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Toxics Use Reduction Institute · Surface Solutions Laboratory
Toxics Use Reduction Institute

Surface Solutions Laboratory

Trial Report

Trial Number 1

(Client Number 341, Project Number 1)

Trial Purpose: To evaluate hard water stain removal

Date Run: 12/16/10

Experiment Procedure:
A good way to predict the effectiveness of an acid is by means of the so-called ?marble block? test method. This test is a good way to predict an acid?s performance under practical conditions.
To test the descaling performance, a marble block is submerged in a test solution for several minutes. The weight is measured before and after.

Several marble chips of similar size and shape were weighed to determine the baseline weight of each piece. The selected chips were then immersed in the products at vendor recommended dilutions and allowed to soak for 18 hours. The marble chips were removed from the products and rinsed in a tap water spray at for 1 minute to remove loose material from the chips. Then the chips were dried for 15 minutes using a Master Appliance Heat gun at 500 F. When the chips cooled to room temperature, final weights were recorded to determine weight loss, if any. Observations were made after the initial immersion of the chips into solutions (5 minutes), at 60 minutes and then following the overnight immersion.

In addition to the 4 products from the soil removal test, 2 additional products were included for hard water stain removal.

Trial Results
The current toilet bowl cleaner from TMI was by far the most effective hard water stain remover based on weight loss of the marble block and visual
observations. The PC 120 was the second most successful product from the previous trial. The two additional products, DFC Restroom and CLR, also were
effective at low concentrations. The table lists the amount of calcium removed from the marble and the observations on the process.

Product Initial wt   Final wt      Wt loss %Wt loss of block   Ave 
TMI Toilet Bowl
        16.9467      16.6224       0.3243        1.91        3.91
        7.1301        6.7089       0.4212        5.91        
Tough Job
        14.6607      14.6712      -0.0105       -0.07       -0.06
         9.8936       9.8993      -0.0057       -0.06        
7th Generation All Purpose
        20.2033      20.1934       0.0099        0.05        0.12
         7.1918       7.1781       0.0137        0.19        
        13.4153      13.3580       0.0573        0.43        0.33
         8.4230       8.4028       0.0202        0.24        
DFC Restroom
        19.8850      19.6572       0.2278        1.15        1.40
         4.8122       4.7330       0.0792        1.65        
        11.4138      11.3263       0.0875        0.77        1.19
         4.0115       3.9467       0.0648        1.62

Visual Observations                                
Product Initial        5 min        60 min                         18 hr
TMI Toilet Bowl
        Aggressive     mild        particles collecting on bottom  
Tough Job
        little        little/none  white haze                      particles collecting on bottom
7th Generation All Purpose
        none           none        none        
        None           none        little                          particles collecting on bottom
DFC Restroom
        slight         slight      none                            particles collecting on bottom
        none           none        none                            particles collecting on bottom

Success Rating
A follow up test, usually based on company input.

Additional marble block testing will be conducted to try and identify more effective alternatives to the current cleaning product.