Recommend a primer for tiling plastered / painted wall?

[Gazebo]

if you must use tubbed then Bal white star would be my weapon of choice.....

 

[siremastimus]

Glad you said that Gazebo - ordered that one last night!

 

[ian158]

when you say gypsum, do you mean plasterboard ?, skim or bonding coat, ive used on all and found it sticks fine, open to opinions though, maybe you could advise what tubbed and cement based is good for, for my and any others future work.

 

[Ajax123]

when you say gypsum, do you mean plasterboard ?, skim or bonding coat, ive used on all and found it sticks fine, open to opinions though, maybe you could advise what tubbed and cement based is good for, for my and any others future work.

whe portland cement and gypsum are placed in direct contact with each other in the presence of small amounts of moisture (bare in mind your cement add is mixed with water) they react chemically and the calcium alluminates hydrate to become ettringite and thaumesite salts which are very soft and friable. The bond between the cement and gypsum are destroyed.

Plasterboard has a paper coating on it so the cement and the gypsum dont come into contact. You would normally use a primer to divorce the materials from each other on skim or finish coat plaster or gypsum floor screed. Without this primer the cement will not stick to the gypsum what ever you do.

Tubbed addys are not generally cement based but are acrylic dispersion and so do not eillicit this adverse chemical reaction. When tiling to Gypsum my personal weapon of choice would be a gypsum based adhesive if possible or a non reactive adhesive if not. Cement with a good quality penetrative primer would be my thrid choice followed by tubbed addy e.g Bal Whitestar which I used on my new fire place hearth tiled onto MDF yikes: ..... it is only decorative)

all adhesives have a place in the market. All adhesives are good if they are used as they are designed to be used What i get frustrated with is the attitude i often come across is that one adheisve is universally better than all the others and that is the one a tiler always uses............ i et the comment an awful lot that a tiler has been tiling for 30 years and has never had a problem then finds he has an issue in a given curcumstance and takes great offence when he is told that he has used inappropriate materials for a job. surely the materials and combinations there of should be selected based on their suitability for the application so you may use a whole range of adhesives for different jobs.

sorry I seem to have gone off at a tangent........

 

[White Room]

Quote; whe portland cement and gypsum are placed in direct contact with each other in the presence of small amounts of moisture (bare in mind your cement add is mixed with water) they react chemically and the calcium alluminates hydrate to become ettringite and thaumesite salts which are very soft and friable. The bond between the cement and gypsum are destroyed.

Walls were plastered for 40+ years used Sirapite gypsum plaster on moisture damp sand/cement without any problems ???

 

[Richard Edwards]

Nice one Deano - I would go one better -- Having faced this issue on three previous occasions, I deeply gouged the wall in a criss - cross pattern with deep scrapes about 25mm wide in a lattice and about 1-3 deep and then had a mamoth clean up. This provides a deep key to the plaster work below the paint, Then prime it with acrylic and tile - I prefer slow setting cement based but you can achieve perfectly good results with a quality dispersion ady like Bal / Nicobond / Mapei tubbed.
By the way 'wear a mask'

 

[phil w]

My head hurts ( not from new years eve) mucho confuso this adhesive lark

 

[ian158]

Yea, getting complicated

 

[Perry]

Quote; whe portland cement and gypsum are placed in direct contact with each other in the presence of small amounts of moisture (bare in mind your cement add is mixed with water) they react chemically and the calcium alluminates hydrate to become ettringite and thaumesite salts which are very soft and friable. The bond between the cement and gypsum are destroyed.

Walls were plastered for 40+ years used Sirapite gypsum plaster on moisture damp sand/cement without any problems ???

Thats a question i have always asked Mark never had an answer yet

 

[kingnewport]

what i do on a painted wall is the scratch the paint with a knife/nail anything. give it a good scratching all over and then use pva and water mix and paint the wall. Let it dry and tile away , the tubber stuff is ok for a few tiles but wont use it on a large area

 

[ian158]

Pva! Wait for it

 

[jay]

http://www.tilersforums.com/tile-ad...p-v-versus-primers.html?highlight=pva+primers

 

[kingnewport]

cheers for that :smilewinkgrin:

 

[The D]

what i do on a painted wall is the scratch the paint with a knife/nail anything. give it a good scratching all over and then use pva and water mix and paint the wall. Let it dry and tile away , the tubber stuff is ok for a few tiles but wont use it on a large area

:lol::lol::lol::lol: that's a good one.

 

[ian158]

Does anyone one use tubbed, I prefer to use cement based adhesives now