Overlay Dilemmas

General Composites Discussions Composites Talk
#1

Okay,

This last weekend I did some overlay work with silver tex and some clear poly surfboard resin.

Here is what I found out about overlays…THEY SUCK!

Really, had the subwoofer boxes been less compound curved and I had some way to lock the fabric agains the box without problems Id like doing them.

So now I want to know…WHAT GLUE CAN I USE TO HOLD THE CLOTH DOWN EVEN WHEN I START USING THE RESIN?

For me, I tried one using a light coat of resin that got tacky…I waited another hour and tried to use more resin. That just let up the cloth (solvents loosened it up?) and I was fighting air bubbles.

Then After a failure I redid the second box and used 3M super 77 which using the finger tack test, was much stickier than the infuzene I have…but as I suspected the resin let the cloth loose from the glue.

THERE HAS TO BE A GLUE THAT HOLDS…anyone want to help me out here?

#2

I’d think the Infuzene would work the best but it is for holding dry cloth together for VIP.

Surfboard (sanding) PER resin has surfacing agent which is wax that comes to the surface. Try a lamination resin (no wax) until it before the “B” stage, then apply the cloth (you might want to paint the box black first as the grey primer will show thru) and then after all in place, then use the surfboard PER to top coat it?

#3

I had the same problem with 3M super 77 when overlaying my counter tops. As soon as I put the epoxy on it, areas would bubble up. I pushed it down with my brush, but that didn’t help.

#4

Infuzen does nothing over the 3m…as far as I can tell its only benefit is of being able to cross link with the resin.

I know someone makes some glue that will hold up to this stuff…

#5

Maybe show us what it is your trying to overlay and it’s size too?

You could lamination resin it down, envelope vacuum bag it and then later top coat it. You might even be able to use a wood workers wood bending system which is really cheap.

#6

couls you just put a layer of resin let it get almost tacky then put the fabric down, let it cure onto the fabric then lay resin over it?

#7

here is the problem with the resin situation…Im guessing this is only with the clear surfboard poly though

If I lay some down, let it start to tack and then lay the cloth, you have to catch it at the exact right time and then make sure it stays down until its fully cured.

As far as Ive seen, if you let it just cure up a bit more and then start your build layers, it just releases the cloth from the resin.

Im going to call some people and see what I cant come up with. I dont want to watch resin dry and I dont have time to do a set of sub boxes three times again.

I lost money on this job…

#8

So, here is my take on this. You really have two choices for overlay. You can continue with the PER but will almost inevitably have to resort to vacuum bagging to hold it. I prefer epoxy for overlay because the bond to the sanded plastic is better. Like the Dual man said, let it get pretty tacky then lay the cloth over it and cure. The drawn back to this process is that you pretty much have to put the cloth down right the first time because it gets real messy to pull it up. I like to spray down a few layers of Top Coat to get a flat surface next. Here is an overlay that I recently completed -

On this same topic, I was looking as some OE pieces recently and they were not really even composite overlays. It looks like the glued the material down and sprayed many layers of auto clear coat over it. So, I guess there is a third option out there. Anyone try this?

#9

we thought about doing that, it would have been the easiest way to keep it locked in but I was skeptical about the clear not disolving the bond of the glue as well!

#10

Nice out come what top coat brand did you use? As for the silver cf that this is really hard to work with. I have done couple of overlay with it. I use the 3m 90 spray, spray the part and the fabric let it become tacky for 30sec then just put them together. I also use the Silmar 249 poly resin. The first coat I use a foam brush and apply a really thin layer and just let it tack up really good or almost dried. Then I apply more layers of resin. Hope this helps.

#11

Kyankton, I am new on this and I’m still practicing before attampting my first CF work, but I wonder how did you manage to do an overlay over such a surface. As far as I understand the CF does not strech, so how did you do the overlay over the rounded parts without getting any marks? Thanks in advance