BlueVac Captive Head-Washing System

Salt reduction & desalination of the masonry

The principle of the captive-head washing system (originally “Gregomatic”, now “BlueVac Low-Pressure Captive-Head Washing”) is a combination of a targeted water whirl, which produces a rinse action, together with a simultaneous vacuum action to remove dissolved or loose residue from the substrate. The system can also be used to rinse off bacteria (mould), low & high pH detergents, oils, fire damage soot and other contaminations from all washable surfaces including fibres (carpets). This patented system awarded Gold Medals at International Inventor’s in Geneva, Basle (Switzerland) and New York (USA).

Sketch of BlueVac System

BlueVac Head-Wash Tool

Manufactured and redesigned in Australia by Let's Clean Pty Ltd

The captive-head washing system has been shown to successfully remove the residue of a “Cocoon” type of desalination poultice without increasing the water load in the substrate.
This raised the question of whether the captive-head washing could also be used for the desalination of the masonry.
To answer this question, test samples have been conducted.

A. On a dry surface (without pre-wetting) with captive-head washing; and
B. By pre-wetting the previous day using de-ionised water to mobilise salts, followed by captive-head washing.

Results

Captive-head washing after pre-wetting with de-ionised water (B) produced a significant salt reduction, not just on the surface, but up to a depth of 10cm. There was no movement of salts further into the substrate. The salt reduction was greatest in the first cm, declined with depth. Results obtained with captive-head washing are comparable with those obtained by traditional poulticing procedures. Where the substrate was not pre-wet (A) the salt reduction was less significant.

When using captive-head washing purely for its cleaning/rinsing action (to remove the residue of chemicals or other contamination), the moisture content of the substrate has not risen, which means the negative pressure (i.e. vacuum) of the wash head is greater than the capillary effect of the substrate.

Other Test Patches have been conducted on Natural Stone and Render type of surface for Sulphate content. Core samples were taken of up to 10cm in depth, before and after captive head washing.

  Building Surface         
    Before     After 3x
wash cycles
    After 6x
wash cycles
 
  Natural Stone M%              
  Area one 0.24     0.061     <0.01  
  Area two 0.15     0.067     <0.01  
                   
                   
    Before     After 3x
wash cycles
    After 6x
wash cycles
 
  Render M%              
  Area three 0.24     0.25     <0.05  
  Area four 0.15     0.25     <0.05  
                   

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