Basing Methods?

[darthgus]

While not snow on its own, taking some of the clear plastic from blisters or even old jewel cases cut to fit can be easily frosted over with a bit of superglue

Its a good tip for making a frozen water / ice sheet base.

I had a friend many years ago who built an ice table for 40K. He built a large ice sheet out of frosted glass. A bit extreme under most circumstances but looked great.

[sundayhero]

For my own hobby use, I tried bicabornate. I made some tries using artist gloss acrylic heavy gel instead of PVA glue, the result is nice (a bit "wet" perhaps) and for now it's not yellowing or changing. I don't how long yellowing usually appears.

The sample figure I based is staying under french south west sun all day, with no problem for now (I don't know if the yellowing is caused by UV or moisture?).

For my commercial scenery I bought Noch/woodland scenics snow flakes. I never used it before, we'll see.

[darthgus]

Home made bases and treasure tokens... see my blog for a step by step.

[Malebolgia]

Bicarbonate
My tip: stay away from this method. I did in the past and all of my snow yellowed after 5-6 years, even with white paint added to the mix. I think it is due to highn moisture, as it all happened after I moved house and my new hobby room was noway as dry as my first one.

My favorite: crushed glass
Yes, it's glass...and yes it's a bit more tricky. But the end results are very good, and it stays white. But that also depends on the binding medium (glue/water effects) you're using! So make sure you're not using a cheap white glue that yellows over time.
Here's a tutorial I wrote for Scenery Workshop's blog on their Crushed Glass product:
http://blog.sceneryworkshop.nl/2013/02/crushed-glass-scenery-workshop-tutorial/
(yes, it's Dutch, but Google Translate should help...and of course I can answer questions ).
Some examples with crushed glass:
http://paintoholic.nl/images/valkyrie.jpg
http://paintoholic.nl/onewebstatic/8fbf7cf9c3-images-drago.jpg
http://paintoholic.nl/onewebstatic/582ff324d2-images-valachev2.jpg
http://paintoholic.nl/onewebstatic/5ab57b7780-images-vlad2.jpg