preserving jars

You wouldn't be able to sterilise the jars in the oven, cos the plastic would melt....you could try something like milton to sterilise 

Try that then.
As soon as the jars have completely cooled you will know that they have sealed/formed a vacuum properly by trying gently to lift a lid it should be stuck fast......if it doesn't work store in the fridge or reboil and use other jars. Good luck

If you have a few of them and can risk writing one off it might be worth a trial of sending one (with the plastic still in situ) for a dance in the oven at a suitable jar sterilisation temperature such as up to 150 degrees C.  You may be pleasantly surprised and find you get away with it.  Found that I got away with it first time I inadvertently left the plastic ring seals in place when sterilising a batch of ikea kilner-like clip jars and have simply left 'em in place ever since when doing the jar sterilising bit.

Incidentally I reckon Sodium metabisulphite is cheaper than Milton if you prefer to stick to chemwar!

That's a shame.
Still, was probably worth the try - the potential 'gain' would have been useful as a way of getting the jars into sterilised use without the disassembly and chemical faffing.

edit: (just realised) - 85-90 means they actually melt in boiling water so it has to be chemwar as boiling water sterilisation is also off the palette!

Of course, sooner or later someone on here will mention to you the sevenpenny glass jars that come continaining material that is almost, but not quite, entirely unlike curry sauce!  Amazing supermarket loss leaders and perfect for jams, pickles etc once you have thoroughly cleaned/deodorised and sterilised them!

Oh.   Looks like it is me this time.

I tried the curry sauce jars - Just couldn't bring myself to tip the contents away, but could eat it either 

I like coffee jars ... Heres my "spice" cupboard.