What could have caused this?

[RrogerD]

These are the large, 500 x 1.5m panes in our conservatory. All of them are the same. They were like this when we moved in 10yrs ago, although they have gotten slightly worse over the years.
They obviously shouldn't be like this. I'm just wondering what would have caused it? Is it over-heating? Or poor product? I've no idea of the manufacturer unfortunately and I dare say after ten years, no recourse to be had anyway.

 

[crank39]

I've seen similar but not this, I've seen that type of spacer bar too and it's old your right, that gunge might be the hotmelt or polysulphide seal but why and how it's reacted like that, maybe it didn't like the duct tape they sometimes apply around the perimeter on the glass, maybe @ronniecabers would know

 

[ronniecabers]

Not 100% sure but looks like old ' swiggle' strip spacer bar, can't remember ever seeing it in white/grey before. Does look like something ' acidic' has been applied somewhere to the outer edge and its melted. I have seen many a sealed unit fitted in wood with normal silicone ( should only use LM / Low Modulus silicone) which has melted the polysulphide sealant, never seen one ' melted ' inside like that before though and certainly not in upvc

 

[RrogerD]

Not 100% sure but looks like old ' swiggle' strip spacer bar, can't remember ever seeing it in white/grey before. Does look like something ' acidic' has been applied somewhere to the outer edge and its melted. I have seen many a sealed unit fitted in wood with normal silicone ( should only use LM / Low Modulus silicone) which has melted the polysulphide sealant, never seen one ' melted ' inside like that before though and certainly not in upvc

These are mounted in wood. Although the 'gunge' that's melted is inside of the sealed unit.

 

[ronniecabers]

Ah, well it could well be the silicone that has been used around the perimeter of the sealed unit then ( sealing it in the woodem frame ), the reaction between the non low modulus and the ' hotmelt' sealant could well have caused that ( assuming non low modulus silicone used ). Had one in our office many years ago that a builder had sealed in with non low modulus silicone and it left a horrible gooey black mess where every it was put down as the hotmelt melted/reacted. Only solution is replacement units

 

[crank39]

Your right ronnie, its probably reacted with the acetic acid in the high mod acetoxy cure silicone, it was used extensively back then, even remember using it myself when i first started up late 80's start of 90s, horrible vinegary smell when curing

 

[RrogerD]

Your right ronnie, its probably reacted with the acetic acid in the high mod acetoxy cure silicone, it was used extensively back then, even remember using it myself when i first started up late 80's start of 90s, horrible vinegary smell when curing

That doesn't surprise me as the property is 80s and the conservatory therefore likely 90s. However, if the windows are sealed units then how would they be effected by anything outside of this?

 

[diy_fun_uk]

That doesn't surprise me as the property is 80s and the conservatory therefore likely 90s. However, if the windows are sealed units then how would they be effected by anything outside of this?

I think although the units are 'sealed', around the sealed edge there could be scope for chemicals to leach into the inner cavity, in this case from the silicon. It's not the same thing, but it's a bit like referring to a sealed unit that's failed and has condensation inside. It's failed around the sealed edge, allowing air in and moisture to form.

 

[crank39]

Although commonly referred to as 'sealed units' the seal is actually permeable, in the case of an A rated window having argon filled units(to achieve the rating) no one will actually tell you that the argon will have all but seeped out within 4/5 years apart from the honest trade guys like myself on here or a manufacturer of units like ronnie