In reply to 2pints:
> The aforementioned jacket is approx 2 years old and as far as I can see in fairly good nick, no holes or scratches and it's never been washed or anything.
As mentioned, your problem is that you've never washed it in 2 years!
How often do you wash your base-layers? Your mid-layers? Why not your outer layer? Did you read the care instructions?
I'll be as concise as I can, cos it gets a bit much but:
Your jacket is "breathable" because there are billions of holes in a layer of PTFE (plumbers tape), which theoretically allow droplets of water vapour pass out. If you've been sweating into it for 2 years, then lots of salts, and grime etc etc will clog up these pores. Also 2 years of water running down the outside will have reduced the effectiveness of the Durable Water Repellancy (DWR) of the outer material. It hasn't gone anywhere, it's just not working as well as it could. Do you notice that the water no longer beads up and runs off? It wets out. As previously mentioned you would find it hard to breathe in a bowl full of water, your jacket is the same.
First thing to do is not to take it back to the shop, but to go to the shop you go it from (or any outdoors shop for that matter), and tell them you need to reproof your jacket, as it's not breathing very well. They will probably recommend either Nikwax or Grangers (Grangers is my personal favourite). You may think that they're bumping up the price by offering you the Nikwax Techwash (which is nothing more than a soap i.e. it's not a detergent), or the Grangers Cleaner (same applies). They're actually trying to help you out. A clean jacket will 'accept' the reproofing agent than a grimey jacket. It's like applying glue. No point putting it on a dirty surface, cos you'll just glue the dirt!
When it comes to the reproofer, the helpful shop assistant should ask you if it's a 2-layer, or a 3-layer garment. If it's 3-layer, then that's fine and dandy, and you can use a wash-in reproofer (Nikwax, or Grangers again), however if you've got a 2-layer garment, then you're gonna have to go for the more expensive (and labour intensive) option of the spray-on reproofer. You have to spray the stuff on, and then rub it into the material with a sponge or cloth or something.
Once you've done this, you're nearly ready, but not quite yet. You've got to either shove it into a tumble-drier on the lowest setting for 30-45 minutes, or put your iron on the cool setting, and iron it slowly, making sure you get plenty of warmth into the garment. Don't melt it though! If you don't do this, the reproofer will wash off in next to no time.
Don't even think about taking the jacket back as "no longer waterproof". The chances are it's simply not true.
If you want to check the waterproofness, then put the jacket on the floor, and pour a cup of water onto the outside of the jacket. Give it a bit of a rub, try and see if you can push the water through the material. Leave it on there for 15 minutes. Then pour off the water, and feel the inside. Probably dry. The outside will probably be wetted-out though. Do the whole clean-reproof-heat treat job, and then try again. The water should run off quite easily.
And yes... I do work in a shop. Hence why I recommend Grangers.
P.S. There are other companies too. I've heard that Storm are very good too, but G still get it in my book!
