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Trial Number 13

Trial Purpose:

To determine how well products work on hard water stains.

Date Run:


Experiment Procedure:

To test the descaling performance, the marble block test method was used. In this test, a marble block is submerged for period of time in a test solution. The weight is measured before and after. Marble is chemically similar to hard water stains in that they both are made up of calcium carbonate. Results can be expressed in grams lost over time. This method is widely used due to its simplicity but has some restrictions. One such limitation is how other soils typically mixed with hard water stains are not taken into consideration.

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 two supplied products at vendor recommended dilutions and allowed to soak for18 hours. The marble chips were removed from the products and rinsed in a tap water spray at 120 F for 3 minutes 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 and photographs were taken after the initial immersion of the chips into solutions (5 minutes), at 60 minutes and then following the overnight immersion.

Trial Results:

The two supplied products all should signs of removing the calcium from the marble block. The two comparative products had less obvious changes. The non-acid comparative product resulted in a net weight gain over the 18 hours of soaking, although only minor in magnitude. For the supplied all purpose cleaner at various dilutions, the most dilute solution was the only dilution that performed significantly lower than the comparative product. 

Product Marble piece Initial wt Final wt wt loss/gain % change
PC 116 small 9.4224 8.6152 0.8072 8.57
  large 22.3224 21.2112 1.1112 4.98
PC 120 1-64 small 6.6252 6.4836 0.1416 2.14
  large 26.8356 26.6639 0.1717 0.64
PC 120 1-128 small 10.8646 10.8489 0.0157 0.14
  large 34.4596 34.2204 0.2392 0.69
PC 120 1-256 small 14.3193 14.2733 0.0460 0.32
  large 38.6275 38.5665 0.0610 0.16
3M 19 small 7.9570 7.9644 -0.0074 -0.09
  large 26.4420 26.4470 -0.0050 -0.02
Lav Safe small 7.3452 7.2906 0.0546 0.74
  large 36.4784 36.4173 0.0611 0.17
Water small 14.0765 14.0728 0.0037 0.03
  large 35.3339 35.3237 0.0102 0.03

Summary by Type of Cleaning Product

Average wt loss

PC 116 non acid bathroom cleaner 6.77
3M 19 non acid bathroom cleaner -0.06
PC 120 1:64 1.39
PC 120 1:128 0.42
PC 120 1:256 0.24
Lav Safe 0.46
Water 0.03

Success Rating:

A follow up test, usually based on company input.


The two supplied products had the greater weight loss over time when compared to conventional products of the same field of cleaning products.

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