One of the chores that confronts me every time I arrive at the house is sweeping up all the dust that has fallen off the walls. The "paint" used out here is extremely friable, so the slightest touch - or brushing it as you walk past, causes a fall of white powder. Even without any outside assistance, small flakes regularly fall off the walls. While it can be a pleasant, relaxing end to the day: sitting quietly with a glass of wine, listening to the paint flake off, the clean-up and ever expanding patches of bare concrete means that this is not a satisfactory situation. Something must be done.
I started looking into how to redecorate the inside of the cave-house towards the end of 2006. The rewiring early in the year had meant chasing out channels in the walls to run plastic conduit to contain the power cables and more disruption where I added new sockets (there were lots of new sockets - about 50 in all). This, plus the vibration of the building work had given the walls a good shaking and loosened the cal where work had been done.
Add to this the inherent instability of the material, which the spanish reckon to repaint every couple of years and you have a large undertaking and then continual maintenance every year or two.
This is the same material that is traditionally used to cover the outside of houses too. You can see my views on that in the painting the house article earlier. An extra complication on the interior walls is that they are not waterproofed.
Since a cave house is dug into a hillside, the walls are essentially the rocks and earth of the hill (or as in my case, that rock with a concrete layer on the inside). Without "tanking" or a waterproof membrane, there is scope for any damp in the earth to seep into the house. Fortunately, the locality is quite dry, with no standing water and the sheer thickness of material means that there is virtually no scope for water to get in. However, like almost every house's basement, the level of damp in the walls is higher than conventional paints are designed for.
Over time I have been carrying out little experiments with various materials to find one that is suitable for painting onto the walls in this environment. I have one particular section of wall which seems to be the most prone to dampness and this has been my test-bed, on the assumption that if something will stick to this wall, it'll stick to all of them. Generally, I've been applying a finish to parts of this wall on each trip over. Then, some months later I'll check to see how it's holding up. Until recently all my trials have resulted in failure, with the material flaking off, bubbling up or going soft and turning to dust.
I've used paints that are (so called) interior paints, "breathable" paints, "plastico" (in reality, vinyl emulsion) paints and exterior paints. I've followed the advice of others and their recommendations, I've ignored the advice of people who tell me that I should be using "traditional" methods and materials and I've come up with a few ideas of my own. Some of these preparations start off looking promising, but none of them last more than a few months before they start to show signs of deterioration. I was starting to run out of possibilities, when my glance fell on the patio wall I had erected two years earlier. This was exposed to the elements: searing heat, freezing cold, rain, wind, frost and more snow than we ever get in britain. It was also made of blockwork, without any damp-proof course. Yet having been subject to all this for 2 years, the white mortar I had finished it with was still holding up. The brain cell went into overdrive: if it'll stand up to outside conditions, it should work indoors, too.
So, in early 2008 I made up a test batch of mortero blanco, also called capa fina, with a little white emulsion paint added to brighten up the white colour of the mortar and to make it a little more spreadable. On it went, to the wonder-wall and back I went to the UK. 6 months later and it was still in the pristine condition I had left it in. As an added bonus, it also fills in cracks and gaps and can be applied thicker to help lessen some of the smaller variations in smoothness of the walls.
As I write this, it's 2009 and I have recently come back from a month's stay in Spain. In my later visits in 2008, I started applying this goop to sections of wall in the living room - having spent many more hours preparing the walls than it took to repaint them. Since these main walls had all come out OK and withstood the damp of the winter, I completely redecorated the living room and hall (the two rooms in most need of attention) with a good, thick, coat of paint / mortero mixture.
Here's looking forward to a dust-free future.
