Waterproofing old backpack rain cover

Hi

My backpack rain cover (cheap, integrated cover) has had a battering and lost its waterproofing. I would like to waterproof it as cheaply and effectively as possible. I have nikwax and use it for my clothing but this seems rather overkill for something that will not sweat. Is there a dirt cheap waterproofing option I could use instead please?

Thanks
Dan

You could paint it with a silicon and white spirit mix; that should work. Personally I'd cut it off and use an internal liner....but then I think pack covers are the devils spawn.

Thanks Ed - that sounds like a good plan

It's actually for my bike commute so protects the bag from more than just rain. Out of curiosity, what's up with pack covers?

Now...the only silicone product I've ever bought is the stuff you line the bath with. I'm thinking that isn't what you had in mind. Is it?

Thanks
Dan 

I've only used the 'expensive' seam sealer type Dan - but I believe the sealant stuff works; plenty of web advice on what to get and ratio of mixing with white spirit if you search?

Pack covers....well, they bedeck the mountains where blown off packs, flap, are baggy, highly coloured, probably reponsible for global warming and a threat to world piece....need I go on...and on...

...bath seam sealant (the non acrylic ones) are 100% silicon. From what i can tell the smaller, more expensive tent seam sealants are exactly the same thing.

Clear bath silicon & naptha (Coleman fuel or panel wipe) or diluted Banana Oil.

Scissors would be preferable.

White spirit mixed with 100% silicone (yes, the stuff from B&Q) mixed to the consistency of olive oil. You can either lightly paint it on or wipe it on with a sponge.

Include a little history in your walks. Pecsaetan - Ancient Derbyshire, Staffordshire and South Yorkshire - http://pecsaetan.weebly.com/

maybe buy some proofed n ylon  & sew it over the old cover? That way you keep the  elasticated/attachement bit.
Not neat or tidy or weight concious, but fine for bike commuting, i'd say

For theprice of any sealant you can buy another. I found some on ebay for £2.99

Throw it away and get some pannier bags