A couple of months ago I too our old Quasar tent out of storage and used it for a night as we needed an extra tent. Nostalgic soon turned to frustration though as the twenty year old material did little to stop the ingress of water during a fairly damp night in the Peak District. The following morning we emerged from the tent distinctly damp, having to step over an inch of water in one corner. It's no surprise really as the tent has seen plenty of action over the years, and never really had any attention other than a good airing from time to time. As it says in the video below, UV radiation from the sun really isn't good for fabrics and speeds up their degradation.

There was no way we were going to throw the thing away so I did a bit of research on re-waterproofing tents. Of course, masters of re-proofing, Nikwax, sell just the product. 

Taking care of the tent in question back in 1999. It's an old tent!

Solarproof comes in a plastic bottle with a pump handle spray action. Applying it was simple. Erect the tent, dampen the material down with a hose pipe, and then spray the white liquid evenly all over the surfaces. It has the look and feel of a weak PVC based solution that you would seal a wall with prior to plastering. The only difficulty i applying is keeping the hand muscles going to operate the pump continually for the ten minutes or so it takes to cover a tent. The Quasar is a small two-man mountain tent and I used the entire 300ml bottle. Once it's on the material I used a damp cloth to spread it evenly. I've read online that some people prefer an aerosol application, but I found no problem with this method. It dried in a matter of minutes.

Have used the tent a few times since and found that it keeps the water out far better than it did previously! Very excited to have our old tent back and also pleased to note that it has imbued some protection from the sun at the same time. Retailing at around £6.50 it's hard to see what's wrong with this, though it could get costly to proof one of the big family tents...

Worth watching the Nikwax video below before buying / applying.

Nikwax Tent & Gear SolarProof