Question: What’s more tedious than watching paint dry? Answer: Waiting for a dry day so you can put the paint on in the first place.

Or, to be closer to the truth, waiting for a dry day so that the guy you’ve hired to do the painting can get on and finish it.  Getting the outside of a house in Waikato painted in May always had ‘stupid idea’ written all over it. It should have been done earlier in the year, but, for various reasons, it slipped to April, and then it was the Easter holiday, and then it started raining, and, about a month later, it’s still not quite finished. Hopefully, when I get home tonight, the scaffolding will be down and it will be all done, but, given the showers that have been marauding through the region today, I have my doubts.

Anyway, since paint is at the forefront of my mind at the moment, it’s worth a comment on just how much science is in it.  Water-based emulsion paint is fascinating – what is most perplexing is that the  paint uses water as a solvent so you can apply it easily, but dry paint keeps water out. There’s lots of physics and chemistry going on with regard to how the components of the paint work together so that it does what it should. Getting paint to dry nicely without cracking, rippling, blistering and so on needs a bit of experience, as I’ve found out in my own efforts at painting, and is basically why I get someone else to do it. (Plus I’m not going up on ladders/scaffolding to do the high bits.) Certainly one thing is to make sure the surface is dry before you start – otherwise water can get trapped underneath which doesn’t do the wood much good and, once the sun gets on it, will cause the paint to blister as the water underneath evaporates and pushes up the dry skin of the paint.

Therein, of course, lies the problem. Where does one get a couple of dry days from in May?

I’m not a paint expert, but a bit of browsing throws up some quite nice articles on what is happening with paint. For example, here’s a nice easy-to-read one from Harvard. The message: Interesting physics is everywhere. 

Have a good weekend.

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