How much in a Minimix 150?

I'm reading (now) that for render a 1:4 mix is too strong anyway. And then i've done 1 bag of cement to 4 bags of sand which puts me at

Classic - do a job then research it later!

I've tended to count shovels when mixing so volume. Someone with more experience may be along shortly.

the reverse.

solid cement is water impermeable and sets hard as a rock. The more sand you add the more likely once over about 2:1 there is to have porosity - air gaps - in the final product.

Render - like most other cement based products - is 'as cheap as we can get away with' . 4:1 is weak but won't actually fall off...and when doing mortar for brickworks, there isn't much point of it being less porous or stronger than the bricks are.

Only when you start adding in ballast - stone - to make a strong waterproof slab do you want to ensure that all the gaps between the stones are full of sand and all the gaps between the sand are filled with cement...

Sand/cement basecoat for plastering is even weaker.

ISTR that it used to do a 5:1 mix without a problem when it was new. And I am talking your 25Kg bags.

Of course it has been abused over the years.

I never tested it before I dropped it off at yours.

To be fair it looks in better nick than most of the stuff on ebay and the like.

It's usable (if not abusable) so mega grateful. :)