Normal Techniques for Masonry
The basic technique established over many years has five stages carried out in order:
1. To pre-wet.
2. To degrease and prepare the surface for the acid cleaner.
3. To power jet off the surface debris.
4. To clean using the appropriate acid-based product.
5. To power jet off the surface debris.
The purpose of pre-wetting is to fill the pores in the masonry and mortar with water so as to prevent deep chemical absorption and retain the agent on the surface where its cleaning action is needed and from where it can be removed more efficiently later.
A cold-water jet is normally used and each square metre of surface washed and wetted for about 30 seconds after which a short time is allowed (5 – 10 minutes) for surface water to drain down. This jetting also removes dust and loose organic matter from the masonry face. This should be carried out on all
types of masonry except prior to using organic solvent-based paint stripper or silicone water
repellent or solvent based degreasers.
Therefore, specially designed primer mortars are available for the restoration mortars. The Remmers Primer Mortar ‘soft’ also has salt accumulating properties.
Surface Preparation & Degreasing
Prepare your walls properly before using an acid cleaner for the best results
If this stage is omitted, then the efficiency of the acid-based cleaner will be reduced and the results may be patchy. Heavy black surface carbon soiling may require repeated degreasing treatments or extended contact times and this will be evident from the first test patch trial. Care would be necessary regarding the contact times on sandstone etc. Hydrofluoric acid containing chemicals left on the surface of some masonry, for long periods, can lead to colour changes or to white deposits forming. Only weak acids are necessary for neutralisation on clean masonry or calcited stone.
For cleaning exterior masonry, we recommend a selection of one of the following:
These agents can be applied on any type of pre-wetted stone, brick or concrete etc., as shown in the table, following the safety precautions given in the individual product data sheets.
Thickened (viscous) products are applied by brush and worked well into the surfaces leaving an even and thick coating of the product.
Non-viscous products can be applied by low pressure spray units but considerable additional dangers are involved and so spray application is not a preferred technique.
Quick Clean is a concentrated, alkaline, low odour, non-caustic, anti-static cleaning and degreasing agent for hard surfaces.
Quick Clean has a rapi~ wipe off cleaning effect and is totally phosphate free.
It is not viscous like HD400, with care it can be applied by spray. It is a special formulation for the breaking down and removal of black carbon dirt, oils and greases from any masonry surface.
766 Limestone & Masonry Prewash
When used properly, the prewash dissolves and assists in removing heavy carbon encrustations from brick, terra cotta, sandstone, limestone and most other masonry.