Can any of you guys advise me how long I should leave a newly rendered concrete wall to cure before painting it?

I understand it should not be allowed dry out too quick, because curing (a chemical reaction) needs to draw on the water in the mix.
Thanks

a month, in that case act quick if applying final coat, as rainy season shall be approaching soon. i was going to simply say, as 1st reply, 'before it rains', but since now have an informative answer, i can now be a smart-arse.

Consider using an oil-based primer under the top coat. The top coat can also be oil-based to last longer.

It is a wise idea to "water" the wall a couple of times a day for a week or so, stops it drying out too quickly & cracking...

Thanks guys.

My research suggested 4 weeks, though many Internet sites talk about concrete floors and probably concrete laid in UK/USA. The locals here want to do it after 3 days and only seem to understand concrete "drying", wheras it actually "cures" by a chemical reaction within, and as Bob says that needs water to complete the process. So I think it shouldn't be allowed to dry out too quickly.

I have done a lot of commercial maintenance on industrial property here in the UK which included replacing broken and spelched concrete hard standing for HGV vehicles. As we have very damp weather the curing time that we allowed was five days before any vehicles could run on it.The thickness is a major factor also when you talk about curing.These days there are many additives that are used to speed the process up.The hot climate of Asia would be a totally different approach. I have seen on my travels concrete pouring on highways in midday sun in Thailand with scree ding off using a plank for a smooth surface then trowelling off afterwards. I have never been stuck in traffic long enough to see the finished product on there previous days work so i cant comment what it's like.All i can say is if the concrete drys out too quickly it will crack and be totally useless.Water needs too be applied frequently to prevent cracking whilst being shaded from the sun.

BobHelm wrote:It is a wise idea to "water" the wall a couple of times a day for a week or so, stops it drying out too quickly & cracking...

Good advise Bob. Concrete cures with a chemical reaction depending on the grade of cement product used.
Sand & Cement mix for render needs at least 3 weeks to go off properly before painting but as Bob said soak at least twice a day to stop cracking, I would soak for 2 weeks then let dry naturately . Use a good primer ,2coats before finishing with at least another 2 coats good paint.
This advise is for Thailand in the UK you dont need to soak it manualy it comes natural.

Yes, I'd agree with the above. You should have seen me stood outside with a watering can, watering some new concrete (a couple of times a day for a week) a few months back. I'm sure the local builders thought I was a bit loopy. Though if they knew their job, they should know what's involved and why!

I have sometimes seen newly cemented concrete piles wrapped in polythene (to keep the moisture in and to prevent the concrete curing/drying too quickly). I think they knew what they were doing.