We have had a couple of low retaining walls built in the garden using shuttering (M400 and stone) 10cm wide.

 

Thai style mix!  So am wondering how long before I can paint them, as inferred plenty of water in the mix. In the UK it would be at least one month.

From memory this time of year if the wall gets a lot of sun I would just prime it with a couple of coats and do 2 full coats later on in the year when it's cooler. 

6 minutes ago, Kwasaki said:

I would just prime it with a couple of coats

Primer coat needs to be about 80% thinner. The thinner soaks in and takes the pigment with it rather than the pigment just drying on the surface.

2 minutes ago, VocalNeal said:

Primer coat needs to be about 80% thinner. The thinner soaks in and takes the pigment with it rather than the pigment just drying on the surface.

How do I suck eggs.? ????????????

17 minutes ago, Kwasaki said:

How do I suck eggs.? ????????????

Poke a hole in one end, then...????

40 minutes ago, PFMills said:

We have had a couple of low retaining walls built in the garden using shuttering (M400 and stone) 10cm wide.

 

Thai style mix!  So am wondering how long before I can paint them, as inferred plenty of water in the mix. In the UK it would be at least one month.

Short answer, immediately the surface is dry (3days) using the correct paint.

 

Longer answer; there are 2 kinds of paint one is designed to be used immediately the surface is dry enough and is an alkali resistant one. The other is the same kind as you would use in the U.K. where the concrete render has to be cured for over a month.

 

All paint shops and most big stores with a specialist paint department will tell you which paint is OK for fresh concrete.
 

From experience using the correct paint with correct thinning you get a perfect durable finish, I do not permit the top coats to be thinned, if the painter insists he looses the job, my money, my paint, my way.

Follow the manufacturer's instructions exactly.