Does Fiberglass bond to Sikaflex?

[mlwynn]

This is a question I asked myself this weekend. I sikaflexed in my windscreen and was looking at the fiberglass fairing and trying to figure out if I needed to go over and around the sika or could go right up onto it.

When I first started the sikaflex for the canopy, I had a spare piece of powder coated material to which I did a standard sikaflex attachment both of plexi and fiberglass. It is well documented that Sika bonds really well with both. The question in my mind was, can you put wet fiberglass onto a sika surface and expect it to bond properly.

I mixed up standard epoxy resin and squeeged it into 8 oz cloth. I applied this a couple of ways to cured sikaflex that was bonded to my original test surface. Let it set up over night and then tried to pry it off. No dice. The sika rips before it lets go of the fiberglass.

Thus the question is answered. Fiberglass can be applied to Sikaflex and it will bond very tightly. Thought I would share this experiment with the group.

Regards,

Michael Wynn
RV 8 Finishing
San Ramon, CA

[Paul K]

My experience, and I made lots of samples of different bonds and then pulled them apart or tried to pull them apart, is that Sikaflex will bond to just about anything including cured fiberglass. However, applying fiberglass over cured Sikaflex creates a marginal bond at best. Try it, make a sample and try to pull it apart

PS, don't forget the Sika primer.

[db8]

I'll second Paul's thoughts. Dave

[lockeed]

Being in the RV Trailer and motorhome business, I can assure you that Sikaflex will bond to fiberglass very well indeed.

Cheers.

[BillC]

Michael,

I used Sika for canopy bonding and then some extra to sort of blend in the transition from the canopy to the deck. After that I used fiberglass layups to further smooth out the transition. That was in 2007. As of today I have seen no signs of cracking or delamination.
So, I would say that at least for this short time frame (~4.5 yrs) there are no issues with the bonding of fiberglass to Sika-flex.

YMMV
Bill

[mlwynn]

Thanks for your comments. I was quite sure that Sika would bond just fine to cured fiberglass. It was the opposite I was looking at. I made a series of experimental bonds and it seems like fresh fiberglass and resin bonds very tightly to cured Sika--at least based on my simple experiment. The Sika tore before it let go of the fiberglass.

In this usage, at the windscreen junction, there is nothing structural I need to worry about. The windscreen is secured by the sikaflex. The fiberglass will bond pretty well to the aluminum and plexy. I guess I was most worried about the fiberglass peeling off the sika and water getting trapped underneath and tracking down to the aluminum of the front skin. From what I can see, I don't think that is going to be an issue. Once the fiberglass is all finished, I will probably run a tiny bead of Sika over the edge again and call it a seal.

Regards,

Michael Wynn
RV 8 Finishing
San Ramon, CA

[JSBergen]

Michael,
Just a quick clarification, did you put any primer on the cured sikaflex prior to placing the fiberglass on it or did you apply the fiberglass directly to the cured sikaflex?
Thanks,
Jamie

[mlwynn]

Hi Jamie,

It was just a quick little experiment, so I didn't do any prep at all. Just mixed up the resin, squeegied it into the cloth and put it on the cured sika. Seemed to bond quite well without any particular prep.

Regards,

Michael Wynn
RV 8 Finishing
San Ramon, CA