So I've just put a new head on this old fin (tuttle -> power box). The whole project has gone well but I didn't think about getting the air bubbles out of my glue mix when I glued the fin into the new head (conversion kit).





Now that I think about it I'm concerned that the air bubbles are a weak point. The mix is International epoxy resin with some microfibres to thicken it out - but still a pretty runny brew as I bolted the fin together first and then poured in the resin.

I had plenty left over which I left to set in ziplock bag. I've cut out a section and wet sanded it in the hope of getting an idea of the integrity of the final cured glue. Here it is:



I was hoping some one could give an opinion? The conversion kit included two through bolts (which I fitted) so maybe I'm worrying about nothing?

Some more pics showing bubbles that rose to the surface:

Should be fine. To toughen the resin no matter what type /quality epoxy it is, it will benefit from a post cure. Let it cure at room temp for at least 24 hours then give it 30deg for a couple of hours, then ramp it to 40 deg for an hour, then 50 deg for 5 hours or so. This will toughen the resin far beyond what a normal room tempeature cure can acheive. To go to extreme, some resins will cure to a brittle state at room temp only (called b-staging) and not acquire any strength/toughness at all until they have been post cured. As with any epoxy you MUST ensure accurate mix ratio, not yeah that looks about 4 to 1 or whatever the ratio may be.

My mix was definitely 4:1, but I had no way of putting together a vacuum chamber. I like the pouring idea I'll try that next time.

Is it better to get the bubbles out before or after adding in the microfibres?

Hey ikw777 you mention a "conversion kit"
Is there actually one available, if so where???????????

You're probably putting the bubbles in yourself when you mix your resin.

use a flat stick or spatula to mix your resin and stir slowly don't whisk it up

Should help

So that old Finworks fin I used will be OK then? I think its a glass fin??