choice.
you could always use a glue film 
I found only Hysol in my search that sells the epoxy film adhesive.
How much $ does it cost per yard and how wide is the roll? What is the lowest temperature it takes to cure the epoxy film?
About prepreg; Is there not a woven cf prepreg that is equally saturated on both sides? Wouldn’t you want such a prepreg for the first layer into the mold, so you get a nice smooth finish on one side?
I don’t think they have full yards because it looks like the sizing is only 12"x12" but you could get some small pieces from them to test this method out. http://www.mycarbonexpress.com/Prepreg.html
Anyone know at what temperature does the film cure? Most of my overlaid parts are plastic ( abs, ppo, or pe ). Those parts can’t be heated above 120F or they expand to much then when cooled pop goes the cf bond, or the plastic part can warp under oven heat.
Also is there a room temp cure prepreg cf woven twill cloth?
Advanced Vehicle Technology sells epoxy film adhesive. It’s $31/yd and cures at 250°F. The lowest temp I’ve seen for prepreg is 180°F, but I’ve heard of material that liquify at room temp. I guess that suggests that you’d have to work with the material quickly, right out of the freezer.
The double-sided prepreg is “equally saturated” on both sides. With the single-sided stuff, the resin goes against the mold, and it would be best to have that prepreg layer at a higher resin-ratio. I have not found any readily-available prepreg suppliers that think their prepreg will be without surface defects using only vacuum-bagging…
If you are bagging the plastic parts be very careful that no bridging exists in the bag.
Advanced composites group manufacture a material for overlayng components its called LTM26. Word of warning material outlife is only 2 days. M
claren interiors are made by having the oem part made from aluminium with veneer of beech wood over the top to form the substrate which has enough pourosity for the resin to really bond to it.
Hope this helps guys
1: there are low-cure film adhesives, but nothing room temp. Gotta call and ask. Can go anywhere from 150f to 450f.
2: gotta be WAY more specific Fastr, than asking how much a hysol film adhesive costs…there are many
3: singlesided prepreg sucks sometimes, not always. I’ve had both. Some you TOUCH and you loose the glove…some are just fine, unless you forget to use the tacky side on a mold.
4: there are various methods for making prepreg, some just meter resin on one side, some squeeze it through both, some are just a film on one side.
5: some film adh. have a scrim to keep it together!!! That might not work for using it as a surface layer of a show part.