Wetting out revisited- roller options.

General Composites Discussions Composites Talk
#1

Some time ago, I asked about potential problems in sufficiently wetting out carbon fiber with epoxy. Generally speaking, the responses were that it was not so difficult. However, I remain concerned, because thorough wetting out seems to be the most important aspect of CF fabrication if one wants a finished product with maximum material strength properties.

If we consider wetting out large flat pieces of thin to medium weight fabric (say 100 to 200 gsm) there appears to be five specialized rollers for the job. They come in many widths. I am most interested in the 3" as a good compromise for most applications. I am not sure if these tools have specific names, so I will have to describe them.

  1. Smooth flat rubber roller.

  2. Aluminium roller with grooves or rather fins, closely spaced, and oriented like many small and thin wheels stacked together.

  3. Aluminium roller with long straight fins running parallel to the axis.

  4. Roller with short nylon bristles.

  5. Roller with finials, like #3 only with many grooves cut radially. The pattern it would make in soft putty would be many very short and closely spaced lines.

I would be curious to hear any observations or opinions from those who have used such rollers. Any favorites? I bought rollers in styles 1,2,3, and 4, and have tried only #1 so far. Yes, I know experimentation is the only way to know for sure, but I am still curious about how others view these specialized rollers. I am also wondering if the styles favor certain types of fabric, e.g., unidirectional vs plain weave.

#2

  1. A rubber putty knife, wallpaper knife, or “squeezee”. Slide it over the fabric with some force, and you work the resin in, and air out.

  2. The one with nylon bristles is perfect for CSM/polyester.

  3. Paddle rollers. Some like them, mostly in polyester business, but they create a spray pattern behind the roller, and over your arm…

#3

How many people actually use rollers when laying up epoxy and carbon fibre?

Based on my limited experience it seemed that a brush was all that I needed (easy “pressing down” type motion with the large flat side of the brush), didn’t have to work the layup anywhere near as much as CSM. Then again I was doing it for visual carbon, I didn’t want to use a roller for risk of disturbing the weave.

So why would rollers or a squeegee be used? Just to work faster? Or does it actually provide a benefit in some other way?

#4

I prefer to use plastic squeegees as well. They allow you to press the resin into the fabric much more easily and are much easier to clean since you can just wipe them down with some acetone when you’re done - or just toss them since they’re so cheap to begin with.

#5

@mugget: A brush can indeed be enough, but on larger projects you want something larger. A 20cm/8" squeegee can be great on for instance boats, but are useless when doing a dashboard, as an example.