Float Coat Blown In less than a Week

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iron

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Hello all Im looking for a bit of help please. My Scratch Coat was a 5:1 mix, Top Coat 4:1. The sand did seem far too fine to me but wasnt sure if it would make a difference. Plus I was using a combined additive ( plasterciser, waterproofer and something else I cant remember now, It was 3 in 1 thing) ..I usually use waterproofer and thats that!! .. Float coats blown and the scratch is still stuck but very sandy ( New breezeblock Wall ).. Am I safe to add the Top Coat and try again seeing as the scratch is dusty? Removing the scratch now would be a nightmare. Thanks

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You've got the sand/cement ratios the wrong way round mate - top coat should always be weaker than the one before it:RpS_thumbup:
 
Plus by the sounds of it your scratch coat didnt cure properly this happens when you top it too soon try soaking the scratch coat down for a couple of days that might harden it but if it dont then take it off and start again.
 
Thanks all. I'll give it a soaking and add the lime to a 6:1:1. The scratch had 3 days drying time and its only really the one wall thats blown, the rest of the walls the paint hasnt taken too well due to the sandyness ( is there such a word I dont know? ) ..The sand was terrible though, plus Im not using that crappy 3 in 1 additive again! I need to get this order right which sand would you all recommend please?
 
Last time I used it it was shiiiiiiiiiiit couldn't cream it up at all and used loads of lime I'd be stuck from know on I've never used anything else
 
Personally I always use Everbuild 3:1 additive in my first coat. Getting a scratch coat to cure properly is not about just leaving it long enough to dry, you need to keep it moist for the first two to three days to allow the cement to fully set and cure slowly.
Now that you have a powdery scratch coat I'd suggest that you try wetting a small area and then using a nail or similar scratch a small hole to see if the scratch coat has soaked the water right through to the blocks. If it has then a good soaking with Jewsons masonry stabiliser or similar should harden it of. However if the waterproofer has worked even though the coat hasn't cured then well you're ******. I would only use the above remedy on fairly small areas, on anything sizeable or elevated I'd just take it back to the blocks and start again.
 
There is some good advice there, it does sound as if the scratch coat was a bad mix, it should not be at all sandy, if it was my job I would have to remove most if not all of it back to the brick or stone and replace with a good strong scratch coat and leave to cure. far better than trying to get away with it when you could have major problems in the future
 
essexandy said:
Personally I always use Everbuild 3:1 additive in my first coat. Getting a scratch coat to cure properly is not about just leaving it long enough to dry, you need to keep it moist for the first two to three days to allow the cement to fully set and cure slowly.
Now that you have a powdery scratch coat I'd suggest that you try wetting a small area and then using a nail or similar scratch a small hole to see if the scratch coat has soaked the water right through to the blocks. If it has then a good soaking with Jewsons masonry stabiliser or similar should harden it of. However if the waterproofer has worked even though the coat hasn't cured then well you're ******. I would only use the above remedy on fairly small areas, on anything sizeable or elevated I'd just take it back to the blocks and start again.
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maybe he should have used my mate micro.......
 
Waddington fine wash,which is quarried where i come from.It is a well graded sharp sand not your river shite which can have to much silt content.scratch coat 4-1 Integralwaterproofer,leave to cure for a few days.Second coat 5-1.also don't use wet sand as it will have bulked.
 
Secret is contoling suction mate. Use a liquid called pva, it makes the background stickier and seals the bricks
 
@ twitcher .
You may have used sharp sand which had little stones in it. It's meant 2 be used for floor screeding mate . Try using soft washed sand
 
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