I use a normal pack of hand tissues, I made a large 1/35 tarp for a dio and worked a treat,,,,, mix PVA and water together so it's quite runny and then use a large brush to smoother it wait until its dry, then spray paint it as is easier then dry again, then when you have what you want, you then dampen it with water and drape it over the area and it goes just how you want it.....
I you google it then something should come up about a chap tarping his HET trailer and it looks amazing, I just followed his steps pretty much..
Lewis