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Painting bare concrete blocks

HowlingGale

HowlingGale

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Any external painting experts around?

Got a bare concrete block wall in the garden that we need to paint. Getting someone in to do it is proving difficult as they're all busy so thinking of doing it ourselves.

Read online that it would need a mist coat. It also needs some fungicide at the bottom and we also need to remove some efflorescence with a suitable 'remover'. We're not sure if it will need a special undercoat or whatever.

What I can't find online is what order do things in.

My thoughts on the order are:
1. Efflorescence remover
2. Power wash walls and remove moss and 'live' stuff
3. Mist coat as apparently bare block is very thirsty
4. Undercoat with something
5. A couple of coats of sandtex or whatever

Am I miles off the mark with this?
Don't want to have to do it again next year.
 
Rlburnside said:
Seems your over complicating a simple job I would just power wash and give it 2 coats of masonry paint.
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No primer? That would seal the surface and prevent the masonry paint being drawn in. I haven't used masonry paint myself so perhaps it is substantial enough to seal and paint at the same time?
 
Lord Tyrion said:
No primer? That would seal the surface and prevent the masonry paint being drawn in. I haven't used masonry paint myself so perhaps it is substantial enough to seal and paint at the same time?
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That's what I read. It's more thirsty than dry plaster and that needs a mist coat. So many differing opinions. Don't know who's right.
 
HowlingGale said:
That's what I read. It's more thirsty than dry plaster and that needs a mist coat. So many differing opinions. Don't know who's right.
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I sell a specialist internal paint, I deal with a paint manufacturer. They will say every time to use a primer / sealer on a bare surface. This is particularly so for a surface such as concrete which absorbs heavily. You could end up applying 3-4 masonry coats if you only apply that.

For the sake of a tin or two of primer / sealer I would apply that and then the masonry paint. It may be slight overkill but with paint the old addage of 'do it right, do it once' tends to apply.

We had the outside of our factory unit paint last week. The wily old painter told me 70% is preparation, 20% is primer, 10% is the top coat. That is all you would be doing. Clean, seal, top coat. Break it down and it isn't that complicated.
 
Kill the moss by soaking with a ferrous sulphate solution. Leave for a week and remove the dead moss with a power wash or dry brush with a stiff scrubbing brush.

Posts #6 & #7

If the wall is not sun facing, every spring power wash off any green algae that has developed.
 
For the side of my garage wall I used a primer of white emulsion, PVA and thinned a little with water and then put in one of those pump sprayers that fence paint and the like goes in.
Two runs over of that with a 50% overlap spray and the job was a good un for rollering on Sandtex.

Whoever said Johnstone's is better than Sandtex is talking out their arse.

Johnstone's is cheaper for a reason, its rubbish
 
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Ive painted all 4 or the rendered walls of my garage 3 times in the last 24. All it ever has got is 2 coats of external paint each time after some small prep.
 
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