wavy lines and fig 8s scratch and finish only in 12.5kg bags

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Four quick (possibly daft) questions...

1) Why is the scratch coat finished in horizintal wavy lines, but the float coat finished in shallow figure of 8s...is it more to do with diffrentiating between the two so somone doesn't inadvertantly skim a scratch coat?

Also some of the pics I've seen here, the figure 8s are very sparse...can't be providing much of a mechanical key??

2) I can only get finish plaster in my local shed in 12.5kg bags...is this normal? (They have hardwall, bonding, board finish, multi finish etc in 25kg...)

3) Does Finish Plaster provide a MUCH better finish over multi finish? is it worth worrying about as a beginner?

4) I've used a sikaflex slurry waterproofer before to seal a damp penetrated wall (cured the leak first!)..but was expensive per tub...is there a more cost effective way to replicate this using sand cement and SBR/Waterproofer. Got the plastering bug noew and want to seal the lower parts of a dmap old garage before plastering...

Cheers,

Virgil.
 
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Teh figure of 8 is to encourage you to 'cut' and 'close in' the floating rather than just rub over it and close it. The keying itself is only really relevant if you are doing sand and cement or your floating is closed in tight. Most gypsum float coat has enough rough areas for finish to stick to.

And it was also a way of saying ' I can float properly' :)

If someone inadvertently skims a scratch coat, the problem is not the pattern of the lines!
You need to get 25kg bags for economy.
Multi or board finish is fine, but I fond the multi not nice lately.

Sealing the damp wall may not be the answer - what is the cause?
 
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Another thing with scratching a scratch coat with wavy horizontal lines is ease of drainage.If you scratchcoat with straight horizontal scratch lines,when you wet the wall down, the water will not drain from the wall easily,, it will lay in the scratch lines. With wavy scratch lines the water will run/drain off of the wall much easier.
 
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Teh figure of 8 is to encourage you to 'cut' and 'close in' the floating rather than just rub over it and close it. The keying itself is only really relevant if you are doing sand and cement or your floating is closed in tight. Most gypsum float coat has enough rough areas for finish to stick to.

And it was also a way of saying ' I can float properly' :)

If someone inadvertently skims a scratch coat, the problem is not the pattern of the lines!
You need to get 25kg bags for economy.
Multi or board finish is fine, but I fond the multi not nice lately.

Sealing the damp wall may not be the answer - what is the cause?

Thanks. Damp is coming in from soil stacked against one wall and a hole in the wall doesn't help :) the other wall from a tree branch that had punched a hole in the wall...both cured now!

Checked the gypsum site...you can get 25kg bags of multi and board finish, but only 12.5kg of 'finish' ...seems strange...and not just my shed being useless for once...
 
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Another thing with scratching a scratch coat with wavy horizontal lines is ease of drainage.If you scratchcoat with straight horizontal scratch lines,when you wet the wall down, the water will not drain from the wall easily,, it will lay in the scratch lines. With wavy scratch lines the water will run/drain off of the wall much easier.

So a criss cross hatch pattern scratched in with a trowel will work well in draining the water off...glad to know ;) (dont have a big 'afro comb' and didn't get round to making one...)
 

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