[quote="Simon and Jen" post=57453] Use Silver Sand, bought from a builders merchant, recommended by my father with a lifetimes experience in the painting business. [/quote] ...and as I suggested way back, put it in a sock to get a fine, controllable distribution. A kitchen sieve is too coarse and easily creates lumps.
I ue Sandtex masonry paint on my decks. Makes a nice nonskid. Its available in lots of places online. I had it delivered from the UK to France in three days. It has held up fine for three years. Any nonskid is more difficult to keep clean than gloss paint. On our cabin tops, we put a coat of gloss over the second coat of nonskid to make cleaning easier.
Probably more expensive than some of the options mentioned here but I have bought International's Interdeck from Ian Noble at Moissac and the chandlery in Gruissan in the last 12 months. Stockists also in Toulouse and Beziers. Jon Zee Otter
Why do people pay a premium price for 'non-slip' paint when they can just sprinkle sand on their favourite make of paint? My experience of ready-made non-slip paint is that it's just paint with the sand already in the tin, needs ferocious stirring to get the sand well-mixed - and still gives an uneven grittiness. Sprinkling fine sand on top of the penultimate coat of plain paint is so much simpler and cheaper and can give a better result.
Guess what I'm doing next week! With Sigmamarine paint, silver-sand and an old sock. (the last two came with the boat)