IGU Sealant Does Not Dry!

Based on the minuscule information you give, "The exact temp/humidity conditions may not have been met", I'd say that something went wrong.

Are you in the desert? Is your silicone addition or condensation reaction cured?

One part, or two? OK, OK, I know.

Thanks for the prompt reply.

We are actually in Kathmandu and the people involved have a lot of experience in assembly/installation of aluminum doors/windows (although none with IGU's) and are known to have working links with the famed 'Tecnal' of France.

We are not sure of the silicone curing bit. The tech lit referred says 24C & 62% RH.

The exact temp/humidity conditions may not have been met

And those were?

Is the silicon past its use-by date?

Has the correct silicon been used?

Has the silicon been mixed properly?

Where is the plant and what are the weather conditions?

Have you followed the manufacturing procedures properly?

Can you supply more information unless you are only after a guess.

The tech lit referred to says 24C & 62% RH.

Plant in Kathmandu, temp 19-21 max, 7-9 min.

Manuf guide (pulled from glass website) was issued prior to assembly, hence all proper care can be presumed.

Yes, but have you checked the silicon you are using has not passed its use by date.

Get it from the horse's mouth. Thank you.

Philippe! your call!

Yes, sometimes it's the most obvious thing that trips up a production line.

Assuming the silicons good because its just been purchased from a supplier is not enough.

Jack - Also a silicon supplier agent, and yes even we have accidentally sold expired silicon to customers. It happens, so always check the product expiry date before use.

the horse's mouth, m/s philos below!

Looks like you're not alone..................

http://www.shopfloortalk.com/forums/showthread.php?t=30191

Assuming that you are using a one part structural sealant the cure time is in the order of 21 days. Also the older the product the longer the cure time as the additives to enhance curing will have started dissipating. Also storage temperature is important as high temperature has an adverse effect on shelf life and curing times.

Unfortunately not all silicones are equal. It is always better to use an internationally recognised product. I have a storeroom full of useless sealant.

How did the call to the material's manufacturer go (after all, it was "urgent")? Why can't the manufacturer advise?

ref 'philos' below. thank you for your interest.

You don't list what sealants?

By secondary sealant a silicone it is on the outside of the primary sealant making contact with air. The reason I ask is you say you put it around the spacer. If you then cover that up with another sealant. The silicone is sealed in an enclosed atmosphere. If a moisture cure it will never set up. As there is very little moisture inside to draw from.

If it is on the outside with air contact. What was the primary sealant? Was it set up. What was the set up time.You maybe facing some off gassing from the primary sealant that could effect the cure time. Also most IGUs use a Butyl rubber as a primary sealant. A lot of silicone sealant have some type of hydrocarbon solvents. These will attack the Butyl rubber. There may be some compatibility issues.

You also need to make sure that the sealants don't off gas into the interior atmosphere. Some will condense on the glass surface and cloud over time. Also their effects on Low E glass if in use.

http://www.dymax.com/blog/?p=990

"To avoid this effect of humidity, try a 2-part addition cure silicone. They will still cure at room temperature (RTV = Room Temperature Vulcanization) and take away any dependence on moisture."

I have had silicone not dry due to it being out of date or overheated. It still had a reasonable viscosity however. It gets a film over the top and does not dry. Must be removed and replaced with good product.This being standard over the counter tube product, 1 part.

You did not state the type of silicone sealant that you are using. My guess is that you are using a 1 part sealant. For your application, it sounds as if you need a 2 part silicone sealant or a UV cure silicone sealant.

I'm thinking that your application is thick and and the silicone on the inside is sealed off from the components in atmosphere which are required to cure a 1 part sealant. Without exposure to the atmosphere, the sealant behaves just as if it is still in the atmosphere free packaging in which it was distributed. If so, it may take years to cure.

Thanks to all of you for your valuable comments on "IGU sealant does not dry!"

However it turns out that in this case there is no drying problem.

Stressed by deadline pressure and worried over drying substance issue, we overlooked for some time the fact, which we actually very well know and have experience with, that a non-expired leading brand structural sealant, which was used in this case, requires 1 day curing time per 1mm thickness of silicone within the specified range of temperature and humidity, which was complied with here.

Since in the present application an air gap of 19mm was chosen the expected time of cure for the sealant is 19 days, which is far ahead.

Conclusion: don't let pressure get on your wits!