Stone.
Surface Preparation – Nationwide
Dirty and Painted Stone Cleaning
Greenleaf Contractors offer a stone cleaning service across the UK. We clean stone with a variety of methods or options, from superheated steam (DOFF type techniques) moving up (in aggressiveness) to our sand jet machine, through sandblasting or grit blasting, and up to high pressure water should you desire it (and assuming that your stone can stand it – we won’t necessarily go out of our way to damage your stone unless you REALLY insist!
We can simply clean dirty stone, or strip paint from it. Post treatment we can seal the surface to prevent discolouration in the future. We typically work in Yorkshire, Nottinghamshire and Lincolnshire, but regularly travel to London, Derby, Newcastle and Scotland.
Before anyone worries – all the pictures on this page reflect work done with our Sand Jet machine, unless stated specifically otherwise! We have not, for example, cleaned York Assembly rooms (the photo below) with a dry blast system!
Sand Jet Cleaning
Greenleaf Contractor’s low pressure sand jetting system has been used nationwide for property restoration, including gaining approval for and subsequently working on many Listed Buildings. The system causes minimal damage to an underlying surface and is flexible enough to tackle most property restoration cleaning tasks.
The low pressure sand jet can clean bricks without injecting large quantities of water into the surface, and with minimal surface damage, at the same time, the ‘wet’ system also captures dirt and abrasive, preventing the health and safety risks associated with dry blasting.
As you can see by the picture on the right, surface dirt is removed with minimal (if any!) damage to the underlying stone. The low dust or steam cloud in front of the operator alsoi allows us to see very precisely what we are doing – much easier than Superheated Steam or even Dry ice cleaning.
Dry Ice Blasting
There are times when alternative methods are called for, one of which is Dry Ice blasting. Here a surface to be cleaned is blasted with solid CO2 particles, and the surface is cleaned through thermal shock, the massive volume change as dry ice particles turn into gas, and some abrasion of the surface contaminant, making the process ‘grit or sand free’.
The advantage of this system is that the ‘abrasive’ evaporates on impact, so the only ‘debris’ is the material being removed. It is nearly ‘dustless’ – about as dustless as it is possible to get for an open blast system – however it will still blow cobwebs, birds nests, paint debris etc. fairly liberally!
In this example we were using it to remove soot from a fire damaged church tower – and one of the advantages was that we were able to blast directly at the glass.
Traditional Dry Grit or Sandblasting
90% of the time Steam or Sand Jetting will do the job – but the damp nature of the blast does mean that the abrasive and removed dirt / paint stick to surfaces – this can be washed out, or left to dry and brushed out. But we have now re-discovered that old fashioned, traditional dry blasting can, if the operator is careful, be quite effective at cleaning internal stonework, so we now offer that service as well. It is one of those ‘swings and roundabouts’ things – the dry blast will use more abrasive and create lots and lots of dust, but is perhaps a little easier to clean up on the day.
This photo on the right was a mill floor in North Yorkshire. Sand jetting a floor is tricky because the damp abrasive gets in the way, whereas when using a dry system it just gets blown everywhere!
Superheated Steam Cleaning
Although we specialise in using a listed building approved variable pressure sand jetting system which causes minimal damage to an underlying surface and is flexible enough to tackle most property restoration cleaning tasks.
That being so, there are times when using an abrasive system may be more than a substrate can cope with, and low pressure superheated steam may be the answer. It is generally slower, and less messy, and can be quite effective for surface contaminants such as algae and grime. Subsequent cleaning with the sand jet can remove stubborn stains.
In Aberdeen we removed Lichen and moss (and grime) from the old Customs house almost in the centre of the city as it was converted from an office block to residential use.