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I have been installing Sportster tail ribs with Hysol 9460. The epoxy seems to be setting up well and hard as epoxy should be. I question the little white specs that appear to be resin that did not disolve in the mixing. Is it normal to have white surface specs after curing. Thanks. Dave in Cincinnati.
How old is the Hysol you are using? How long has it been since the Hysol was first opened?
Dave S
St Paul, MN
Dave,
Sorry, I should have mentioned. I received the Hysol in November with my wing kit. It is good until October 2011. It looks like it is very fresh. The hardener is like black grease and the resin is like white play dough. I mix it until it is uniform gray in color. It dries and hardens looking just like I think it should. I just wonder why the little white specs, flakes whatever they are? Thank you for your reply, Dave.
Dave G,
The hysol is well within its expiration - that shouldn't be a problem.
I had a can of the white part which I had partially used, then set on the shelf for a while - in that case - I found some somewhat hardened stuff up around the inner lip of the can that behaved the way you described - made a few little white flecks that stood out - not many, but real easy to see. Kind of avoided the issue by being careful when I took the the goop out of the can so as to avoid the rim and the particles. I am not a hysol chemist by any means, but I speculate that some oxidation of the white stuff can take place in a partially used can if a thin film of the stuff is smeared around up the insides of the can and on the rim since there will be ample air/oxygen available in quantity once the can is partially empty.
I had to do some experimenting with the hysol after I was done using it - curiosity, you know - let it age well past its expiration date - the white stuff got thicker/started to harden up a bit and developed an obvious crust on the exposed areas; and, the give-away on the black stuff is that it started to smell like ammonia.
If you are within the EXP date and it has been stored in a normal storage temp I have a hard time thinking the main mass of the material is anything other than OK.
For what it is worth I had some Hysol where the white stuff developed a bit of a crust, warmed it a bit (in a jar in hot water) an it went right back to a nice smooth consistency. All appearances are that it cures hard and bonds well. I am also not a Hysol chemist, just my observations.
Thanks for your ideas guys. It sounds like the specs are no big deal. I know I have the right mix. I am using a powder scale to get the same weight before mixing. The online instructions for 9460 specify it can be measured by weight or volume. As I said it feels and looks like it is very strong. I can tell if I tried to remove a rib from the tail it would splinter, but leave the epoxy right where it is. I still have a few more ribs to finish in the tail before I move on to my wings. I just want to make sure my epoxy method is safe before I start "gluing" structural members like wing ribs and spars. Thank you for your help. Dave in Cincinnati.
We preheat the white Hysol in the microwave for 3-5 seconds before mixing. This rejuvenates the dried specs back into the creamy texture. Don't heat after mixing, though.
Mark,
Thank you for your idea. I already received a suggestion to warm in a jar of warm water. I'll try both to see what works best for me. My wife may not be too keen on me taking the microwave out to the garage.
we used to have to repair holes in cargo bin floors on big jets with a two part epoxy . in the winter you could hardly get either part a or part b to squeeze out of the tube when they were cold . the easy way was to put both tubes on the windshields defroster vents of the pickup truck for 15-20 minutes to warm them up . you learned fast to take the tubes up in the cargo bin and mix it there after it was warm . both parts would then almost run out of the tubes . the down side is that the heat greatly reduces the working time once they are mixed . sometimes it would harden before you could get the repair made or even get it mixed all the way .
Mark, I tried the microwave trick with my Hysol resin. It worked beautifully. I am not sure why but it sure worked. I now have very pretty creamy gray epoxy fillets on my latest ribs. Thanks again, Dave