Float & set - which option?

[kjacko]

Hi all,
I’m keen to have another go at float & set, but in the current climate where gypsum products are as rare as rocking horse doo doo, should I got for a sand and cement render rather than hardwall (which I’ve been using and since ran out of)?
The walls are back to brick but with no cavity, just double skin brick (built in 1902). I’ve been told I should NOT use dot’n’dab because of this, although the outside of the house has been treated with some thermal render type stuff, so it would probably be ok.
That said, I want to have another go at float & set.
I’m guessing 25kg of sand/cement would be cheaper than a 20kg bag of hardwall at £11.
What ratio mix should I use?
Should I put additives like lime, or plasticiser in it?
Would a paddle mixer suffice for sand/cement render?
I want to get about a 10mm render coat, and then skim as per usual.

Any and all advice appreciated.

ps....it’s my brothers house, so I’m kind if using it as a project for improving my skills.

 

[dontbelieveawordofit]

4 or 5: 1 (building sand) with sbr mixed in a mixer.
start top right corner if your right handed at a level 10mm and work your way down and across .
by trowelling into where youve already been you should be able to maintain a relatively uniform thickness.
(use the back of the trowel to remove high spots as you see them)
soak the wall first and keep wetting it as you progress, or sbr the wall before starting.
get yourself a 4” polyurethane float with 2 or 3 screws just proud to scratch and level it up as you go.

or , batten it.
or , pile it on and darby it flat.