Fine stuff not turning out so fine

[fernicarry]

First time I've had a go with lime plaster. Nothing drastic just some damage repair prior to decorating, biggest so far is about 9" square, but with some larger areas still to tackle.

I got myself a bucket of Womersley's coarse stuff and another of fine stuff. The coarse went on without problem, indeed was quite pleasant even for someone like me with an aversion to messy wet stuff. The fine stuff is testing me however. It goes on well enough but dries to a very gritty finish that is crumbly around the edges. I just can't feather it in to the existing plaster the same as with a modern filler like Toupret.

Am I missing something or is that just the way it is?

 

[Lacan07]

First time I've had a go with lime plaster. Nothing drastic just some damage repair prior to decorating, biggest so far is about 9" square, but with some larger areas still to tackle.

I got myself a bucket of Womersley's coarse stuff and another of fine stuff. The coarse went on without problem, indeed was quite pleasant even for someone like me with an aversion to messy wet stuff. The fine stuff is testing me however. It goes on well enough but dries to a very gritty finish that is crumbly around the edges. I just can't feather it in to the existing plaster the same as with a modern filler like Toupret.

Am I missing something or is that just the way it is?

Well, its never going to be as smooth as gypsum but the lime putty based fine stuff I used didn't have a gritty finish at all, and I was floating an open textured finish which usually brings the sand to the surface. Did you sponge float the final coat? It may have bought some of the coarse sand to the surface.

Some of the traditionalists add chalk dust to their putty for a final coat, or you can just use lime putty straight as your final, final finish. I think you water it down first though.

 

[fernicarry]

Thanks. I did sponge it a bit to take out imperfections. Also been using a wet paint brush for the same which is what the directions say. The original plaster finish is as smooth as glass so I thought that's what I'd get from 'fine' stuff. Maybe as you say it was done with straight lime putty.

If the lining paper covers it without anything showing through then that's all that matters. I'm new to wallpapering too so I don't know what I can get away with.

 

[Lacan07]

Thanks. I did sponge it a bit to take out imperfections. Also been using a wet paint brush for the same which is what the directions say. The original plaster finish is as smooth as glass so I thought that's what I'd get from 'fine' stuff. Maybe as you say it was done with straight lime putty.

If the lining paper covers it without anything showing through then that's all that matters. I'm new to wallpapering too so I don't know what I can get away with.

Well I don't know which fine stuff product your using but I'm pretty sure I could have got a polished finish on my walls if I had the time and energy to fart about with it. Usually you float the finished surface up getting it quite wet and fatty and then immediately go in with your trowel to flatten and polish.

When I did one of my walls where quite a bit of the original plaster had just dropped off I used some base coat lime plaster I got free on FB marketplace. There were 8 bags of it so I used it for both scratch and float coat to get it ready to skim. Trouble is this stuff contained quite a sizeable type of stone in the mix and when I came to float the final skim coat up the stones kept coming to surface which I then had to laboriously pick out with the edge of my trowel! Lesson learnt that day = its best to use a float coat that has a finer grade of sand in it.

 

[noj]

Provided your finish coat is thicker than the aggregate it should be possible to flatten and polish (if your skills and energy levels are greater than mine).

Sponging will tend to leave a gritty surface since you are generally moving/removing the finest stuff and the aggregate stays in place. It does cover a multitude of sins though!

Some suppliers fine stuff is finer than others which makes the job easier.

Using chalk rather than sand guarantees a polished looking finish but amplifies every imperfection in your work.

Ultimately if it's getting covered with lining paper then a brush down once it's cured and it'll be fine. Alternatively a few coats of limewash helps

 

[malcolm]

I've had troubles plastering to an edge in existing plaster. You can't plaster over the edge as you just get grit on the existing plaster. A water spray and a sponge to smooth things out will wet the surface and bring some grit-free lime to the surface so you can get a smooth finish on the new plaster but still the join to the old plaster will be bad. I tend to use filler on the joint once the plaster has set.

 

[MatthewC]

If you want a smooth finish then you don't sponge the last layer, use a metal trowel. We used Mike Wye Regency plaster which is very fine and gave a great finish when done by an expert. I have had less perfect results - the edges are always difficult.

 

[overlander matt]

If you want a smooth finish then you don't sponge the last layer, use a metal trowel. We used Mike Wye Regency plaster which is very fine and gave a great finish when done by an expert. I have had less perfect results - the edges are always difficult.

We had a similar experience with the larger aggregates in Mike Wye Heritage. We ended up using it in the old staff rooms and boiler room where a rougher/textured finish was ok. The MY Regency is a lot smoother and in keeping with our property.

 

[fernicarry]

Thanks for the replies. Womersleys say the aggregate in their fine stuff is <0.5mm. I'm getting better results by not sponging and using a metal edge as recommended. Much less gritty than before. It is quite a faff working in small repair sections where you have to build up to the surrounding depth, I imagine doing a larger area is easier.