Unit dose capsule

A method of producing a unit dose capsule for treatment of a substrate, the method comprising steps:

• a. placing a first sheet of water-soluble polyvinyl alcohol film over a mould having sets of cavities, each set comprising three cavities;
• a first compartment, a second compartment, and a third compartment, the three cavities arranged on a sealing plane one after the other in circumferential direction;
• b. heating and applying vacuum to the film to mould the film into the cavities and hold it in place to form three recesses in the film;
• a first recess, a second recess, and a third recess, the three recesses being connected to respective side recesses by the film;
• c. filling three different parts of a substrate treatment composition into the three recesses, the three parts together forming a full substrate treatment composition, wherein the first recess accommodates the largest volume of substrate treatment composition and is filled with a first part of the substrate treatment composition and 13 to 28% gas, the second recess accommodates the smallest volume of substrate treatment composition and is filled with a second part of the substrate treatment composition and 13 to 28% gas, and the third recess accommodates substrate treatment composition more than the second compartment and less than the first compartment and is filled with a third part of the substrate treatment composition and 13 to 28% gas;
• d. sealing a second sheet of film to the first sheet of film across the formed recesses to form the sealing web comprising a peripheral sealing skirt and inter-compartment sealing webs having average sealing width in the range of 0.3 to 3 mm between compartments and a central sealing web thereby separating the compartments from one another to produce a three compartment capsule;
• and
• e. cutting between the capsules so that a series of three compartment capsules are formed, each capsule containing a part of a substrate treatment composition in three compartments.