plasticiser or not in a sand n cement render?

[kilty55]

hi all,,done a couple of sand n cement renders for a builder as of late ,im getting conflicting advice as so far i have put a touch of plasticiser in my renders which seems to give it a bit body and easier to spread but the builder told me there is no need for it? can anyone tell me the real reason plasticiser is used?

 

[smurf21]

http://en.wikipedia.org/wiki/Plasticizer
1ts purly for workabillity.

 

[david campbell]

plasticiser is used to allow air to move freely through when mixing,my old da is a brickie and they prefer using fairy liquid through it,if there isn't any plastiser,entrainent ,fairy etc the mix will seem lifeless and very tough to work with!

 

[sWe]

Many builders seem to think they know it all because they're "in charge", and that goes double for the type who wants to cut corners everywhere.

 

[doug boardley]

I always preferred lime to improve workability, thankfully don't do much plastering these days:hurray:

 

[Rob Z]

I never thought of using a plasticizer in wall mud before...the concrete guys use it to improve workability without adding water, but how does it affect mud for walls? Doug, we use masonry lime, as well.

 

[doug boardley]

to me Rob, if water rises to the top, it's not aerated (for workability, talking walls,) coming from a plastering background, I hate transferring a pile of unhomogenous mud from my handboard(hawk) to my trowel. It falls off my trowel!! lol

 

[mikethetile]

plastcisers break the water tension and allow the the water to permeate the mix thoroughly making the mix more workable

a dash of fairy works just as well but the nhbc insist on plastisicer.

i was taught to use lime

and yes you can use a dash to make render more workable if you wish

 

[White Room]

I would use plasticiser for what it costs, if fairy liquid is found in some render which has failed your liable. Pebble Dashing is good with lime

 

[Rob Z]

What is "fairy liquid"?