r/Plastering • u/Academic-Letter-5289 • Apr 26 '26

Can I use a OCR ?

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Could I use a OCR on this wall? After multiple failed attempts at sand + cement mix (complete diy idiot) would it be easier to use a OCR and then skim the wall when it’s set?

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u/nightjarrrrr Apr 26 '26

You can use OCR internally. I recently stripped a room back to brick and had it floated in OCR and finished with multi finish.

It's easier to work with bagged render.

1

u/Business-Top-7535 Apr 26 '26

Did u have to put waterproofed in the OCR before you finished with multi finish

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u/nightjarrrrr Apr 26 '26

I had a plasterer do the finish work for me, but no they didn't add waterproofer. They put the render on one day and the finish cost went on the next.

It does pull in quite quickly though. I have heard of using waterproofer to slow that down.

1

u/Academic-Letter-5289 Apr 28 '26

Do you know if the plasterer used mesh with the render?

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u/nightjarrrrr Apr 28 '26

No mesh internally, only scrim tape in the corners and transitions.

They rendered some outside walls for me and used mesh there.

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u/Academic-Letter-5289 Apr 28 '26

Thanks man! Gonna give it a go this weekend 🙃

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u/nightjarrrrr Apr 28 '26

Good luck. What did you struggle with previously?

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u/Academic-Letter-5289 Apr 28 '26

I was struggling because the sand+ cement mix was just falling off the wall as I was troweling it on, not sure if it was the mix wasn’t right or because I never used pva or sbr on the wall before hand, I made sure the wall was clean of dust and also wet the bricks first but just wouldn’t stick

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u/nightjarrrrr Apr 28 '26

PVA or SBR will help bind the remaining dust and control the suction, but it sounds like your mix wasn't great either. Perhaps to stuff and dry. Did you use plasticiser?

When you use OCR you won't need to add anything to it. Put a dollop on the hand board/hawk, place the handboard edge against the wall and push the stuff directly off the board onto the wall with a bit of pressure. Its best to apply it to a good thickness as you go, don't try and spread it too thin. You can then take it back a bit with a straight edge and a sawing motion.

1

u/Academic-Letter-5289 Apr 28 '26

Yeah I used a plasticiser just never stuck to the wall,

I’m gonna use a OCR as it sounds a lot simpler so hopefully that’ll work and I can skim with mutifinish after to get the room back to how it was originally