Many a slip in paint­ing the roof

Canal Boat - - Back Cabin - TONY REPLIES…

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.

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