Many a slip in painting the roof
I want to paint the roof of my boat and keep it non-slip. I did it about five years ago and someone recommended sprinkling a fine sand on it while the paint was still wet, brushing off the excess when dry and then top-coating it.
This looked okay at first but, eventually, it started to lift and it was impossible to patch it up to make it match the original, so I have removed all the sanded areas. Rather than use a textured non-slip paint, someone has told me of a very fine powder that can be added to the paint that stays suspended in it and gives a good non-slip surface. Do you have any idea what this powder is? Someone thought it could be crushed walnut shells or fine crushed glass.
Although the roof was well sanded using an orbital sander, some areas are still showing the old paint lines so I’m after something that would help cover the imperfections made by the old paint lines.
It has had a couple of good coats of filler/undercoat but although this has helped, the imperfections are still slightly visible. I don’t want to go to the lengths of sanding it all off back to bare steel or the expense of sand blasting the whole of the roof. Any suggestions would be greatly appreciated.
QWhen my boat was painted I used Protectacoat which has ground-up rubber granules in it and, since then, it has been refreshed with oil-based floor paint and latterly an eggshell finish oil-based paint.
The paint on the tops of the rubber granules seems to wear off so you retain the non-slip but the surface tends to look a bit grubby after a while. This has been in place for more than ten years.
Hemple sell non-slip powder for mixing into paint so I am sure the other major suppliers such as International will do the same. It is vital that you do not exceed the recommended dose rate, I guessed and ended up with paint that took weeks to dry. I think
Athe material is fine plastic powder. If the old paint only lasted five years or so it might be the preparation was deficient; incompatible primers could have been used, or there might have been a problem in application.
You talk about two coats of filler/undercoat, but normal body filler is porous, as is primer, so if it has been exposed to the environment then, at this time of year, it is likely that water will have soaked into the paint.
Whatever you do you can expect paint problems unless you can dry it out in some way. If you are painting outside, you might have to give it a holding coat of top coat and wait until the summer when you can sand the top coat off, let the paint film dry in the sun and then continue with the paint system.
If the old paint film has lifted, those areas would have been taken back to base metal and the paint edges feathered really well but I see no mention of primer, only undercoat. However well you feathered the edges, they are likely to still show through unless you use something like a high build primer-surfacer to fill the low area and then sand back with fine abrasive paper. This is why boat painters prefer to take boats back to bare metal. I suspect you might be stuck with the lines unless all the paint is taken off. Unless you are in a heated paint dock, this is not the time of year to be doing this. A high gloss paint shows such defects more readily than a matt surface so using a semi-matt paint like the ‘Raddle’ colours from Craftmaster or similar may make them less noticeable.