Peel ply both on top and bottom?

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#1

We use 2" construction foam glued side by side to make positive molds. It requires a good bit of sanding and bondo to make a decent surface and even then release agents still wont let it come off easily.

If I laid peel ply over the mold, did my layers of carbon fiber, and followed it with a top layer of peel ply do you think it would release well from the mold?
That mold and all would be in the vac bag.

Hoping to cut down on work required on the mold with the hassle of bondo.

Other suggestions?

#2

I am not getting it completely. Can you explain your current process in more words (or perhaps some pictures)

Peelply has a misleading name. It does not help peel things off in any way.

#3

Body fillers have a propensity towards sticking, even with release agent on them. Sounds like you need to use a release film (even a layer of bagging film would work) over the mold. Another option that might help would be to coat the body filler with mold release wax and leave it on rather than buffing it off.

#4

My understanding is that peel ply is a ‘release film’ that prevents the resin from sticking to the vacuum bag and can be peeled off afterwards.

I have been told that we would spend countless hours shaving our foam mold and then coat it with bondo (which requires lots of sanding) to create our final mold.

We then coat our bondo-covered foam mold with release wax (I was told they REALLY coated it) and still had issues in the past of it releasing without tearing off bondo and foam chunks.

I was looking to skip the bondo part and put a release film on top of the construction foam(its a positive mold), then my carbon fiber, and then more release film.

Sorry if my description is terrible. I volunteered to take over body panel construction and expected more help than what I am getting. Kind of scrambling for information! Thanks for the replies.

#5

[ame=“http://www.youtube.com/watch?v=ZltVTZkzIuY”]http://www.youtube.com/watch?v=ZltVTZkzIuY[/ame]

Approximately 6:40 in the video is where he explains peel ply. In a later video it shows him peeling it off after vacuuming is complete.

Hopefully I am coming off a bit more clear. I am a complete noob and only have assisted in wet-layup before.

#6

What he told was that the peelply helped creating a sort of fair surface, with a texture which helps secondary bonding.

And that is about the ONLY function of peelply: create a textured surface for secondary bonding.

But let’s take one step back. What kind of structure are you trying to make? I understand it has something to do with bodywork. (of a car?)

If it is one-off construction, consider the following:

-CNC route a negative mould, in a hard foam. Vacuum a flexible vacuum film, such as SL200 or a PVA film into the mould. This is your mould surface. PVA needs no waxing, SL200 could benefit from a coat of wax or PVA.

In this mould (keep the vacuum) you can create your bodywork. It does need some sanding afterwards, depending on the foam, but for the rest it is clean, cheap, simple.

The laminate stack for your part would be:
laminate
peelply on areas where there is secondary bonding
perforated film (P3 or P31 perforated, not too much perfs)
bleeder
vacuum film

Pull about 15 Hg vacuum.

This is a nice starting point.

#7

Good info! Glad you cleared up the peel ply thing for me.

I dont think we have the time or resources to do a negative CNC mold. Otherwise I would have liked to do infusion.

We are creating body panels for a Mini-baja(off-road buggy) racecar. Here is an picture of last year’s car.

This year we wont be doing a bunch of little triangles and doing the entire side of the car as one panel, nose as one panel, and other side as one panel. The mold will be approximately 3ft long, 1.5 ft wide, and 8 or 9 inches deep.

Here is a picture of a nosecone for a different application, but we create our molds the same way.

I imagined the stackup to be:
vacuum film underneath (bottom layer on the workspace)
The mold
Release film
Layers of carbon fiber
Release film
vacuum film over top

All sealed within the vacuum.
I appreciate all the info!

#8

Ever try peeling off flow media without peel ply? :stuck_out_tongue:
Perf film is nice, but expensive for most people. peel ply helps pull all top consumables off most of the time.

#9

Perf film is cheaper than peelply…

#10

Spray silicone over the foam plug if you can get the foam plug perfect and can play with tolerances. There are plenty of products available.