Best Way To Deliver A Multiple Of Sheets?

I have 15 sheets (x30 stamps) to post overseas and would value members opinion on the best way to protect them from moisture en-route. It would be distressing to find some dampness along the journey had stuck them all together.
TIA

I have used plain plastic bags or zip lock type bags. If a plain bag I sealed the opening with packing tape. The short trip in the mail will not cause plastic chemicals damage. A cardboard or other stiffener should be used to prevent the sheets from being folded or creased is also necessary.

quigngt - many thanks for the suggestion

Yes, some sort of plastic weather-proofing and a stiffener would be a great idea. Sometimes however, the corrugated cardboard type stiffeners can be an actual detriment to anything inside your package because they tend to crease easily and keep bending in the same spot and doing even more damage so, maybe use something with just a little bit of "give" but not too stiff for the postal machinery to handle. Just a thought I'd pass along to you.

There's a type of cardboard called chipboard that better for mailing items. I buy it in large bundles from a mailing supply warehouse, but I understand it is also sold at scrapbooking supplies and craft stores. It is rigid, but thin enough to do the job. Most likely you'll have to mail the sheets at the package rate due to size dimensions. As for plastic - comic book bags work well too. They come in several sizes and can even been cut and reformed to make them larger or smaller as needed.

I like to store sheets with a glassine page between each sheet. That's how I would send them along with a stiffener. I raided an old album to obtain my cache of glassine sheets but I'm sure you can purchase them somewhere.

cereal/snack boxes

Great ideas. Thanks everyone

The glassine leaves sound like a good separator, and some sort of poly bag should keep any moisture getting in. I wonder if greaseproof paper could be a substitute for glassine material?

Chipboard (card) for stiffening - now that sounds like a great invention - I'll check out where I can purchase some of that.

I bid on and win a lot of sheet stamps and mini sheets.

Mostly the auction houses send them in plastic, binder sleeves that fit an A4 sheet and the stamp sheets are folded into them. Then they have thick, flat cardboard front and back. Have received up to 20 sheets with nothing in between them in the one plastic sleeve. Had 18 sheets arrive this week in the mail as described. It can rain and be a humid as you like but I hate it when they sit in the boiling hot sun for hours before delivery. I have to separate the sheets and let the gum set again before I can pack them away to make them safe.

Never had a damaged sheet or mini sheet yet! As I let the gum set again. This only happens with the local mail person!