Rain Covers FAQ's
W1 Are White Mountain™ backpacks waterproof?
All White Mountain™ backpack materials have a polyurethane (PU) coating and are waterproof to varying degrees. Please visit our page on Material Test Reports for further detail on this subject. The only true waterproof packs are made of vinyl and have welded seams. Waterproof zips are available, but are very expensive and can more than double the price of the finished backpack. There are water resistant zips
now available on the market, but White Mountain™ have not approved the use of these zips in the manufacturing of White Mountain™ backpacks.
W2 Are the seams on White Mountain™ Backpacks Waterproof?
While not entirely waterproof, all interior seams are bound with a polyurethane proofed nylon webbing that reduces water penetration to a bare minimum. If you think it necessary and wish to further waterproof the seams, you can seam seal all seams with a liquid silicon seam sealer, available from most outdoor stores.
W3 Are Internal Liners necessary?
Some backpackers avoid external rain covers completely and use internal liners instead. These less expensive internal liners are heavy gauge plastic bags similar to what you'd see as a garden waste or a survival bag. Others opt for Dry Bags, which are actually designed for canoe or kayaking trips. The dry bags are far more durable than plastic, but also weigh considerably more. The advantage of an internal liner? You still have ready access to the backpack. The disadvantage? The
backpack is not protected on the outside.
W4 Bivvy Bags
We recommend the use of bivvy bags in all circumstances, especially with hiking backpacks. Bivvy Bags will protect your gear from water and allow you to organise your backpack for ease of access. The use of different colored Bivvy Bags is recommended and will enable all your stored equipment to be color coded for ease of identification.
W5 Are Rain Covers Necessary?
Most backpacks have a waterproof polyurethane (PU) coating, that means water won't penetrate the backpack, right? Well actually, NO! Polyurethane (PU) coatings prevent water entering through the fabric, but don't prevent water from getting into the backpack through the seams and through the zippers. Bear in mind that lower quality backpacks have less stitching over a given area, and use a inferior thread. Inferior threads are not tensioned enough to form a tight bond on the adjoining
materials, and this can easily be demonstrated by gaps formed when gently pulling on these adjoining materials. When fully packed a lower quality backpack will expose these gaps and allow greater water penetration. A backpack with higher quality thread that is stitched and tensioned to prevent gaping will prevent excessive water entering the backpack, particularly if bound internally with a waterproof nylon tape stitched over the exposed seam, as in all White Mountain™ backpacks..
W6 What is the correct Rain Cover Size Selection?
Care must be taken in selecting a Rain Cover size. If you strap gear on the outside of your backpack, you'll want to make sure that the Rain Cover will fit over all of the backpack, external attachments and all. A generic XL Rain Cover should be large enough to cover all the gear. A personal choice on size is one reason we do not sew Rain Covers to the backpack, another is that Rain Covers are generally only required in severe weather conditions.