Exterior painting

[moguk]

The previous owner of our house rendered it with an extremely rough finish.
He then painted it with a very dark colour, and we are told it looked so patchy when he rollered it that he then spent many days up the scaffold using a brush to 'stipple' the paint to get it to look right.

We want to change the colour but no matter which roller I use the dark shows through all over the walls.

I do not fancy getting in the scaffolders then spending days 'stippling'.

I have an HVLP spray system but the paint needs quite a bit of thinning to spray with it - about 1 part water to three parts paint.

Anyone had any experience of the results of using watered-down masonry paint.

 

[johnny2007]

Use sandtex brilliant white.
The dark colour will go after 2 coats.

 

[opps]

The previous owner of our house rendered it with an extremely rough finish.
He then painted it with a very dark colour, and we are told it looked so patchy when he rollered it that he then spent many days up the scaffold using a brush to 'stipple' the paint to get it to look right.

We want to change the colour but no matter which roller I use the dark shows through all over the walls.

I do not fancy getting in the scaffolders then spending days 'stippling'.

I have an HVLP spray system but the paint needs quite a bit of thinning to spray with it - about 1 part water to three parts paint.

Anyone had any experience of the results of using watered-down masonry paint.

Unless you have a 4 or 5 stage HVLP with the correct needle, I would not recommend trying to spray masonry paint. You could possibly hire an airless sprayer with a lance?

Photos would help.

 

[moguk]

Use sandtex brilliant white.
The dark colour will go after 2 coats.

Using Sandtex - but it's Plymouth Grey. It's not the number of coats, its the size and depth of the 'holes' in the render that are so small and deep that the roller can't get paint into them.

Unless you have a 4 or 5 stage HVLP with the correct needle, I would not recommend trying to spray masonry paint. You could possibly hire an airless sprayer with a lance?

Photos would help.

I have a 3 Stage Fuji HVLP (1600W) - but it doesn't seem to be powerful enough to blow the paint. Not sure of the nozzle size, but a 2mm drill bit easily fits the hole in it.

 

[opps]

Using Sandtex - but it's Plymouth Grey. It's not the number of coats, its the size and depth of the 'holes' in the render that are so small and deep that the roller can't get paint into them.



I have a 3 Stage Fuji HVLP (1600W) - but it doesn't seem to be powerful enough to blow the paint. Not sure of the nozzle size, but a 2mm drill bit easily fits the hole in it.

I too have a 3 stage Fuji (it predates the Q series). I normally only use it to spray acid cat (which is extremely thin).

I now understand what you mean about the depth of holes. You could try to heat the Sandtex to make it easier to atomise. Floetrol (or propylene glycol) will also help (plus a little water). Assuming that you don't have a gravity fed gun, you can keep the lower part of the suction cup in a bucket of warm water. Will the 30ft hose be long enough though (if you plan to work off a ladder)? I use 2 lengths of 30ft hose so that I can keep the turbine as far as way as possible. I hear less noise and the air entering the gun is cooler. I use a remote control socket to turn it off and on.

 

[sparkwright]

Using Sandtex - but it's Plymouth Grey. It's not the number of coats, its the size and depth of the 'holes' in the render that are so small and deep that the roller can't get paint into them.

Use a brush then.

And fill any 'holes' that are too deep to get a brush in, if there are any.

 

[moguk]

Use a brush then.

And fill any 'holes' that are too deep to get a brush in, if there are any.

Thank you for your 'contribution'.

 

[moguk]

Just to close this topic, I have found the answer to my issue and have tried it on one 24 sq metre wall with success - no 'pitting' and all done in just over 2 hours.

Thanks to those who contributed.

 

[opps]

Just to close this topic, I have found the answer to my issue and have tried it on one 24 sq metre wall with success - no 'pitting' and all done in just over 2 hours.

Thanks to those who contributed.

Glad to hear (read) but what was the answer?

 

[moguk]

I bumped into a fellow dog walker the other day and he happened to have over 20 years of rendering and painting experience.

He said that the problem with 'thinned' masonry paint is that it leaves a very thin coating when the water evaporates or is 'sucked' in.

He told me to roller it first, then spray with a coat of paint thinned to a level that the sprayer would accommodate - then when dry to overcoat with a second roller coat if it looks patchy.

As it turned out, the finish wasn't patchy after the spray coat so didn't need the second roller coat.

I used a 12" roller from the ground using an extension pole for the roller coat, then the fuji sprayer off a ladder to finish.

The wall is 6 metres long 2 storey with no windows/doors to worry about and I 'cut' in the edges at the top whilst up the ladder spraying.

 

[opps]

I bumped into a fellow dog walker the other day and he happened to have over 20 years of rendering and painting experience.

He said that the problem with 'thinned' masonry paint is that it leaves a very thin coating when the water evaporates or is 'sucked' in.

He told me to roller it first, then spray with a coat of paint thinned to a level that the sprayer would accommodate - then when dry to overcoat with a second roller coat if it looks patchy.

As it turned out, the finish wasn't patchy after the spray coat so didn't need the second roller coat.

I used a 12" roller from the ground using an extension pole for the roller coat, then the fuji sprayer off a ladder to finish.

The wall is 6 metres long 2 storey with no windows/doors to worry about and I 'cut' in the edges at the top whilst up the ladder spraying.

Well done, BTW, with regards to the the "thinned" coat- adding floetrol is not considered to be "thinning", they (the manufacturers) call it "fortifying". Although it sounds like marketing BS, it is true given that, unlike water, it doesn't actually "thin" the paint.

Waterbased paints cure through coalescence, as the water evaporates off the molecules shrink back and bond (knit together). In your case, the water would not suck in to the substrate (becasue it was previously painted), but too much water would effect the "knitting" process.

Thanks for the update, I may consider using my Fuji for wall spraying at some point in the future. I always found that using it for water based finishes on cabinets was unacceptably splattery but for rendered walls that won't be a problem.

Many thanks