Hi all,
Sorry to be a post w h o r e, but I'm struggling using materials that, when I first started doing a bit of building and rendering when living in Spain, I'm not used to.
Over there they just have one type of sand which is basically made by grinding down rock from mountains. It's white, very gritty and contains particles from dust size to 1-2mm size grains. Often needs sieving before it can be used for rendering, but when used, it's hard as nails - in fact the sand alone needs smashing up with a pickaxe if it gets wet and allowed to dry.
I found it nice to use and over 10 years of using it on and off meant I got very used to it. It produces a mortar that's a bit gritty but the dusty particles in it make a smooth paste which rises to the surface when floating with a bit of water to get a smooth finish, and it's fairly cohesive and sticky because of these dusty particles. Kind of like an ideal mix between mortar over here and plaster - best of both worlds.
Got 2 bags of sand from Travis, telling them it's for rendering. Seems to be soft sand (it's orange) and hard to render with, it just drags with the trowel and isn't sticky or cohesive. How do you render with this stuff?!
QUESTION IS HERE TO CUT THINGS SHORT:
Anyway, cut this essay short by saying I put my top coat over the scratch coat today and patches fell off while I was flattening it down after it'd stiffened a bit. Weird thing is that the chunks showed grey mortar from top towards the bottom, but 2mm from bottom, where the render was against the scratch coat, it was orange, all cement gone. Presumably this is why it fell away?
I dampened the wall well before doing the top coat and used a 5:1 mix. Is the problem this crappy orange sand that doesn't stick to anything, my rendering skills, or something else?
Sorry to be a post w h o r e, but I'm struggling using materials that, when I first started doing a bit of building and rendering when living in Spain, I'm not used to.
Over there they just have one type of sand which is basically made by grinding down rock from mountains. It's white, very gritty and contains particles from dust size to 1-2mm size grains. Often needs sieving before it can be used for rendering, but when used, it's hard as nails - in fact the sand alone needs smashing up with a pickaxe if it gets wet and allowed to dry.
I found it nice to use and over 10 years of using it on and off meant I got very used to it. It produces a mortar that's a bit gritty but the dusty particles in it make a smooth paste which rises to the surface when floating with a bit of water to get a smooth finish, and it's fairly cohesive and sticky because of these dusty particles. Kind of like an ideal mix between mortar over here and plaster - best of both worlds.
Got 2 bags of sand from Travis, telling them it's for rendering. Seems to be soft sand (it's orange) and hard to render with, it just drags with the trowel and isn't sticky or cohesive. How do you render with this stuff?!
QUESTION IS HERE TO CUT THINGS SHORT:
Anyway, cut this essay short by saying I put my top coat over the scratch coat today and patches fell off while I was flattening it down after it'd stiffened a bit. Weird thing is that the chunks showed grey mortar from top towards the bottom, but 2mm from bottom, where the render was against the scratch coat, it was orange, all cement gone. Presumably this is why it fell away?
I dampened the wall well before doing the top coat and used a 5:1 mix. Is the problem this crappy orange sand that doesn't stick to anything, my rendering skills, or something else?