Painting fresh plaster

jcb208

Dulus Fast matt is ideal for new plaster and drys a lot flater then some paints like dulux supermatt and is not chaulky either

cyclonebri1

DVardysShadow wrote: »

Do not use a dehumidifier to 'dry' new plaster!!!

It is a complete misunderstanding of plaster to do this. New plaster does not 'dry', it 'cures' - ie there is a process taking place which binds the water into the plaster chemically. If you use a dehumidifier, you are depriving the plaster of the time and the water it needs. Once the curing is well under way this process actually finishes by drying the plaster out, scavenging all of the remaining water.

Although I fully understand your reasoning and the principles behind what you are saying, I disagree.

Having seen the damage caused when heating was applied to a fully plastered out 3 bed house because of the amount of water still present, I have to comment.

The lower floor had to have 2 new chipboard floors as the newly replaced sheets absorbed so much water as to render them damaged beyond repairs, all the doors stuck, the skirtings popped off the wall in many places and stored goods were ruined.

I seriously suggest the op uses a dehumidifier on the job.

DVardysShadow

cyclonebri1 wrote: »

Although I fully understand your reasoning and the principles behind what you are saying, I disagree.

Having seen the damage caused when heating was applied to a fully plastered out 3 bed house because of the amount of water still present, I have to comment.

The lower floor had to have 2 new chipboard floors as the newly replaced sheets absorbed so much water as to render them damaged beyond repairs, all the doors stuck, the skirtings popped off the wall in many places and stored goods were ruined.

I seriously suggest the op uses a dehumidifier on the job.

Opening the windows for an hour or so several ties a day is more appropriate.

Why was the heating applied? It sounds like a different misguided attempt to dry the plaster out. Of course if you put the heating on, this will act as an ad hoc dehumidifier, reducing the relative humidity of the air and causing it to draw water from the plaster, but landing it in wood which itself is then lower on moisture than the air.

Left alone, the moisture would not have been so mobile to go away from the plaster and would have been absorbed by the plaster itself.

If goods must be stored in a newly plastered house, they should be stored in a dry ventilated room

cyclonebri1

I fully understand your argument but mine is fact. If a house is finished in say late Oct?, then the heating has to go on, the results are horrendous if water is not evacuated ASAP ie, dehumidifier,

DVardysShadow

The heating does not have to go on. The curing of the plaster actually provides some warmth. I don't doubt what happened, but the fact is that the ventilation and heating were mismanaged. I have had plenty of plastering done in most seasons and never had damp to that extent.

I imagine that you must have left the property heated and unventilated for at least 4 days. Once the plaster was dried - rather than cured, I imagine it was not receptive to the water, leaving plenty which the plaster would have absorbed free to damage woodwork.

cyclonebri1

If you move into a newly renovated BIG property in Oct, the heat does have to go on, sorry chap, just quoting experience and facts. The property was not left, I managed it, the water had to be removed.

Yep, plaster and concrete will set and cure best under water, but in reality it does ok in atmospheric conditions and that includes artificial drying