Chemical Mixing and Dilution Standard

Purpose

The mixing station is where a carpet cleaning shop's chemical risk concentrates. At the wand everything is already diluted; at the tailgate a tech handles neat alkaline booster, neat solvent, and a rust remover that may be fluoride-based, usually in the open with a customer's kids somewhere behind them. It is also where results are decided: an under-dosed prespray causes most "it did not come clean" callbacks, and an over-dosed one causes most sticky, fast-resoiling ones.

This standard fixes what gets read before mixing, what gets worn for the route the product actually has, the order liquids go together, what may never share a container, and what gets written on the jug. It ends with a verification a tech can do in 30 seconds that catches a wrong-jug mistake before it reaches a wool rug.

Scope

Covers measuring and mixing carpet cleaning concentrates on the van or at the shop: presprays, rinse agents, defoamers, spotters, deodorizers, protectors, rust removers and EPA-registered disinfectants.

Does not cover: which product to select for a soil or fiber (the pre-spray chemistry and fiber references); dwell time by soil class (its own reference); application at the wand or sprayer (the service SOPs); and disposal of waste solution (the waste water SOP, which step 10 hands off to).

Roles and responsibilities

Procedure

1. Read the label for the product in your hand, not the one you used last month. Confirm the dilution direction, the required PPE and any use restriction, and pull the SDS if you have not read it. Accept: the label's dilution direction quoted onto the ticket in its own units, plus the PPE it names. Wrong: mixing from memory after a supplier reformulates. Stop rule: an unreadable or missing label makes the container unusable - back to the shop for identification, not into a tank. Hazard: for an EPA-registered disinfectant the label is legally binding, and use inconsistent with its labeling violates FIFRA at 7 U.S.C. 136j(a)(2)(G), so label directions govern over anything here.

2. Mix in open air, upwind, away from the door the household uses. Van doors open, not inside a closed box, a bathroom or a utility closet. Accept: mixing outdoors or at an open tailgate with air moving past you, children and pets not within reach. Wrong: mixing in the van box with the doors pulled to because it is raining. Stop rule: nowhere with air movement means you mix at the shop and carry ready-to-use solution. Hazard: vapor from a solvent booster or an acid rust remover builds in a closed van box faster than anyone expects, and the first symptom is a headache you blame on the day.

3. Wear what the label and SDS name for the route that product actually has. Eye protection every time; the glove the SDS names, not whatever is on the seat. Accept: eye protection on, the specified glove type on, a respirator worn only under a written program per 29 CFR 1910.134. Wrong: thin nitrile exam gloves for a fluoride-based rust remover - hydrofluoric acid and ammonium bifluoride penetrate skin with little immediate pain and cause deep, delayed injury. Stop rule: if the label requires a respirator and nobody on site is in a 1910.134 program, the crew does not do the work that required one. Hazard: for a fluoride product, know the response before opening it: flush at once, apply the calcium gluconate gel the SDS specifies if the shop stocks it, and get medical care immediately while telling them it was hydrofluoric acid.

4. One product per container, and never combine chemistries. Rinse a container between products, and keep acid spotters away from anything chlorinated or ammoniated. Accept: each container holding one product, rinsed and dried before a different product enters it. Wrong: topping up a spotter bottle that still holds a different chemistry. Stop rule: any sharp or choking odor stops mixing - move upwind, leave the area open, and do not lean in to identify it, because smell is not a test and both chlorine and chloramine deaden the sense at injurious levels. Hazard: acid plus a chlorinated product releases chlorine gas, ammonia plus a chlorinated product releases chloramine, and both injure the lung.

5. Water in the container first, then the concentrate. Measure the water volume before anything else goes in. Accept: the container holding its full measured water charge before concentrate is poured. Wrong: a splash of concentrate in the bottom followed by a hose, which is how a concentrated splash reaches a face. Stop rule: concentrate already in an empty container gets filled slowly with the container on the ground and your face away, rather than adding more concentrate to fix the ratio. Hazard: strong acids and alkalis release heat as they dilute, so concentrate goes into water and never the reverse, at the water temperature the label states.

6. Measure with a graduated cup and know which dilution convention the label uses. A label may direct ounces per gallon or a parts ratio, and the two are not identical. Accept: a measured volume from a graduated cup, the convention written on the ticket, and the label's per-gallon direction governing when both appear. Wrong: dosing by cap-fuls or a count of glugs. Stop rule: an ambiguous label direction is a call to the shop manager, not a guess on the high side. Hazard: none beyond splash, which step 3's eye protection covers; keep the cup dedicated to one product family so residues do not meet in it.

7. Scoop powders low and slow, into water that is already in the container. Alkaline boosters and oxygen powders are the inhalation route this trade forgets. Accept: no visible dust cloud at the container mouth while charging. Wrong: pouring powder from shoulder height into a bucket, which lofts fine alkaline dust into the breathing zone. Stop rule: visible dust means stop, let it settle, and change technique rather than holding your breath through it. Hazard: that dust burns eyes and irritates airway, and step 3's respirator gate applies to it, so a product whose SDS calls for respiratory protection is not mixed in the field without a program.

8. Label the secondary container before it leaves your hand. Product identity, the hazard words, the dilution and the date mixed. Accept: all four written on the container, legible after a wet shift. Wrong: an unlabeled jug of clear liquid on a van shelf, which causes the failure in the worked pass below. Stop rule: an unlabeled container of unknown contents is emptied to the waste tank under the waste water SOP, not sniffed and not used. Hazard: OSHA requires workplace labeling on secondary containers at 29 CFR 1910.1200(f)(6), and the SDS access duty at 1910.1200(g) is what makes step 1 possible.

9. Verify the batch before it reaches fiber. Check the finished solution with a pH strip and compare it to the band for the fiber you are about to clean. Accept: the reading inside the label's stated band for that product and fiber; for wool and other protein fibers the accepted working band is mildly acidic to neutral, commonly given as roughly 4.5 to 8.5 in IICRC S100 in the edition your shop holds, and the product label governs. Wrong: a reading well outside the band, which means the wrong concentrate, the wrong dose or a contaminated container. Stop rule: out of band means the batch is dumped and remixed, never diluted further to drag the number down. Hazard: dip the strip from a poured sample rather than reaching a hand into the container.

10. Secure, close and account for everything before the van moves. Cap and return the concentrate to its place, rinse the measuring cup, strap the jugs upright, and route leftovers. Accept: every concentrate container closed and upright in its restraint, cups rinsed, spill kit complete, leftover mixed solution emptied into the waste tank under the waste water SOP. Wrong: a loose gallon of alkaline concentrate rolling in a van box, which becomes a spill at the first hard stop. Stop rule: a container you cannot close and restrain does not travel. Hazard: never tip a leftover batch onto ground or into a storm drain, and a spilled concentrate gets contained with the kit's absorbent, kept out of any drain, and reported to the shop manager before cleanup.

The record this produces

The ticket carries: product name, the label dilution direction as written, the convention used, the measured concentrate and water volumes, the batch size, the pH reading with the fiber it was mixed for, PPE worn, and the disposition of any leftover.

The pH reading earns the section. It is the only entry that can prove, later, that the solution which touched a wool rug was in band, and it is what catches the wrong-jug error while the rug is still dry. The shop manager reads the dilution field across techs: two people mixing the same product at meaningfully different rates is a training gap that shows up as inconsistent results long before anyone connects the two.

Worked pass, with a step that failed

Mixing a wool-safe prespray for a hand-cleaned wool area rug. Batch size 5 gallons.

Step 1: the label directs 4 fl oz per gallon of water. The tech noted the convention on the ticket, because the same product's literature also describes it as roughly one to thirty-two: at 128 fl oz per gallon, 5 gallons of finished solution is 640 fl oz, and one part in thirty-three total parts would be 640 divided by 33, or 19.4 fl oz, against 20.0 fl oz from the per-gallon direction. The difference of 0.6 fl oz on 19.4 is about 3 percent, immaterial here, and the per-gallon direction on the label governs, so 20.0 fl oz was the target.

Steps 2 through 7 ran clean: mixed at an open tailgate upwind of the front door, goggles and the SDS-specified glove on, 5 gallons of water in the container first, then 20.0 fl oz measured in a graduated cup from a 1 gallon jug on the van shelf.

Step 9 failed. The strip read 10.5. The acceptance for wool is the label's band inside roughly 4.5 to 8.5, and 10.5 is well above it.

The stop rule ran as written: no attempt to correct the batch by adding water or acid rinse. Working back, the 1 gallon jug had no secondary container label, which is a step 8 failure from the previous week - it had been decanted with general alkaline prespray, not the wool-safe concentrate. The 5 gallon batch went into the waste tank for sanitary disposal. The jug was labeled with its actual contents and set aside for synthetic work, a fresh 20.0 fl oz was measured from the correctly labeled wool-safe concentrate into a new 5 gallons of water, and the re-check read 7.5, inside the band.

Total delay was about 15 minutes. Carried through to the rug, that batch would have put an alkaline solution on wool, risking dye bleed and permanent fiber damage on an item the customer values more than the whole invoice, and it would have been found by the customer rather than by a strip.

References

• See related: Waste Water Disposal and Fresh Water Fill SOP - owns the sanitary route step 8 and step 10 send batches to.
• See related: Pre-Spray Chemistry and Pre-Spray Dwell Time by Soil Class references (which product and how long) and the Encapsulation and Low Moisture Service SOP, whose coverage gate depends on this mix being right.
• 29 CFR 1910.1200(f)(6) for secondary container labeling and 1910.1200(g) for safety data sheet access; 29 CFR 1910.134 for the written respiratory protection program any label-required respirator depends on.
• FIFRA at 7 U.S.C. 136j(a)(2)(G) for the binding force of an EPA-registered product's label directions.
• IICRC S100 Standard for Professional Cleaning of Textile Floor Coverings, in the edition your shop holds, for the wool pH guidance in step 9.