What type of paint should I use for stone painting meant for outside

Question

Not too long ago, my family’s dog was put down and we spread the ashes on one of her favourite (or so we assume) walkies routes. I want to create some kind of tombstone for her. I was thinking of painting a stone and then placing it at the side of the path.

Since the location is in the outside at the edge of a forest, the stone would be subject to weather influences: rain, snow, frost, sunshine. Naturally, I want the stone’s paint to survive these conditions. Also, wildlife may pass. I want the paint to be as harmless as possible to the surrounding nature.

What type of paint should I go looking for that satisfies the conditions highlighted in the paragraph above? And in case that paint may require specific handling, please also highlight some relevant points.

Answer 1

What you need is exterior masonry paint.

Which specific kind of exterior masonry paint may depend on what sort of stone you're using. This page from a decorating advice site tells you which kind of paint to use in which context. It's written from the point of view of painting walls of a building, but some of it may still be useful to you.

In particular, mineral-based or lime-based paint should fit your criterion of being eco-friendly, and limewash looks like the best choice for your situation: it's simple to make, relatively cheap, looks natural, and is eco-friendly. The following quoted text taken from the above link even provides you with possibilities for where to buy it:

Mineral Based Exterior Paints

Put simply, mineral paints are made with a silicate binder which reacts with the surface of the wall to form a long-lasting bond, unlike traditional paints which simply form a skin. They are naturally alkaline, so inhibit mould growth and carbonation; mineral paints also have the added advantage of being eco-friendly too.

The disadvantage is that they require more thorough preparation, special primers and are, initially, much more expensive – although the increased performance should pay back over the long term.

There are a few specialist manufacturers of mineral based paints – the main two being Keim and Beeck.

Each have their own detailed specifications for different kinds of wall surface and these must be followed to the letter in order to enjoy the maximum performance.

Lime Rendered Walls

For old buildings with a lime based render or lime based pointing a traditional Limewash is ideal. Limewash is simply a paint made from lime powder and water together with a colourant.

The main advantages of limewash are they bind to the surface very well and are totally breathable – another benefit is that they are relatively inexpensive.

Care needs to be taken with application and sometimes additional binders need to be added to aid adhesion.The finished result can be very striking though – looking much more natural than a traditional paint finish.

Limewash paints are available from a number of sources including Ecos, Ty-Mawr, Little Greene and Farrow & Ball.

ECO Paints

Technically, an ECO paint is simply a paint which has a very low or zero volume of Volatile Organic Compounds. While some ECO paints are obviously superior to others there isn’t any case for suggesting that an ECO paint will perform any better or worse than any other form of exterior paint – it will simply be a matter of personal choice.

It’s worth noting, however, that mineral and lime based finishes, mentioned above, are by their very nature eco-friendly – so would make a good choice if you wanted to be as environmentally friendly as possible?

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I also found detailed instructions on how to repaint a gravestone. They recommend using oil-based paint, assuming a granite headstone. If you're thinking more along the lines of smaller stones or pebbles, then this site recommends using acrylic paint, with a sealer on top at the end.

Answer 2

If you use transparent gloss paint to coat the stone after painting, it will

• look like polished
• you are very flexible in your choice of colour - the only constraint you have that your colour has be reconcilable with the gloss paint.

Answer 3

Honestly, painting stone is not recommended. Having it placed outside, moisture is the condition that will break the bond of any paint. Your specifications would call for a water based acrylic paint (aka "rubberized"). I would personally contact a monument company and see what they offer. Alternately, use a cedar board, painted (oil based is best) on all six sides, add black fine brush oil based for lettering. Stake it in the ground using "green treated" stakes. I had one on a cedar 1x12 last 20 years before it needed repainting. The monument company is your best bet, if you must have stone. Good luck!