I use to live in WA state, had plastic tubs with lids sitting on my back porch for 10 years, Even rain mist would touch them, nothing ever got damp or moldy.. maybe I was very lucky, Not all material, some clothing and odds and ends.

I've had fabrics stored in plastic totes since in the 1960's when I started building my stash for when I retired 30 years later. I still have a lot of this fabric and it's just fine. No odor! No fading! No dust!

I have had an experience with brown discoloration on a couple of cotton fabrics. They were stored in my attic in plastic bags (trash type bags) one was a piece of fabric and some was leftover from cutting out a dress for my daughter. They weren't in the same bag, or box but these 2 items had some areas of brown discoloration. I was going through all my fabric especially "scraps" as I wanted to use the scraps from her dress in her quilt I'm making (there will be enouch of her dress fabric to get a patch :-)). Most of the fabrics were fine except for these 2. So it probably was the bag, being in a box could have an effect as well. So it could be just random occurance, and maybe I won't use trash bags to store fabric or out of season clothes anymore.

What's the alternative? How do you store your fabric?

here is a link from e how telling just how to store cotton fabric

http://www.ehow.com/how_6021666_stor...on-fabric.html

I store my fabric in a closet on wooden shelves, with acid-free tissue paper between the shelves and the fabric if I care a lot about the fabric. If it's Joann's stuff that I care less about, it's just on the wooden shelves. I try not to use plastic at all unless I have to. I also try not to have so much stuff that some of it needs to be stored elsewhere. I have a healthy fabric stash, but in general, if it's in storage, I'm not enjoying it, and I have to ask myself, do I really need so much stuff, anyway? If my home starts to overflow, a trip to the local charity drop-off station is in order.

I store all my fabrics in plastic bins with tight lids. I've done this for many, many years and have never had a moment's problems with my fabric. I replaced all my plastic bins after christmas because they stacked better in my sewing room and did not find even one spot. I never have however stored fabrics in plastic grocery bags so I would not know what results you might get. Silica crystals placed in plastic bins will help with any moisture problems.

the problems you might incounter would be moisture build up or condensation.

I have had fabric come out with spots on them but these are usually fabrics that I have handle a couple of times and put away,meaning my hands were not as clean as they should have been. I have worked with a of wedding dresses and that's were I have seen this happen the most.

I have used plastic for years with no problem.