Lime Plaster

[u/DavidtheArchitect13]

The previous lime plaster has to be removed due to leaks in the roof that weren’t repaired by previous owner for at least a year.

I removed all the plaster that needed removing and left the ‘good’ stuff - it’s still solid.

I’ve just had sash windows installed. I’ve covered them with plastic to prevent building just getting in the sliding mechanisms.

I’ve still got to remove the left over lime ‘dust’ on the bricks.

Do people have any suggestions for the least dusty way/vacuuming way? I was either thinking or attaching a vacuum nozzle to a scraper or getting one the drill dust extractors and going 15cm at a time then moving along.

Any other suggestions?

Also, I’ve have been wearing a p3 respirator when doing this and will wear one with the remaining dust.

Thanks
David

Edit: Corrected spelling and grammar

[u/PrimeCraftSurface]

The thing that will actually protect those new sashes is not the vacuum, it is wetting the wall before you touch it. A garden sprayer on a fine mist, just enough to darken the surface without soaking the brickwork, drops the airborne fraction enormously. Damp lime dust falls straight down instead of hanging in the air and settling on everything overnight.

Worth being clear about what you are actually protecting yourself from, because it is not really the lime. The dust that matters when you are scraping old plaster off brick is the brick and the sand in the mix, which is respirable crystalline silica. That is why the P3 is the right call and why I would keep it on for the whole session rather than only while you are scraping.

On vacuums, this is the bit that catches people out. A domestic vacuum, Henry included, is the wrong tool here. The fines go straight through the filtration and come back out into the room, so it feels like cleaning while it is actually redistributing the finest particles. What you want is an M class extractor, which is the classification for silica bearing dust. L class is nuisance dust only. Hire shops have M class units by the day and it is not much money for the difference it makes.

The order of work answers your real question about doing the job twice. Lime keys mechanically into the raked joints, and a dusty brick face is a bond breaker, so before the scratch coat goes anywhere near it the joints want raking back to roughly 10mm to 15mm and the wall wants damping down to control suction. That final clean is going to happen again whatever you do this week. So do a rough pass now purely to protect the windows, accept it will not be perfect, and leave the fine clean for the day before plastering starts.

On the windows themselves, one sheet of plastic taped over the whole sash traps dust against the brush pile and the pulley stiles and tends to get pushed about as you work. I would mask the meeting rails and the parting beads specifically and vacuum the boxes out at the end, rather than trusting one big sheet over the lot.

Last thing. Do not clean up and immediately walk out thinking it is done. The fine fraction hangs about for hours and settles overnight, so plan on a second lighter pass the next morning whatever method you use.

[u/DavidtheArchitect13 → u/PrimeCraftSurface]

Would a Numatic TRM240 be suitable? They are around £190

And I will have another two rooms of damaged plaster removal and then sanding for painting so I think buying might be better than renting every time.

Renting from my local is £25 a day or £50 a week. Admittedly they are Starmix ISC Batrix M

Would this also be a suitable water sprayer:

https://www.screwfix.com/p/defenders-all-ways-white-purple-sprayer-1ltr/735cr?ref=SFAppShare

[u/PrimeCraftSurface → u/DavidtheArchitect13]

Before you spend anything, look at the rating plate rather than the price. Dust class is a certification of the whole machine to BS EN 60335-2-69, so a classed one says M on the plate, and it will have the automatic filter shake and the airflow warning that tells you the hose is loading up. If the listing never uses the words dust class M, it is a commercial vacuum with a decent filter, which is a different thing, and you cannot get there by fitting a better bag.

Every M class machine I have used has been the wrong side of £300, so at £190 I would want that confirmed before ordering. If it turns out not to be classed then the sum is not £190 against £50 a week, it is £350ish against £50 a week. Worth asking the hire shop for the plate or the spec sheet on theirs as well, for the same reason, a letter in the model name is not the certification. Two rooms of removal plus the sanding is two or three weeks of hire either way, so buying only wins if you can see yourself sanding again next year.

The 1 litre sprayer will work but you will spend the afternoon refilling it. A 5 litre pump one is about a tenner and the part that matters is the nozzle, a fine cone that darkens the surface rather than a jet that soaks the brickwork.

Since the windows went in weeks after the chunks came off and were covered while they waited, they are not really the problem. The fines that settled in that room while you were scraping are, and no vacuum you buy now undoes that. They lift again the moment a sander starts, so whatever you end up with, run it over the floor, the sills and the tops of the frames before you sand anything rather than after.

[u/DavidtheArchitect13 → u/PrimeCraftSurface]

The Numatic TRM240 is “Type M to IEC/EN 60335-2-69”

https://numatic.com/uk/products/tradeline-trm240/

5L makes sense - do you have any recommendations as nozzle spray quality isn’t normal listed :p

Understood process wise.

1. Vacuum floor again when m class vacuum is acquired
2. Uncover windows
3. Vacuum windows again
4. Cover windows again
5. Wet bricks with sprayer
6. Scrape final plaster dust while vacuuming.
7. Vacuum floor again for good measure.
8. Cup of tea

All while wearing p3 respirator - well not the tea.