Why can't I use fabric conditioner on jeans?

[Madmog]

Bought some new jeans recently and I've noticed the labels say not to use fabric conditioner. Does anyone know why? I've been washing my old jeans along with everything else in fabric conditioner and they always seem okay.

Are they expensive? I know VB's label, Moschino etc jeans tend to say not to use fabric conditioner. I did anyway and it ruined the colour of both pairs. Luckily, the companies were lovely and replaced them, after giving me a long chemistry lesson on the phone! It infiltrates the material and pulls apart the colour, apparently, ruining both the colour and the fit. I haven't done it again since!

Although I did ruin OH's favourite t-shirt yesterday, and I feel terrible for it

I've stopped using fabric conditioner at all, and come to think of it some jeans I've had a few weeks haven't faded yet (fingers crossed) I've been washing them a lot less than I normally would though

Thanks for your replies. They are made by Next. Already washed two pairs when I actually read the label and can't see any difference. I was wondering if it would make a difference to colour/fit longterm and that's the reason why. I have another two pairs I bought also from Next so might try washing these without fab con and see if there's a different in a couple of months.

Fabric conditioner rots Lycra too. If they have Lycra in, this may be the reason.

They have elastane which I suppose is stretchy like lycra.

Lycra is a trade name for Elastane I think. They are the same thing anyway.

Thanks for that. As a matter of interest I think I'll going and recover my old jeans (ready for throwing out) and see what they were made of!