Can I use Sikaflex past its "use by" date?

OK Campers,

I have a (approx.) $300 question. An unavoidable delay in my project has left me with 3 tubes of Sikaflex-295 UV and a can of Sika Primer 209D which are past their "use by" dates. The 295 Adhesive says "best before 02/2010 and the 209 Primer says "best before end of 01/10.

A chemistry professor friend and 9A builder told me to just use them. Is there anyone else out there who used these products after the use by dates and did not lose their canopies and go down in a flaming ball of death?

I can use some advice.

Thanks

i will

I have some 2 year old stuff I intend to use on the canopy skirt. I glued a test piece and it holds great. I think as long as the stuff comes out of the tube you are fine.

I am no chemist so i really don't know why ther is an experation date.

Cheer

I've got some Proseal about 6 months out of date that I'm using to fay-seal some areas but I bought a new quart to do the tanks of my RV-10. My thinking is that the old stuff might be fine but I know the new will be good and the cost is worth my peace of mind. Sika is amazing stuff but losing your canopy would ruin your whole day, if not more. I'd bite the bullet and get a new batch. It's not that expensive.

Another 2 cents from the peanut gallery.

So Steve I happen to know that you have visions of flying your RV-8 around the world.

So there you are half way across the pacific. Poof there goes the canopy. But wait, its no bg deal, your still flying and your not dead.

"Oh ****, my speed just dropped 10 knots, drag is bad, fuel planning down the tubes. Im never gonna make the beach head. Dang it. Shoulda bought that new tube of glue."

If it were me, Id use the old tube. But I typically fall into the risky idiot category.

glue

buy a small amount and use it on front and old on back

The ?Expiration date? for me is most often times based on me testing it and see its condition. We usually keep our milk way past the date that is printed on and seldom goes to waste.

Of course this has much to do with the condition that it was kept? proseal or other glue kept in a cool environment will last much much longer then on the shelf in the garage.

My Experience and Opinion on Adhesive Expiration Dates

Was the product stored in a cool dry place, does it have a manageable viscosity, and there is no separation of the solid or resin portion? If the answers are all yes, then it is good to use. When adhesives start to cure in the container, the viscosity increases until it becomes unmanageable and it looses many of its adhesive properties. Sikaflex cures as it reacts with moisture in the air. So, as long as it was stored properly, sealed against moisture, and has a manageable viscosity, then it is usable regardless of the expiration date stamped on the package. The rate of all chemical reactions are a function of time, activation energy, and temperature. Cooler temperatures equal longer work life. This is true for sikaflex and Proseal. I store sikaflex and unmixed Proseal in a freezer and use them whenever required. There is no scientific reason why an adhesive can be used for up to 12 months and then automatically becomes unusable after 12 months and one day. Expiration dates are arbitrary and typically arrived at without any test data. The main reason for the one year expiration date is that vendors decided that it is in their best interest to coerce their customers to throw away perfectly good adhesives and buy more stuff from them.

As an example, I worked in the electronics industry for 25 years as a Process Engineer and we stored many two component pre-mixed epoxies in the freezer prior to thawing out and applying. There was a one year expiration date on all our epoxies (sound familiar). I did a literature search and found a paper written by a NASA scientist who extrapolated out work life using the chemical activation energy and predicted that this type of epoxy when properly stored in the freezer would have a usable storage life of more than 1000 years. I sent a copy of this paper to the epoxy vendor and asked them to rethink and extend the one year expiration date. They weren't in the least bit interested in changing the expiration date. So in order to comply with ISO-9000 regulations, we changed our process instructions to state, "Frozen epoxies are usable for up to five years after the expiration date", and used the NASA paper as the reason for this decision. We completed extensive environmental testing of all products using these adhesives and we never had a problem with properly stored epoxies even when using them years past their expiration dates, and we saved a lot of money.

Sika

Whatever Larry D. Says PLUS I used screws every other hole so mine aint goin nowhere

I would not use it.

Steve, why take a chance with the most difficult and time consuming assembly on a RV-8? What if it comes apart? Consider the work.Your a lawyer, would you advise a client to take such a risk? When the expiration date on the milk in my refrigerator is past I can smell and taste test to decide to consume or feed it to the dog. You got no way to test this stuff for strength 6 months after you use it. The UV effects and adhesion level, etc. I used two tubes to mount my canopy and windscreen at about $19. bucks each and the cleaner and undercoating was about $100. Course prices go up, but with all you've already spent and that you and your family will be flying in your plane is there really a question? Call Jamestown and order some more. If you provide lunch I'll come help you mount the canopy. I've done two. Best regards and it's good to learn your building again. I finished my RV in June, Bill Phillips, RV-8a 17 hrs Phase l

Anyone want some old Sikka?

Thanks for the thoughts guys. I value your judgment.
At this point, I guess discretion is the better part of thrift.
Good thing I did not get into airplane building to save money.
I guess now I will order new tubes and can the old stuff (or, as Bill suggested, feed it to the dog!).
It's just good to be back in the shop. It's all good!

Other Uses

I used my old Sika to glue some alum map pockets on the interior, leading edge of the skirt. It's holding fine, but it certainly didn't cure as well as the new Sika.

So...I agree with your decision...however - you might find some non-critical projects for that old Sika!

If you're gonna toss it,

I'll give you $10 for it. And shipping!

Sika Process

-8A. There were 2 basic steps in the Sika canopy process - 1) Structual application to actually attach the canopy; 2) Cosmetic application to make it look nice.

I'd buy new stuff for (1) but use the expired stuff for (2).

A question I asked before on this forum but should be periodically addressed: Has anyone had any problems with the structural integrity of their Sika canopy install as the timeline progresses? I'm 2 years since install and 90 flight hours since first flight in Apr 2011 with no problems.

$$$$$$$$$$$$$$$

Sealant expirition dates are a racket,,,,,,,, Went thru this when at the airlines and nobody could tell us what the dates were based on!

Keep them cool and dry and they last way longer than their posted dates. If they mix and cure properly they are good to go. Glad shops get rid of them when they are expired... saved me a lot of money!