How can water based varnish be water repellant?

I may be being really thick about this, but if a varnish is water based(i.e you have to clean the brushes with water)how can it then be water repellant when it’s dried? Sorry about this but it has me scratching my head, and I need someone much more knowledgable than me(just about anyone)to explain it.

Your skin is water-based and that’s water repellant…

Rachel

Basically, it’s science.

the long chain molecules that make up the varnish form from smaller, water soluble ones as the varnish dries. there will be chemicals that induce this in the mix. It’s called polymerisation (same mechanism as superglue).

Some stuff ‘dries’ where the water evaporates out of it. Then you can just add the water back again and it’s the same as it was before. Some stuff undergoes a chemical reaction ie ‘cures’ and becomes waterproof.

Concrete is powder mixed up with water, and ends up very much waterproof. that’s because it doesn’t ‘dry’, it sets. A chemical reaction.

Car paint is also now water based. Says on in the rain quite well!

Just like Teflon coating, how do they make it stick to the frying pan.

bigrich and molgrips-I bow to your supreme knowledge. Thank you.
Rachel-After Thursday’s soaking ride, I’m not sure my skin is waterproof. I swear I weighed another stone when I got home!
And finally…Jamie-You the man!!

I’m not sure my skin is waterproof.

It’s not it’s semi permeable, sit in the bath for about 30mins for a demonstration.

the long chain molecules that make up the varnish form from smaller, water soluble ones as the varnish dries. there will be chemicals that induce this in the mix. It’s called polymerisation (same mechanism as superglue).

Like I said, science.

You didn’t tell him to concentrate Jamie.

Me: Why should I?

Drac: Because he’s worth it!

Ahhhh man you spoilt it b

Party Poopin’ since 1979 8)

It’s not it’s semi permeable, sit in the bath for about 30mins for a demonstration.

By the power of Science!

http://www.nature.com/news/2011/110628/full/news.2011.388.html

Let the varish dry on the brushes. Then try washing them…

The hypothesis, from Mark Changizi, an evolutionary neurobiologist at 2AI Labs in Boise, Idaho, and his colleagues goes against the common belief that fingers turn prune-like simply because they absorb water.

Err! I’d have guessed as scientist they’d have known about osmosis and absorbing water would make the skin go tighter not wrinkle. Seems I may have guessed wrong.