With our nice weather we are having, I had an idea to set up a sheet of plywood on saw horses outside and baste a few quilts , since I dont have much room in the house .....

BUT,

if I cant get to quilting them untill this winter -- is it bad to leave saftey pins in that long ?? I have never thread basted .... I also have one of thoes guns with plastic "tags" I havnt used ....

whats your opinion ?!?!

I'm not sure..I spray baste..I have taken those outside..they store just fine!! Safety pins are probably safe in this day and age..they shouldn't rust..if that's what you were thinking !!

I would be leery of leaving saftey pins in that long especially in humid weather. I would go with the tag gun. I've used mine on different occasions and like it. YOu don't just push it thru the 3 layers, you actually do the same motion as pinning. Down thru 3 layers then back up. I would try it on a sample sandwich and see how you like it.
Maybe someone else will have personal experience on leaving the pins in an can give you a definate answer.

Make sure you use stainless steel safety pins so they will not rust or leave marks. I keep my pins in a plastic box so that they stay clean.

You could always try this method - I think it would be better than safety pins and not take too much longer - and you can leave it in for as long as you need to :D
http://www.youtube.com/watch?v=bhwNylePFAA

spray baste or thread baste is probably your best bet

I wouldn't do it.

I don't have a problem but I live in a dry climate. If it's humid where you live there might be a problem.

Safety pins will more than likely rust. Especially if you live in a humid climate.

If you are truly going to get to them this winter, I wouldn't be concerned with rusting. Of course, I'm assuming that once pinned, you'll be storing them in a climate controlled home. If something happens and you don't get to them, I'd probably remove the pins. I've found things that have been pinned for years, some rusted, some not.