They work just fine.

George K

And here's an idea from Ross Lillistone's site that really works great:  Find a large can (like a coffee  can" and shove the unused freezer bag into the can and fold the top of the bag over the rim of the can.  This method holds the bag open while you're filling it with goo.  Try it, you'll love it.  Lowe's amd Home Depot sell empty gallon and quart paint cans that would also probably work.

The larger yogurt or cottage cheese containers work well for this and the goo doesn't stick to them. Don't make the corner cut too big or you'll get mile wide fillets like mine.

I used a freezer bag with a zip lock. It wasn't until I was squeezing the epozy down into the corner that I discovered the corner had an accordian fold to it. The epoxy squirted out in totally unpredictable ways. The suggestion about putting the bag into a can is a good one; try to get the epoxy as close to the corner as possible. The stuff that catches onto the sides of the bag is really hard to squish down to the corner. 

After two incredibly messy disasters with ruptured freezer bags, I switched to a much easier and neater alternative: I buy empty West caulking tubes, fill them with about six ounces of thickened epoxy and apply it with a regular caulking gun. With this method you can lay down a nice even bead very quickly. It also extends your reach by about a foot. -Wes

I always put a piece of clear packing tape around the corner of the bag to reinforce the corner I snip off.

Wes - I tried the West tubes but was unable to refill them.  What's your trick for pushing the "plunger" back out?  I tried wooden rods through the tip but they just snapped off.

Peter

Peter,

I use a metal rod. I also drill a couple of 1/16" holes in the plunger before using it. The holes are small enough that the epoxy doesn't come through them, but they let the air between the plunger and the epoxy escape.

-Wes

Thanks, Wes.  I'll try that on my current build (WD12 with MKIII Sail Rig).

Peter