Depends on the contents - bigger aggregate will help reduce cracking on a thick pass. As will fibres/hair/hemp. If you chucked a thick coat of fine top coat on with very small aggregate, it will likely crack.
- Thread starter aockenden
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Lacan07
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Well, I'm not saying I hit those targets exactly, as I'm sure you know plastering is an instinctive art. For me it was guide so I concentrated on applying more material in shorter strokes with minimal pressure. I have no idea why experienced the few cracks I had but I'm sure it was not dryness and to be honest I'm not sure thickness was the reason either. I've also had the odd crack when skimming old lime and I'm guessing that probably was something to do with suction because old lime needs loads of watering.
Have you had issues with cracks on wood fibre at your place than? What plaster are you using?
I’ve taken the corners off my stainless trowel. Catching edges bothered me too much, nothing I have is truly plumb and that’s fine by me.In this particular case I already had a Venetian trowel, just not in the same location as I needed it so rounded off a cheap old one I had knocking around rather than spending money doubling up on a tool I already had just for a couple of days work
Just a radius of a few mm made all the difference.
But to be fair, I’ve given up on polishing anyway, too much effort and not the right aesthetic. Plus an open face helps with the going off and i find better for applying limewash/distemper.
wood wool is quite forgiving I’ve found, mechanical key, no suction, so you just have to be mindful of the environment to go off nicely.
Fine mix, thin top coating over original daub, now that was a needy beast! Didn’t matter how much I’d damped the daub the few days prior, it all cracked to varying degrees. They was a lot of spraying and sponging…!
fernicarry
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I've just done part of a wall with wood wool boards and Breathaplasta products (NHL based which I know is not to everyone's taste). They recommend 2 universal coats at 4mm and two smooth coats at 1-2mm each. The universal has hemp fibres in it. I wanted to minimise the build up to match the existing level so I just did one base enough to cover the plastic washers and scrim tape them moved on to to the two smooth coats so probably about 6 or 7mm total. It dries really fast, problematically fast for a novice like me as by the time I came back around to try to polish it most of it was already too hard. No sign of cracking after a few days.
We just did our first coat onto our cork boards (with taped board-joints). Everything is looking ok so far. It went on yesterday. But my wife scraped it on pretty thin, maybe 2-3 mm thick, and I’m wondering what effect that’s going to have.
This first coat is self-mixed: 1 part lime putty, 1 part NHL 3.5, 2 parts fine sand, 2 parts fine hemp shiv.
Going to do a second pass without the hemp, aka 1 part lime putty, 1 part NHL 3.5, 2 parts fine sand.
Here’s how it’s looking today.
Ok that’s very similar to the approach we’ll be taking. Good to hear no problems were had.
Lacan07
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I reckon that'll be fine, obviously NHL sets stronger than non hydrated lime as you know so will be more susceptible to movement. This is probably a mute point though as nearly all wood fibre manufacturers specify NHL with their products (usually Lime Green Solo). I can't see how cork will be any different.
When I did my first wall I used heritage putty plaster (non hydrated) and no issues so far. I just find it way easier to work with.
Lacan07
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100% agree, I found it has zero suction. The main issue was waiting for it to go off to attempt a polish, it tuned out to be in the middle of the night!
I assume you don’t dampen-down your wood wool before plastering it?
Definitely not! It’s Weetabix! Unlike woodfibre boards which can manage moisture a bit, the wood wool boards don’t deal with getting wet. There’s also zero need, it’s all mechanical key.
Yeah ok makes sense, thanks.
Lacan07
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