Field of the invention The invention relates to a composition for cleaning hard surfaces. In particular, the invention relates to a composition comprising calcium-based anionic surfactant.

Background of the invention Hard surface cleaning compositions are available in various formats. There was a time when powders were widely used. Then came bars which were shaped like soap bars. Bars are being gradually replaced by liquids and pastes. Abrasive pastes usually contain an anionic surfactant, generally sodium salt of linear alkyl benzene sulphonic acids, as well as a non-ionic surfactant and an abrasive.

It is observed that the pH of such cleaning compositions is often very high due to the presence of sodium carbonate (soda). Therefore, they are harsh and not generally recommended for use on substrates such as Sunmica™, a brand of laminate. This led to the rise of milder cleansing compositions that have close to neutral pH.

Calcium and magnesium salts of alkyl benzene sulphonic acids provided alternatives to the sodium salts which has been used for several decades. Usually sodium salts are prepared by neutralizing the corresponding acids with soda ash or sodium hydroxide.

The surfactants which are calcium or magnesium salts of linear alkyl benzene sulphonic acids (Ca-LAS and Mg-LAS respectively) are milder. They are effective against some of the more common stains. When it is desired to prepare calcium or magnesium salts of alkyl benzene sulphonic acids in bulk quantities, usually calcite (i.e. calcium carbonate), magnesium carbonate or other equivalent alkaline substances are used to neutralize the corresponding precursor sulphonic acids. Dolomite is an alternative neutralizing agent which results into a mixture of Mg-LAS and Ca-LAS in varying proportions which depends on the concentration and type/grade of dolomite. Some amount of magnesium sulphate and calcium sulphate is also generated which act as in-situ structuring agents in cleaning compositions, especially dish wash bars.

Indian patent application IN225/MUM/2000 A (Hindustan Lever Ltd, 2005) discloses neutralization of LAS-acid with Dolomite. The reaction products, i.e. Ca-LAS and Mg- LAS, serve as surface-active agents in the hard surface or laundry detergent compositions disclosed in this publication.

It is observed that there is significant variation in the proportion of calcium carbonate and magnesium carbonate in dolomites of different grades which depends inter alia on the place from which the dolomite is mined.

Therefore, whenever dolomite is used for neutralizing LAS-acid, the proportion of Ca- LAS and Mg-LAS also varies accordingly. While minor variations are acceptable, a major variation can have adverse effects on the performance of the end-use cleansing compositions.

WO2014/044639 A1 (Henkel) discloses aqueous hand dish wash pastes which contain Na-LAS, calcium carbonate as abrasive and a non-ionic surfactant. The compositions do not contain Mg-LAS. The combination of Na-LAS and the additional surfactant produces ductile pastes at a constant total surfactant. The exemplified compositions are highly alkaline due to presence of significant amount of soda and silicate, a part of which gets used up in neutralization of LAS acid.

Similar compositions are also disclosed in WO14086634 A1 (Henkel). The use of Ca-LAS as a surfactant is disclosed in alkaline laundry detergent powders (US4162994 B, Lever Brothers, 1979) as well as non-aqueous scouring powders (US3772204B, Colgate-Palmolive, 1973). We have determined that cleaning compositions having Ca-LAS but no Mg-LAS are particularly prone to phase separation. This is presumably because Mg-LAS provides some stability to Ca-LAS. We could not find any published solution for the technical problem.

Therefore, compositions which contain Ca-LAS as well as Mg-LAS and which are obtained by neutralization of LAS-acid with dolomite, do not face such a problem.

Therefore, there is need for stable hard surface cleaning compositions comprising Ca- LAS as a primary surfactant, but which do not contain more than a particular amount of Mg-LAS.

Summary of the invention

It has been determined that certain non-ionic surfactants having particular featu be used to stabilize the compositions.

Therefore in accordance with the present invention there is provided an aqueous abrasive cleaning composition comprising:

Aqueous abrasive cleaning composition comprising:

(i) calcium salt of linear alkyl benzene sulphonic acid;

(ii) abrasive particles; and

(iii) alkoxylated fatty alcohol;

wherein

(a) the composition has a pH in the range of 6 to 8 at 20 °C;

(b) the composition comprises an amount of magnesium salt of linear alkyl benzene sulphonic acid that is 0 to 1 % of the amount of said calcium salt;

(c) the composition comprises less than 1 wt% sodium salt of linear alkyl benzene sulphonic acid;

(d) said abrasive has a Moh's index of 0.5 to 7;

(e) the amount of surfactant on the surface of the abrasive particles is 0 to 10 % of the total surfactant of the composition; and (f) said alkoxylated fatty alcohol has an HLB in the range of 1 1 to 20 and carbon chain length in the range of 12 to 16.

Also in accordance with the present invention there is provided a method of preparing the compositions of the present invention, said method comprising the step of preparing calcium salt of linear alkyl benzene sulphonic acid by reacting linear alkyl benzene sulphonic acid with calcium oxide and/or calcium hydroxide.

Detailed description of the invention Hard surfaces include floors, walls, tiles, windows, cupboards, sinks, showers, shower plastified curtains, wash basins, WCs, fixtures and fittings made of different materials like ceramic, vinyl, no-wax vinyl, linoleum, melamine, glass, Formica®, vitroceramic, plastified wood, metal or any painted or varnished or sealed surface. It also includes household appliances including, but not limited to refrigerators, freezers, washing machines, automatic dryers, ovens, microwave ovens and dishwashers. The term dishes includes glasses, pots, pans, baking dishes and flatware made from ceramic, china, metal, glass, plastic (polyethylene, polypropylene, polystyrene), wood, enamel, Inox®, teflon, or any other material commonly used in the making of articles used for eating and/or cooking.

Unless specified otherwise, wt% as used herein is defined as percentage by weight based on total weight of the composition.

The aqueous abrasive cleaning composition of the present invention comprises calcium salt of linear alkyl benzene sulphonic acid (abbreviated as Ca-LAS).

Usually abrasive cleaning compositions for hard surface cleaning contain sodium salt of linear alkyl benzene sulphonic acid, often abbreviated as Na-LAS. While such compositions are efficacious, they are also very strong and thereby tend to be harsh to the user's skin, e.g. hands.

The usual way of making compositions containing Na-LAS is to neutralize linear alkyl benzene sulphonic acid (LAS) with an alkali like sodium carbonate, sodium silicate or sodium hydroxide. The material which is widely used is sodium carbonate (also known as soda ash or soda). Usually a stoichiometric excess of soda is made to react with a given amount of LAS-acid to produce Na-LAS. Excess soda remains in the formulation and serves as a builder or alkaline material. Alkaline compositions provide better grease removal; however, as indicated earlier, they tend to be significantly harsh.

Ca-LAS provides a milder alternative to Na-LAS but the usual way of making

compositions containing Ca-LAS is to react LAS-acid with dolomite. The known way to make a hard surface cleaning composition containing Ca-LAS as the primary surface- active agent is to mix LAS-acid with water to prepare a slurry. Dolomite, usually stoichiometric excess, is then added to the slurry. Sufficient amount of time is allowed to ensure that the acid gets neutralized. Progress of the reaction is periodically checked by determining the pH. Dolomite is a naturally occurring mineral and the principle member of

the dolomites group of minerals. Neutralization of linear alkyl benzene sulphonic acid (LAS-acid) with dolomite results in a mixture of Ca-LAS and Mg-LAS.

However, this leads to a technical problem which has two aspects.

On the one hand there is need for milder hard surface cleaning compositions which contain Ca-LAS instead of Na-LAS. On the other hand, there is need for a non-dolomite route to neutralize LAS-acid. When dolomite is used to neutralize LAS acid, a part of sulphonic acid forms Mg-LAS, which stabilizes the formulations.

However, the absence of Mg-LAS in compositions containing Ca-LAS made by a non- dolomite route leads to unstable products. In particular, compositions devoid of Mg-LAS are especially prone to separation into solid and liquid phases and this is particularly observed in the case of samples stored at high temperatures, e.g. 40 °C, or low temperatures, e.g. 5 °C.

On the other hand, the availability of dolomite of consistent specifications is also a problem from supply chain perspective. Therefore, there is need for compositions which are made by a non-dolomite route of neutralisation but for that the problem of instability needs to be addressed. We have determined that certain non-ionic surfactants having particular features can stabilize such compositions.

The aqueous abrasive cleaning compositions in accordance with this invention comprise calcium salt of linear alkyl benzene sulphonic acid (i.e. Ca-LAS). It is preferred that compositions in accordance with the invention comprise 0.1 to 15 wt% calcium salt of linear alkyl benzene sulphonic acid, more preferably 0.5 to 10 wt% and even more preferably 1 to 5 wt%.

Magnesium salt of linear alkyl benzene sulphonic acid is in an amount not more than 1 % of the amount of said calcium salt. For example, if the total amount of Ca-LAS is 15 wt%, then the maximum amount of Mg-LAS is 0.15 wt%, which amounts to not more than 1 % of the amount of the calcium salt.

However, it is preferred that the aqueous abrasive cleaning compositions of the invention do not contain magnesium salt of linear alkyl benzene sulphonic acid.

Thus, the amount of magnesium salt of linear alkyl benzene sulphonic is from 0 to 1 % of the amount of the calcium salt. Alkoxylated fatty alcohol

Compositions in accordance with the invention comprise one or more alkoxylated fatty alcohol. These are non-ionic surfactants. The HLB of the alkoxylated fatty alcohol is in the range of 1 1 to 20 and the carbon chain length of said fatty alcohol is in the range of 12 to 16. All non-ionic surfactants have an HLB value. The higher the number, the more hydrophilic the surfactant. On the other hand, surfactants having lower HLB value are more lipophilic. Alkoxylated fatty alcohols lend stability to the compositions even in the total absence of Mg-LAS or when the Mg-LAS content is minimal. It is particularly preferred that the degree of ethoxylation in said alkoxylated fatty alcohol is from 5 to 8 moles of ethylene oxide units. Alkoxylated fatty alcohols having a degree of ethoxylation from 5 to 8 show particularly good technical effect by stabilizing the compositions which are stored at temperatures higher or lower than the normal room temperature (i.e. a temperature around 20 °C).

It is preferred that compositions in accordance with the invention comprise 0.05 to 10 wt% of alkoxylated fatty alcohol, more preferably 0.1 to 8 and even more preferably 1 to 5 wt%. A combination of one or more such non-ionic surfactants may also be used.

Preferably the ratio calcium salt linear alkyl benzene sulphonic acid to alkoxylated fatty alcohols is 1 :1 to 2:1.

The abrasive

The compositions in accordance with the invention comprise an abrasive having a Moh's Index of 0.5 to 7.

It is preferred that compositions comprise 1 to 50 wt% abrasive, preferably 5 to 40 wt% and more preferably 10 to 30 wt%. The abrasive preferably is at least one of bentonite, china clay, calcite, dolomite or feldspar but any other suitable abrasive or abrasives may be used. It is preferred that the abrasive comprises at least calcite and preferably in an amount of at least 50 wt% of the total amount of abrasives in the composition.

It is preferred that the average particle size of abrasive is 0.5 to 400 μηη, more preferably 10 to 200 μηι.

Viscosity

Most hard surface cleaning compositions like dish wash composition and kitchen cleaners need a certain viscosity inter alia for ease of application and spreadability. Therefore it is preferred that the compositions in accordance with the invention have a viscosity of 500 to 2000 cP at 20 °C. The viscosity may be measured by any suitable method. It is preferably measured at 20 °C at a shear rate from 1 s ^"1 to 50 s ^"1 , using a Haake ^® AR1000 Rheometer with cone and plate assembly.

It will be understood that any known method can be used to build the required viscosity, including for example by using the abrasive particles present in the composition.

As an alternative to the abrasive, or in addition to the abrasive, the compositions in accordance with this invention preferably comprise a polymer. The purpose of the polymer is to provide some viscosity to the compositions. It is preferred that the polymer is a water-swellable polymer or an associative polymer. It is preferred that the polymer provides the desired viscosity when the pH of the compositions is in the range of 6 to 8. Whenever the polymer is present, it is preferred that the amount thereof is 0.005 to 10 wt%. It is preferred that the polymer is one or more of polyacrylic acid, polyacrylates, cross-linked acrylates, guar gum or its derivatives, starch-acrylic grafted copolymers, hydrolysate of starch-acrylonitrile grafted copolymers, crosslinked polyoxyethylene, cross-linked methyl cellulose, sodium carboxymethylcellulose or partially cross-linked water-swellable polymers of polyethylene oxides and polyacrylamide or

isobutylene/maleic acid copolymer. Whenever present, it is preferred that the compositions in accordance with the invention comprise 0.008 wt% to 5 wt% polymer, more preferably 0.01wt% to 2.5 wt% of the polymer. A particularly preferred polymer is Acusol® 880/882.

Amount of water and the pH

Compositions in accordance with the invention are aqueous, i.e. water-based. It is preferred that the compositions comprise 20 to 80 wt% water and more preferably 30 to 75 wt%, even more preferably 40 to 70 wt% and still even more preferably 50 to 60 wt%. The pH of the compositions in accordance with the invention is in the range of 6 to 8 at 20 °C. The compositions in accordance with this invention comprise less than 1 wt% of strong alkalis which include sodium hydroxide, sodium silicate and sodium carbonate. If the pH of the composition is more than 8, it is likely to adversely affect stability of the product. Similarly, at pH less than 6, there could be protonation of the nonionic surfactants, which eventually could result in unstable compositions.

The compositions in accordance with this invention may contain other ingredients which are disclosed hereinafter.

Other surfactants

Compositions in accordance with this invention may contain other surfactants.

However, they comprise less than 1 wt% sodium salt of linear alkyl benzene sulphonic acid (Na-LAS). Any excess amount of Na-LAS could tend to destabilise the compositions due to exchange of calcium ions with the sodium ions. Further, the compositions may also become more alkaline and thereby less milder.

The cleaning composition may further comprise other anionic surfactants, amphoteric and zwitterionic surfactants, provided they do not interfere with the performance or stability of the compositions. It is preferred that the amount of such other surfactants is from 0.1 to 20 wt %.

Preferably the compositions in accordance with the invention comprise less than 1 wt% cationic surfactant.

It is further preferred that in the compositions according to the invention, the total amount of surfactants is not greater than 40 wt%. In other words, the Active Detergent (AD) level is not greater than 40 %. The term total surfactant means the sum total of all surfactants contained in the compositions, which includes calcium salt of linear alkyl benzene sulphonic acid. Preferably the AD level is not more than 30 wt%, with a preferred level being not more than 20 wt%, and even more preferred not more than 10 wt%. Suitable amphoteric surfactants are derivatives of aliphatic secondary and tertiary amines containing an alkyl group of 8 to 20 carbon atoms and an aliphatic group substituted by an anionic water-solubilising group, for instance sodium 3- dodecylamino-propionate, sodium 3- dodecylaminopropane-sulphonate and sodium N 2-hydroxy-dodecyl-N-methyltaurate.

Examples of suitable zwitterionic surfactants include derivatives of aliphatic quaternary ammonium, sulphonium and phosphonium compounds having an aliphatic group of from 8 to 18 carbon atoms and an aliphatic group substituted by an anionic water- solubilising group, for instance betaine and betaine derivatives such as alkyl betaine, in particular C12-C16 alkyl betaine, 3-(N,N-dimethyl-N-hexadecylammonium)-propane 1 - sulphonate betaine, 3- (dodecylmethyl-sulphonium)-propane 1 -sulphonate betaine, 3- (cetylmethyl-phosphonium)- propane-1 -sulphonate betaine and N,N-dimethyl-N- dodecyl-glycine. Other well known betaines are the alkylamidopropyl betaines e.g. those wherein the alkylamido group is derived from coconut oil fatty acids.

Further examples of suitable surfactants can be found in the well-known textbooks: 'Surface Active Agents' Vol.1 , by Schwartz & Perry, Interscience 1949; 'Surface Active Agents' Vol.2 by Schwartz, Perry & Berch, Interscience 1958; the current edition of 'McCutcheon's Emulsifiers and Detergents' published by Manufacturing Confectioners Company; Tenside-Taschenbuch', H. Stache, 2nd Edn., Carl Hauser Verlag, 1981.

Other ingredients

Compositions according to this invention may include additional ingredients to improve or enhance the in-use performance.

Such ingredients include colour, fragrance, soil suspending agents, detersive enzymes, compatible bleaching agents, freeze-thaw stabilisers, bactericides, preservatives, hydrotropes and perfumes.

Product Form

It is preferred that the aqueous hard surface cleaning compositions according to the invention are liquids or creams or pastes, which may be directly applied to the hard surface. An example of a commercial cream is CIF ^® from Unilever. Packaging

The aqueous hard surface cleaning composition according to the invention can be packaged in any suitable container. Preferably, the composition is packaged in a plastic bottle with a detachable closure /pouring spout. The bottle may be rigid or deformable. A deformable bottle allows the bottle to be squeezed for dispensing. If clear bottles are used, they may be made of PET or Polyethylene. The bottle may be provided with one or more labels, or with a shrink-wrap sleeve, which is desirably at least partially transparent, for example 50% of the area of the sleeve is transparent. The adhesive used for any transparent label should preferably not adversely affect the transparency. The compositions can also be packed in other formats like sachets and pouches.

Method of preparing Methods to prepare Ca-LAS containing cleaning compositions include the step of neutralizing acid-LAS with Dolomite or e.g. calcite. This way any deliberate excess of the neutralizing agent (i.e. Dolomite or calcite) will act as the abrasive in the final composition. We have found that these methods may not always result in a composition comprising abrasive particles with the required cleaning properties, as the surface of the remaining abrasive particles will be covered with a substantial amount of the total surfactant present in the composition. In some cases this could be as much as more than 10, 20 or even 30 % of the total amount of surfactant in the composition.

In the compositions of the present invention, the amount of surfactant on the surface of the abrasive particles is from 0 to 10 % of the total surfactant of the composition.

Preferably 0.1 to 8, more preferably 0.5 to 6 and even more preferably 1 to 4 %.

The amount of surfactant present on the surface of the abrasive particles is determined according to the method described in the Examples below.

As such the present invention further provides a method of preparing a composition of the present invention comprising the step of preparing the calcium salt of linear alkyl benzene sulphonic acid by reacting linear alkyl benzene sulphonic acid with calcium oxide and/or calcium hydroxide. Preferably said step takes place in the absence of the abrasive particles present in the final composition.

The invention will now be further described with reference to the following non-limiting examples. Examples

Determination of surfactant deposited on the particles

The cleaning composition comprising the abrasive particles and Ca-LAS is centrifuged twice at 7500 rpm for 20 min. The particles are removed from the supernatant and washed thoroughly with Dl water to ensure removal of all soluble ingredients deposited on the particle. The washed particles are then dried in a hot air oven. To remove the calcium salt of linear alkyl benzene sulfonate from the surface of the particles, the dried particles are washed with methyl alcohol. The stock solution comprising methyl alcohol and leached calcium salt of linear alkyl benzene sulfonate is titrated against 0.4 mM hyamine solution in presence of chloroform and mixed indicator. Based on the volume of hyamine solution required for the titration, the amount of surfactant present in the stock solution is determined. Based on this, the amount of surfactant deposited on the particle surface is calculated. The % of surfactant deposited on the particle is then calculated using the formula below:

% surfactant deposited on the particle surface = (amount of surfactant deposited on the particle surface/total amount of surfactant present in the composition) ^* ! 00

Example 1 : Preparation of aqueous hard surface cleaning cream composition devoid of magnesium salt of linear alkyl benzene sulphonic acid to show alkoxylated fatty alcohol requirements:

Step 1 :

A plastic beaker of suitable size was positioned in alignment with an overhead stirrer. In another beaker, 550 g of demineralized water was heated to 65 to 75 ^° C. About half the quantity of water was then added to the first mentioned beaker and it was stirred at about 150 rpm. This was followed by addition of 5 g coco fatty acids and 0.2 g silicone oil to suppress the foam. Thereafter, 200 g calcite was added to it to form a mix, which was stirred for about five minutes. Thereafter, 33 g of commercial linear alkyl benzene sulphonic acid (LAS-acid) was added slowly. A nonionic surfactant was then added and the mix was stirred for few minutes.

Step 2:

Thereafter, the balance amount of water, (275 g) and 200 g calcite was added to the beaker and the contents were stirred for five more minutes. In the composition 4 (of table 1 ), 50 g bentonite clay was also added to get the right viscosity.

A compositions containing a polymer (in addition to calcite) were also prepared. In this case, the procedure (step 2) was as follows:

In another plastic container, the balance amount of water 450 g was added. To this 0.3 g of polymer was added and stirred for 5 minutes at 150 rpm. To this, the premix was added and stirred for five minutes. This was followed by addition of 350 g of calcite and the contents were stirred for twenty minutes.

The final formulations of all the compositions is summarized in table 1.

Table 1

Note:

• Span® 80 is Sorbitan monooleate, a type of non-ionic surfactant from Croda.

HLB value of this surfactant is 4.3 ± 1. Its carbon chain length is 24 to 26

• PEG-200 is polyethylene glycol of molecular weight 200 Daltons coupled with oleic acid. Polyethylene glycol mono-oleate is also a non-ionic surfactant and its HLB value is 8 to 9.3.

• Acconon® MC8-2 Ex. Abitec, is a non-ionic surfactant which is Polyoxyethylene (8) Caprylic/Capric Glycerides. Its HLB value is 13 to 15 and it has carbon chain length of 8 to 10.

• Lialet® 125-5 Ex. Sasol is fatty alcohol polyethylene glycol ether (alkoxylated fatty alcohol) based on LIAL® 125 and ethylene oxide (5 moles). Its HLB value is about 1 1 and its carbon chain length is 12 to 16.

· Lialet® 123-8 Ex. Sasol is fatty alcohol polyethylene glycol ether (alkoxylated fatty alcohol) based on LIAL® 123 and ethylene oxide (8 moles). Its HLB value is about 12 and its carbon chain length is 12 to 16. All the compositions of table 1 were subjected to stability studies. Samples of each composition were stored at 5 °C, 28 °C and 40 °C for 30 days. Observations recorded after 30 days are summarized in table 2.

Table 2

Note:

(1 ) Yes/No refers to phase separation. "Yes" implies that there was phase

separation.

(2) Where phase separation was observed, the compositions separated into an aqueous phase and solid phase. It was not possible to measure viscosity.

The data in table 2 when read-with the formulations of table 1 , clearly indicates that compositions not containing alkoxylated fatty acid having a certain HLB and carbon chain length (X, Y and Z) are unstable under all conditions.

In particular, the data pertaining to composition Z indicates that alkoxylated fatty alcohols having HLB of 1 1 to 20 do not provide desired results. Comparison of the data for composition Z and composition 1 indicates that it is a combination of the right chain length and the right HLB which provides technical effect.

The right balance of HLB (1 1 to 20) and carbon chain length (C12 to C16) provides optimal stability (Compositions 1 , 2, 3, 4 and 5).

Example 2: Preparation of aqueous hard surface cleaninq cream composition devoid of magnesium salt of linear alkyl benzene sulphonic acid and comprising abrasive particles having an amount of surfactant on the surface thereof of 0 to 10% of the total amount of surfactant: Table 3

Preparation of compositions outside the invention (A-l and A-ll)

40% of the total water of the composition mentioned in Table above was heated to 50°C and added in a beaker. To that Silicone DB 310 and coconut fatty acid (if required) were added. An overhead stirrer equipped with an anchor blade was used to stir the mixture at 105 rpm. To this mixture, a part of the calcite was added and stirred for 2 min. LAS acid was then added and mixed for 10 min. To this, the remaining water, Nl 7 EO and Acusol 882 were added and stirred. Then the remaining Calcite was added to the mixture and kept for stirring for about 25 min. The composition was decanted and stored in an appropriate container.

Preparation of compositions as per the scope of the invention (B-l and B-ll)

Half of the total amount of water at 50°C, Silicone DB 310 and Calcium hydroxide were added in a beaker and stirred for 10 min using an overheard stirrer. LAS acid was then added and mixed for 10 min. The remaining water (at 25°C) was then added to the beaker along with calcite and stirred for 5 min. Then Nl 7 EO, coconut fatty acid (if required) were added to the mixture and stirred for 5 min (if required). Acusol 882 was added and stirred for 15 min. The composition was decanted and stored in an appropriate container. The amount of surfactant present on the surface of the abrasive particles was determined for A-l and B-l using the method described above. The results can be found in Table 4.

Table 4

To determine the cleaning performance a model bathroom soil composition containing calcium stearate was sprayed on enamel tiles for uniform deposition and then baked at a certain temperature for a fixed amount of time.

5g of the composition was spread on the model bathroom soil uniformly. A pressure of 340 g/cm2 was applied on the soil through a head, covered with a cloth as an implement. The soiled plate was then scrubbed in a cleaning equipment for fixed rotations. After cleaning, the tile was rinsed under running water. The tile was weighed after drying and the % soil removal was calculated gravimetrically. The results can be found in Table 5.

Table 5

Example Bathroom soil removal (%)

A-l 23

B-l 30

A-l I 35

B-l I 43