I used a fin panel only as an example where one could eliminate many of the variables and compare the possible differences in results with the only difference being the compression of the composite.
I am not making fin panels.
Recently I stumbled on a ‘new to me’ technique of fixing dings and was going to keep it to myself in ‘secret sauce’ fashion, but heck with that, I’ve learned too much here to not return something possibly helpful to others.
Basically, I got some serious rail dings recently. Granite wins again. I sanded through hot coat to original fiberglass below and a little more. Confined the ding with blue tape. Sand to edge of tape. Standard ding repair stuff.
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I used a 5.5oz Carbon fiber oval covered with a bigger oval of 3.7oz E cloth Oz covered by a bigger oval of 1.43 oz veiling cloth. Yes the carbon is unnecessary, but I’ve enjoyed its ability to bridge ‘soft spots’ under the shell.
I used a ‘wet out table’, saturated all 3 layers together, gravity style, squeeegeed out obvious excess, lifted all three and lightly squeegeed layers into place, to the rail profile.
But then, I used a large thicker Ziplock brand baggie cut open for a single layer and pulled it tight over the rail profile, and worked out the bubbles and extra epoxy with a finger from center to the blue tape edging, and no further. Then, instead of a finger, I tried a stiff well rounded dry squeegee and Pushed on the plastic working extra epoxy from center to edges while pulling tight on the plastic with other hand. I was surprised at how much pressure I could use and how much compression I could achieve and no white spots/dry spots with the plastic preventing air intrusion behind squeegee. I was also surprised at how much epoxy I was able to squeeze out from patches I had already squeegeed on the wet out table of seemingly all excess resin.
As the epoxy slowly thickened it got harder to push the epoxy out to the tape, but the 3 layers of fabric got greatly compressed, and pulled as tightly as possible and had no tendency to pull back/suck back in the extra epoxy. The carbon edges actually squeezed out and look like they were cut by a toddler with safety scissors, but Oh well. This particular board is no looker anyway.
With the plastic, the pressure one could apply pushing, was several fold more times more pressure than one could use had there not been plastic between cloth and squeegee. Using the reflection of the light on the plastic I was able to basically mold the epoxy and layers of fiberglass and CF nearly perfectly to the shape of the rail, without any obvious bulge or edge where one layer of material would end.
After I have pushed the layers as flat as possible with all epoxy pushed to the blue tape and no further, I run a new razor blade lightly inside the tape line, and remove tape and extra plastic outside the tape with it. In a few hours I can pull the plastic and have a perfectly glossed repair which requires little or no sanding, and no more epoxy.
I am wondering if these 3 layers of highly compressed fabric have the same strength as if I had done a traditional fix, where each layer was able to absorb all it wanted and excess squeegeed out then feathered edges then re hotcoated then sanded flush and smooth. I hypothesize that the traditional method would be thicker and therefore have greater strength compared to being compressed and thinner.
But, since there is no more sanding required, and there are the same amount of resin saturated fibers, perhaps it is stronger? It certainly has to be lighter.
Basically there has to be a downside of this simplicity right? This technique of fixing rail dings certainly saves many steps and lessens waste, but it is weaker than the traditional method?
To others trying this squeeging the plastic method, the thickness of the plastic is fairly key to prevent stretching and creases when Squeegeed. I use the thicker white squeegeee, about 3 inches wide with very rounded edges. The Ziplock freezer bags worked far better than regular ziplocks which would stretch and crease too much, I will be researching better plastic for this task, at least for rail dings.
On one larger ding the bag was not big enough. I used two bags. Where the two bags overlapped I could not pull the cloth as tight, squeeze out the excess and the result was less stellar requiring sanding and a fill coat.
I am thinking there are other applications, such as compressing the edges of laps and possibly eliminating the need for a fill coat, or reducing it greatly, By doing a whole side of the board using this method.
With the right plastic, I imagine it could be reused many times too. On one ding I did not razor the plastic inside the tape and was able to reuse the same baggie again.
I know the vaccuum bag guys are achieving something similar, but squeegeeing this thicker plastic over the lamination method allows one to pull the fabric as tightly as possible, squeeze out all extra resin, compress the fabric to an impressive degree, and there is no fill coat required, and no vaccum pump, or peel ply, and it is relatively simple and pretty hard to screw up, with the consequences for screwing up, so far, as far as i know at this point, just being some sanding required afterwards, instead of the pull plastic go surfing methodology if it does come out acceptably well.
I’ve no experience vaccuum bagging, but see many possibilities with this squeeging the plastic method, as long as I am not sacrificing strength by the compression of the layers.
So I come here to ask those with much more experience and knowledge in this matter. What are the repercussions of this untraditional approach?
Any light bulbs going off, or have I been smoking crack and drinking the Kool aid too long?
