Thatching: The Appliance of Science

I just wanted to do a quick post to share a tip with anyone thatching their buildings with towels as I have done. If you're not sure how to go about thatching your building in this way, you can read all about how I set about the task here. What you end up with is something looking a lot like the photo above.

Trouble is, a this stage the building is crying out to be painted.  But you can't.  Towel, by its very nature, is going to suck up anything wet that comes near it.  That includes your lovely paint.  If you don't manage to find a way of stopping nature taking its course, you'll end up going through heaps of paint and ending up with something akin to a very cheap decorator's roller.  A swollen, sodden mop of a thing that looks nothing like thatch at all.

This is why you need to soak the towel in a mix of PVA and water. This will soak into the toweling and seal the material so you can paint it.  When this stage is done the fabric should be pretty well sealed and won't soack up tube after tube of paint. Plus, by applying the mixture with downward strokes of a large brush, you can convince the towelling to lie down the right way.

Most people who do this will tell you it takes a couple of days to dry out.

Mine didn't. It was dry and solid within 24 hours. Let me share with you what I did.

Wet water.

I know it sounds silly, but you can actually buy the stuff from model shops. I'm not making this up.  I didn't buy any because there's a much cheaper alternative in your home already.  Washing up liquid. If your hobby project ever requires some, just add a small drop of washing up liquid to some water.  It's that simple.  It'll probably smell nicer as well!

So if you're following this method, you'll need a 60 / 40 mix of PVA glue and water. Then you add to this a drop of your washing up liquid. Mix it together thoroughly and apply it to your roof using downward strokes of your brush. You want to get it thoroughly wet.

So how does this work?

It's all down to hyperphysics; in this case, surface tension. Water is made up of hydrogen and oxygen. The former has a positive charge, the latter is negative. It's the natural attraction of these molecules on the water's surface that forms the meniscus or surface tension .  The active ingredient in your washing up liquid of choice is a reductant which breaks down the surface tension of the water you squirt it into.  This enables the water to be absorbed more easily.  This is how it breaks through grease and dirt.  So, by adding some washing up liquid to your PVA and Water mix, you are effectively helping the liquid to soak into the towel more easily.  This means you don't need as much.  Which means your roof is less likely to warp with all that water hanging around. And this in turn means it will dry more quickly.

Mine did.  And they are rock solid.