Having some issues with my first couple of laminations...

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1. I’m still working on getting my resin to composite ratios closer to optimail levels. I think I’m mixing too much resin and the vacuum bagging process is not removing enough of it. However, I think this is just the beginning of my problems. Do you guys weigh out the resin or do you just use experience to guide you?

2. I’ve been using Release Film (Release Bag-125, .001" X 60" Release Film) from FiberGlass Supply as the media between the resin and the breather fabric. However, I pulled the film off this morning and the resin surface is not smooth at all. It’s full of creases. What type of release media should I be using to get a smooth surface on the part I’m trying to laminate? Can I sand resin?

3. How do you eliminate air pockets? I’ve been practicing on clear plexiglass so I can see how well…or poorly…I’ve been applying the wet fabric to the part. I’ve tried with traditional bristle brushes, foam brushes, and a plastic squeegee. I’ve noticed the bristle brush has a tendency to damage the fibers if you’re not careful.

4. Are the steps I’ve been taking correct? This is what I’ve been doing? (1) Mix my resin (US Composites Epoxy Resin + Medium Hardener). (2) I wet my part and wet the fabric. (3) Wait until the resin is tacky and then I put the fabric on the part. (4) Put the assembly in a vacuum bag, seal, etc. (5) Apply vacuum and let it run overnight to ensure the epoxy cures.

I’m eager to learn this process so I can work on some actual parts for my car. I’m still too cautious to work on actual car parts b/c I don’t want to ruin anything yet.

Thanks so much for your input.

[system]

1. I’m still working on getting my resin to composite ratios closer to optimail levels. I think I’m mixing too much resin and the vacuum bagging process is not removing enough of it. However, I think this is just the beginning of my problems. Do you guys weigh out the resin or do you just use experience to guide you?

It’s best to weigh for structural pieces. For decorative/trim pieces I just eyeball it.

2. I’ve been using Release Film (Release Bag-125, .001" X 60" Release Film) from FiberGlass Supply as the media between the resin and the breather fabric. However, I pulled the film off this morning and the resin surface is not smooth at all. It’s full of creases. What type of release media should I be using to get a smooth surface on the part I’m trying to laminate?

Are you bagging the pieces in a mold? From the way you describe it later on, it doesn’t sound like you are. If so, then the texture that the laminate picks up from the release film should be on the inside of the piece. It doesn’t list if it’s woven, though I’d assume that it is. I see they also have a non-woven 125 that’s got perforated holes ever 1/4".

Can I sand resin?

Yes, but be very careful about getting down to the weave of the fabric.

4. Are the steps I’ve been taking correct? This is what I’ve been doing? (1) Mix my resin (US Composites Epoxy Resin + Medium Hardener). (2) I wet my part and wet the fabric. (3) Wait until the resin is tacky and then I put the fabric on the part. (4) Put the assembly in a vacuum bag, seal, etc. (5) Apply vacuum and let it run overnight to ensure the epoxy cures.

What do you mean by tack? You should apply vacuum as soon as possible to the piece. The lower the viscocity of your resin (the more easily it flows), the better the results you’re going to get when pulling a vacuum. The higher the viscocity (the thicker and less easy to flow) the harder it’s going to be to suck up the excess resin and air bubbles in that resin.

[system]

It’s best to weigh for structural pieces. For decorative/trim pieces I just eyeball it.

I’m currently working on decorative/trim pieces…mainly car stuff for now. I guess I’m doing OK when it comes to estimating the amount of resin to use.

Are you bagging the pieces in a mold? From the way you describe it later on, it doesn’t sound like you are. If so, then the texture that the laminate picks up from the release film should be on the inside of the piece. It doesn’t list if it’s woven, though I’d assume that it is. I see they also have a non-woven 125 that’s got perforated holes ever 1/4".

No, I’m not using a mold. I’m still practicing with flat surfaces. I’m actually using small pieces of plexiglass to practice lamination with CF. I was under the impression release films didn’t leave a surface but I noticed the film had very small creases on it so the texture did transfer to the resin surface.

Yes, but be very careful about getting down to the weave of the fabric.

Gotcha…I’m going to try to wet sand the piece I have just to practice. I’ll becarful not to cut it too much.

What do you mean by tack? You should apply vacuum as soon as possible to the piece. The lower the viscocity of your resin (the more easily it flows), the better the results you’re going to get when pulling a vacuum. The higher the viscocity (the thicker and less easy to flow) the harder it’s going to be to suck up the excess resin and air bubbles in that resin.

I meant I waited until the epoxy resin was a little stick so it was easier to line up the fabric to the piece.

I really appreciate your insight; it’s helped me clear up a few questions.

However, I’m still a little unclear on what I’m doing wrong. I wonder if I’m not pulling enough vacuum. Unfortunately, I will not have a vacuum gauge until later this week.

What particular brands of vacuum bagging materials do you recommend?

I’m currently using Stretchlon 200 .0015" X 60" Stretch Film for the vacuum bag. It seems to conform nicely to the part.

I guess my main question is what release film or release material to use?

Thanks!

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Well, bagging a trim pieces that you’re overlaying isn’t the best idea. Bagging is generally reserved for molded pieces or mold making as far as I know. I’d imagine it would be hard to get good results when overlaying though.

Then again, you could try using either the non-woven release fabric, or even glass coated teflon tape that you could wrap around the piece. I’ve seen an example where a guy vacuum bagged a spar for a lightweight model aircraft where he wrapped a carbon rod with a carbon sleeve and then wrapped it in teflon coated glass tape. The finish was pretty slick when he removed the tape, but that would work really well for thin areas.

I’m just throwing spaghetti against the wall, hoping something sticks or helps.

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Here are some things that I’ve noticed.

Your air pocket problem is probably not from the vacuum bag, it’s from your release film. Unless your release film is perforated (another term would be breatheable), any air trapped underneith isn’t going to get sucked through the release fabric. That is why people use breather on top of the perforated release fabric to suck up the excess resin.

Vacuum bagging is used in male and female tools. However, if you’re using it in a male tool situation, your surface is going to be rough because of the texture of the release fabric. What you’ll need to do is build it up with more resin and sand it down smooth like you would in a typical overlay situation.

Evan