For effective cleaning with an alkaline rinse, you must first understand the type of rinse that you are using.
These formulas are divided by level of pH: neutral (7 to 8), moderate (9 to 10), and high (>11).
The key ingredient in alkaline rinses is phosphate. STPP is the primary phosphate used in powders and TKPP is the primary phosphate used in liquids. Both of these phosphates have a moderate pH of 9 to 10. Products in this pH range will have the highest amount of phosphate, which is the most effective ingredient available to prevent the re-deposition of soils and has the ability to carry the most soils away in the water stream of the rinse. A neutral pH rinse enables its use on natural fibers. A high pH rinse adds a second level of cleaning for fibers in need of restorative cleaning. The moderate pH rinse is the primary alkaline rinse used by professional cleaners.
The second step of using an alkaline rinse requires you to determine the quality of water that you will use. If treated water (reverse osmosis, deionized, or softened) is not used, then the phosphate in the rinse will immediately soften hard water in the solution hoses before being sprayed out of the wand jets. In lab testing, we determined that at a 1 to 640 dilution in hard water of 15 grains that 80% of the phosphate was used up softening the water. This means that only 20% of the phosphate was available to perform its designed cleaning functions.
Third: note that high heat is especially useful in breaking down any remaining oils not already broken down by the pre-spray. The high pH rinses designed for restorative cleaning and oil-bonded polyester fibers benefit the most from high heat. It is important to remember that high heat with hard water causes the minerals to leave the water stream bonding more readily to metal parts of the truckmount system like jets and it quickly connects.
Alkaline rinses contain more than just phosphates. Sodium metasilicate and sodium carbonate will be a higher percentage of the alkalinity found in high pH rinses while sodium bi-carbonate and acidic phosphate will be a higher percentage of the alkalinity in neutral rinses.
Corrosion inhibitors may be added beyond sodium metasilicate which serves as the inhibitor of choice for alkaline rinses.
Surfactants will usually be used to help the rinse penetrate deeper and faster into the carpet before the almost immediate extraction.
Some ingredients are not used because the level of dilution makes them ineffective in rinses such as solvents and hydrogen peroxide. Some polymers are used to neutralize the propensity of some ingredients to attract soil. However, the high dilution prevents any possibility that the use of the rinse will provide any stain resistance after its use.
In short, alkaline rinses are most beneficial when additional cleaning may be necessary. For fibers that do not need to be neutralized, you may primarily use an alkaline rinse.
Bridgepoint Systems, Extraction Rinse, Flex Fire, 6 lbs.