Since I ride year round in all manner of weather I need apparel that is both water repellent and breathable. I've converted several articles of cotton clothing to waxed cotton (ie tin cloth, oil skin) using a recipe of linseed oil and paraffin wax (sometimes beeswax when I have it), however these articles of clothing can be cumbersome to pack when traveling and be very stiff in colder climates. I do have Gore-Tex jacket and pant skins when I desire water repellency AND breathability but even GT can wear out after a few years and lose it's desirable characteristics... and let's face it, the stuff is seriously expensive. So I decided to try a product that supposedly will rejuvenate GT materials and even make man-made as well as natural fabrics water repellent. The product is called Nikwax.
So far I've treated my tour-tried and true Cabela's nylon rain/barn coat, a pair of $1.75 cheap cotton double-lined gloves, a pair of cotton plimsoles and an old cotton t-shirt to wear in the summer during my commute to work in rainy weather (an alternative to baring my 49 year old pasty out of shape torso vs arriving at work with a drenched t-shirt). I have to admit that I'm very impressed so far. I never thought that anything could work as well as good old fashioned waxed cotton as far as water repellency goes but so far this Nikwax has proven to bead up water like a duck's back yet leave the clothing as dry as when it last came out of my dryer (yes, my dryer does function properly). I have yet to experience it's longevity as compared to waxed cotton but the fact that it repels water so well yet leaves the article of clothing as pliable as intended really impressed me.
You may want to check this stuff out... IMHO it beats the functionality (and hot box characteristics) of PVC rain gear and the high price of Gore-Tex.