Calico on roof. While in Albury at the end of August we also picked up several metres of calico and chose a slightly cloudy day to roll the calico roof on. We didn’t want it drying out too quickly. We had washed the sizing out of it in a hot wash and spent 2 hrs crawling round the floor ironing the wretched thing. Calico wrinkles terribly when washed. We then rolled it up around a large cardboard roll to keep it as flat as possible. If we folded it, there would be creases. So with two tall ladders and one of us on each side we put about a metre wide layer of undercoat and sealer on the roof and proceeded to unroll and stick the calico to the roof. Once we got the first two metres done, it became easier. We ducked inside the caravan occasionally when we got to a skylight. Given the size of it, we didn’t do too bad a job wrinkle wise and no joins. Another 2 or 3 layers of undercoat and sealer and then two top coats – tight as a drum and leak-proof. When we bought the stuff we hadn’t measure the distance so made a rough guess and added some for shrinkage and a bit for luck. I think we had 10 centimetres left at the end to cut off. After the roof was finished, and the calico was trimmed, the caravan’s edges were lined with aluminium J-mound and the sail rail was added for the awning. The roof skylights were also added and covered with tinted Perspex.
Last Edit: Oct 26, 2020 21:24:13 GMT 10 by tooleyau
Post by shesgotthelook on Oct 27, 2020 11:23:16 GMT 10
We did our little Globe with Calico from Spotlight. No pre washing. put undercoat on roof, rolled calico on, stapled one corner & pulled across, stapled other corner & pulled tight, then stapled all edges. Liberally applied water with paint rollers.(yes water!) When dry,cut excess off, put 2- 3 layers of undercoat (I'm struggling to recall exactly) then 2-3 layers of top coat.
In respect to "Dope". Typical doping agents include nitrocellulose, cellulose acetate and cellulose acetate butyrate. Liquid dopes are often highly flammable; nitrocellulose, for instance, is also known as the explosive propellant "guncotton". en.m.wikipedia.org/wiki/Aircraft_dope
Highly flammable is the important factor.
As to using, or not using canvas or calico. The calico acts as a bonding material that holds the thick layers of paint together. Along the lines of reinforced concrete.
You are probably right that you could use paint only as most caravan sides are only painted BUT, and I think it's a big but, where the timber joins you need something more than just paint to prevent leaks. If you look at the sides on timber caravan you will find fine cracks in the paint at the joins in the timber as this is where the two sheets of timber move because of expansion and contraction (hot and cold) and thus the paint cracks. Calico prevents this on the roof - where most water sits.
However, having said that I am sure that someone could provide a more technical explanation.