Ghosting or something else

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pewe

New Member
Any suggestions as to why the rendering on a number of hoses would show large areas that seem to dry out more quickly/slowly than other areas on the same wall.
The patches are not distinctively block shaped (which is what I believe is called ghosting) and the size and number of 'wet areas' varies from house to house and is more/less visible according to colour.
All the houses were coated with Parex Monorex one coat system.
 

Rigsby

TPF Special Forces
There are several causes on one coat render. Different blocks, wet blocks, different suction in the substrate will give different setting times at the time of scratching back giving different texture giving different shades.

Was it raining shortly after finishing? Could be salts coming out, that can happen if the air is wet when it is hardening usually within 1-3 days of application.

Two different scratch pads can give you different shades.
 

pewe

New Member
My apologies I should have been clearer in my description of the situation.
All of the properties on the estate are between 4 and 3 years old - so the render has had at least 3 years to dry out. All properties were built of block and, I assume, the same blocks etc.
 

Rigsby

TPF Special Forces
Do you know what thickness the render is? You may find a horizontal Stop bead That will be either 10 or 15mm.
 

pewe

New Member
It is supposed to be 15mm minimum. However on our house there are bullet holes where the render has washed out to show the blockwork and the thickness varies between 8mm and 11mm using a tyre gauge. There are places where it looks thicker, so uniformity of thickness is an issue on our house.

The drying patchwork effect on the other houses leads me to think the other houses have the same uneveness of coating - however I am no expert, hence asking here.
 

Rigsby

TPF Special Forces
There are some Council houses near me and when it rains heavy you can see the blocks showing through. No idea how thick but they was hand applied about 12 years ago. They was originally Webers white but now grey.
 

church

Well-Known Member
Its different suctions on the block and muck joints and drying out times on the substrate ,
 
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