Ditto what BPA said.

Sometimes when I flew from low altitude to high, no matter now tight I closed a lid, some things just exploded. The expansion from the altitude change apparently wrecked the lid and made a mess. Now I put a bit of Saran wrap over the top and then tighten the lid as much as possible. Fingers crossed, I haven't had any problems since I added the extra step. Saran wrap, tight lid, zip lock.

I do the same as d_gw.

I use packable regulation size tubes, filled with my own products and have never had an accident with them inside the Ziploc bag.

I always double bag shampoo.

Yes, some things should be double bagged. It only takes one incident to learn that lesson!

Don't fill bottles full and double bag. If it leaks it leaks into the bag.

I use the plastic bottles from the container store. They work well. Just check that the lid is on tight.

I do a few things.

If I am carrying on, i just use the one ziploc and travel sizes of anything liquid go in there.

I assume you mean when you are checking a bag w cosmetics.

One, I put everything in waterproof travel cosmetic cases. I separate things that might leak (toothpaste, shampoo) from things that can't (deodorant, face powder, eye makeup remover pads etc). I don't usually pack any of the toiletries in with clothes. They usually go on their own bag with shoes (each in plastic bags), bathing suits, misc. Usually, that is all the precaution I need.

I have had problems in the past with certain items that would cause trouble. One was a pump face wash. The other was shaving cream. I used to put them in their own ziploc, but now I carry different products.

Nalgene travel bottles

GoToobs. I use the large ones for shampoo and liquid cleanser and such. Anything else I can't transfer into one of these gets put in ziplock bags and then into my waterproof cosmetic bag.

A piece of plastic wrap over an opening and then put the screw top on tight works well too. But I still put it in a ziploc bag to make sure.

I do use the ziploc bag and keep the liquids separate.

I always squeeze the bottle before tightening the lid so this way, if there is a small leak, it's the air want's to come in rather than the liquid seep out. If it won't hold the indent in the bottle then it is already leaking air.

I haven't had problems with flying (everything goes in a Ziploc bag though) but my worst explosions occurred while taking a short cut over Tioga Pass.

Now it's everything bagged even for car trips....

I use Go Toobs and double Ziplock bags. I also put a small dehydrated sponge in the bag. In case of a leak it will absorb the liquid.

I just double bag everything in ziplocks. My bag is usually very full so nothing has much room to move around. Once in a while I've had something leak but very rare and it's just a matter of cleaning up the bag and contents.

Well, this is timely. I am flying into Salt Lake City soon and forgot about the difference in altitude. I usually put liquids into travel size containers and then into a ziploc bag. Maybe I will take extra precautions on this trip. The absolute worst part of travel is packing. Yuck

Mtn, yes my concern is primarily for checked bags. We're in the midst of a long trip involving several flights. Due to the length of the trip I decided it wouldn't make sense to place everything in travel sized containers so am traveling with several full-sized containers. Some of the items (skin care products and RHT in particular) cannot easily be replaced while out of the country and spilling them isn't an option.

Marie-Cate, the sponge is an excellent suggestion!

Annie, squeezing the air out...great idea!

Thanks everyone!

I double-ziploc each liquid separately. No problems.