Sand Jet Cleaning
We specialise in using a low pressure sand jetting system that has been used nationwide for property restoration, including gaining approval for and subsequently working on many Listed Buildings. The system, in our trained hands, 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 stone without injecting large quantities of water into the surface, and with minimal surface damage, at the same time, the 'damp' system also captures dirt and abrasive, preventing the health and safety risks associated with dry blasting. We would normally expect the sand jet systems to be around half the price of chemical stripping.
That being so, there are times when chemical stripping is needed. It can be considerably cleaner to use than abrasive cleaning, although generally the stripping solvents return paint to its liquid state, and therefore reintroduce the mess potential of paint. In general this is the technique to use for minimal surface damage. However as pressure washing is the most cost effective method for chemical and paint removal, some pointing etc. may be lost.
Test Patches on a Listed House in York, the top patch is sand jetting, the bottom a single application of chemical stripper. The sand jet has been more effective for one pass, but the chemical is causing less damage to the brick. It should be noted that the York Conservation officers did give the go ahead for sand jetting - and that is how the rest of the property was subsequently cleaned.
Paint stripping by chemical is much slower than abrasive cleaning, but conversely, in general, less labour intensive. The chemical is generally applied on one day, and washed off the next, but multiple applications of chemical may be required. A further data-sheet is here.
Subsequent cleaning with the sand jet can remove the final remains of paint.
Trial of Paint from Tiles in a Listed Grade II Cinema in Beverley
A set of photographs of a trial in a Listed Building cleaned in January 2005. The Glazed tiles would have suffered from abrasion if we had gone down the sand jet or dry blast route. Now I would consider Dry Ice Blasting, or even High pressure water jetting. The end result was that the entire surface has since been boxed and plastered in!
Napier's SARA stripping solution applied to the test patches, to remove the paint on the bricks, the tiles & on the glass (windows). Close up it looks as though someone has sneezed over a building. The chemical is environmentally friendly, is deactivated by water and is usually cleaned off with a pressure washer (although it can be scraped off with hand tools), however sheeting is placed on the ground to capture bulk paint and chemical debris.
After 24 hours this is what it looked like - the paint is peeling.
After the first pass with chemical, the paint on the glass and tiles has stripped off in one application (revealing that the windows are painted on the outside too!) while the layers of paint on the right hand side have separated, and a second application of chemical will be required.
Gloss Sealant from New Tiles
These tiles - on top of a new office block in Leeds (October 2005) had had linseed oil painted on to provide a gloss finish (that the customer didn't like)
Stripping Glue from a Stone Staircase
This staircase - part of Hull Central library, stripped of sealant and glue one winter - terribly hard work on our knees!
Listed Grade II Staircase
A listed Grade II staircase in Hull, we had sand jet cleaned 2km of wooden panelling (2m of which is in the foreground and background) but tests showed that we raised the grain too much on the spindles of this Oak staircase. So we had to strip it chemically over Christmas (and quite a lot of January) 2006 and 2007
Chemical Stripper Applied
- Effective on a wide range of paints, but a trial needs to be done first to confirm effectiveness! It is particularly poor on lime based paints.
- Chemicals used are environmentally friendly and are deactivated by water
- Definitely the method to use on softwood surfaces
- Very effective at cleaning paint from metal surfaces - although as no surface profile is formed, so it is not suitable on its own for surface preparation for cold galvanising.
- Excellent for graffiti removal from glass, plastic or wood where sand jet would cause damage,
- Cleaning to the requirements of BS 8221-1&2 :2000 the British Standard Code of Practice for Cleaning and Surface repair of buildings.