Colorfastness and pH Testing Before Cleaning

Purpose

A dye that runs cannot be put back. Colorfastness testing is the last cheap moment in the visit: it costs a few minutes and one white towel, and the alternative is a bled border on a wool rug or a pink halo across a bedroom that the shop pays to replace. The second half of the job is the pH of what actually leaves your sprayer, which is not the pH on the jug and not the pH of the concentrate. Both get measured and recorded before the first pre-spray goes down.

The rule: the test is run with the product you will use, at the dilution you will use, at the temperature and agitation you will use, on every distinct color in every distinct area.

Scope

Covers pre-cleaning dye-bleed testing and working-solution pH verification on wall-to-wall carpet, stair runners, and rugs cleaned in place, for every product that will contact the fiber including pre-spray, spotter and rinse.

Does not cover fiber identification or the working-limits card, which is the pre-inspection SOP and is the input to this one. Does not cover dye-loss repair or re-dyeing, and does not cover in-plant rug immersion, where bleed control is a submersion and drying problem with its own SOP.

Roles and responsibilities

Procedure

1. Mix the working solution the way production will mix it. Label dilution, the water you will actually use, and the temperature the process runs at. Acceptance: the mix ratio, the product name and the water temperature are written down before any test runs. Wrong looks like testing a hand-mixed cup and running a metered inline dilution that is twice as strong; if you cannot reproduce the production dilution in a test cup, test at the sprayer outlet instead. Hazard: concentrates are the dangerous form of every product on the truck, so wear splash goggles and chemical gloves while pouring, add concentrate to water rather than water to concentrate, and never combine an acid-side rinse or spotter with any chlorinated product, which liberates chlorine gas. If concentrate reaches an eye, flush at the nearest running water for 15 minutes and get medical attention; do not finish the job first.

2. Measure the pH of the mixed solution and check it against the limits card. Strips read in half-unit steps, so record to the nearest 0.5; where a finer number is needed, use a meter calibrated that morning against fresh buffers and record to 0.1. Acceptance: the reading falls inside the band on the fiber limits card, which for wool this shop holds at 5.5 to 7.5. Wrong looks like a general-purpose pre-spray at 9.5 going onto wool because the jug said "carpet"; if the reading is outside the band, that product is out, choose one whose label states a fiber-safe range and re-measure. Hazard: dipping strips means an open container of working solution at hand height, so keep it off the customer's furniture, cap the concentrate before you test, and do not aerosolize the solution to speed a reading.

3. Pick the test locations, one per distinct color per area. A bordered carpet is at least two tests. A multi-color berber is one per color present in the pattern. Every separate room is its own set, because a builder often used two dye lots. Acceptance: a written count of colors tested per area that matches the colors actually present. Wrong looks like one test in a hallway standing in for a whole house; if a color exists that you did not test, it is untested, and untested means it does not get cleaned until it is. Hazard: test points sit at edges and under furniture where tack strip and staples are, so probe with a tool rather than fingertips and keep hands out of the gripper channel.

4. Run the wet test. Apply the working solution to a small area at the test point, let it dwell for the label dwell time, then press a folded white terry towel into it with firm hand pressure for about ten seconds. Read the towel in daylight, not under a lamp. Acceptance: no visible color on the towel. Wrong looks like a faint pink or blue shadow, which is a fail and not a pass; any visible transfer at all sends you to step 7 rather than into production. Hazard: pressing a solution-wet towel with a bare hand is direct skin contact with an alkaline or solvent product for the full ten seconds, so this is done gloved, and any product that reaches skin gets rinsed at once rather than wiped on a shop towel.

5. Repeat the test with heat and agitation if production will use them. Dye that holds at rest will move under a brush or a heated bonnet, and the bonnet is where most in-place bleed events start. Acceptance: no transfer onto the towel after the same agitation the job will use, at the same solution temperature. Wrong looks like a clean rest test followed by a pink bonnet on the third pass; if transfer appears only under agitation, agitation comes off the method for that area, not just the product. Hazard: heated solution at the wand is hot enough to scald through a wet glove, so set the test cup down before agitating rather than holding it, and keep the heated line off the customer's floor covering and out of the walking path.

6. Test the neighbors the water will reach. Wet a cotton swab and touch any binding, serged edge, wall base, wood transition or upholstery skirt within a wand's width of the work. Acceptance: no dye on the swab from any adjacent material, and no swelling or blanching on a wood transition after two minutes. Wrong looks like an unbled carpet with a bled binding, which is the same callback; where the binding moves color, mask it with a moisture barrier and clean no closer than the mask, and where a wood transition reacts, dry-strip that band by hand. Hazard: swab testing puts you face-down at floor level beside the vacuum path, so kill the wand and the machine before you get down, because a hose dragged across a kneeling tech is how wrists get broken.

7. Choose the response from what the test showed, and write it down. No transfer at rest or under agitation is a clear proceed at the tested product. Faint transfer at rest only means dropping dwell to the label minimum, moving to an acid-side rinse, and working drier with the fastest possible extraction and immediate air movement. Visible transfer under agitation means no agitation and low moisture, or no cleaning of that color at all. Acceptance: one of those three responses selected in writing, with the product and dilution named. Wrong looks like "it was only a little" followed by a full-wet pass; a bleeder is cleaned at reduced risk only with the owner's written approval on the ticket, never on a tech's judgment alone. Hazard: none at this step, it is a decision made standing still, though make it before the operator has mixed the production batch, not after.

8. Dry the test points, verify them, and close the record. Extract each test point dry, place air movement on it, and re-check it after the surrounding carpet is dry. Acceptance: no ring, no lightened patch and no stiffness at any test point, and every mask or barrier placed at step 6 removed before you leave. Wrong looks like the customer finding eight faint circles the next morning; if a test point rings, wick-treat it before departure rather than promising to come back. Hazard: air movers put cords across the room at the end of the visit when the customer starts moving again, so run them along the wall line, and tell the occupants which room has a machine in it before you leave it running.

The record this produces

Product name, dilution ratio and water temperature; the measured working-solution pH with the instrument used and its resolution; the count of colors tested per area and where each test point sits; wet-test result and agitation-test result per point; adjacent-material swab results; the chosen response; and the customer signature on any area declined. Photograph the towel, dye and all, because a photographed towel is what makes the decline conversation short six months later when the customer remembers it differently.

The office files this against the address. A house that bled once bleeds again, and the next crew needs the product that passed, not the product that was tried.

Worked pass: bordered wool-blend rug cleaned in place

Living room, wool-blend cut pile with a saturated red border about 18 in wide on all four sides. The limits card from pre-inspection reads wool, band 5.5 to 7.5, reduced heat, groomer agitation only.

Step 1 mixes the shop's general pre-spray at the label ratio in a test cup at the same temperature the inline will deliver. Step 2 fails immediately: strips read 9.5, and 9.5 is outside the 5.5 to 7.5 band on the card. Stop rule fires, the product is out. A wool-rated pre-spray is mixed instead and reads 7.0 on strips, inside the band with 0.5 to spare against the top of it.

Step 3 counts two colors: the field and the red border, so two test sets, four points total, one field and one border on each of two sides.

Step 4 runs the wet test at the label dwell. Both field points read clean. Both border points put a distinct pink shadow on the white towel. That is a fail at rest, not a marginal result.

Step 5 does not run on the border, because a color that moves at rest is not put under agitation. It does run on the field, with the groomer and at the reduced solution temperature, and the field stays clean.

Step 6 swabs the serged edge and the oak transition at the doorway. The serged edge is clean. The oak shows no swelling after two minutes.

Step 7 selects two different responses in one room, which is the point of testing per color: the field gets a normal pass with the wool-rated pre-spray at pH 7.0, groomer only, reduced heat. The 18 in border across all four sides is declined for wet cleaning entirely and gets dry soil removal only. The owner is called, agrees, and the decline goes on the ticket with the customer's signature.

Step 8 extracts and dries the four test points, and all four are re-checked after the field dries. No ring on any of the four.

Self-check against the sections above: the pH used in production, 7.0, is the pH measured at step 2 and sits inside the 5.5 to 7.5 band the pre-inspection card set; no product entered this run that had not been measured; and the two colors counted at step 3 are the same two colors carried through steps 4, 5 and 7.

References

• IICRC S100 Standard for Professional Cleaning of Textile Floor Coverings, in the edition your certifying body currently publishes, which reaches you through your certification rather than by law
• The product label and safety data sheet for every product on the truck, at the dilution stated on the label; label directions are legally binding in the chemical trades, and the SDS is the source for incompatibility, including acid and chlorine
• The carpet or rug manufacturer's care sheet, which governs where it disagrees with a general standard
• See related: carpetcleaning-pre-inspection-and-fiber-identification, carpetcleaning-dye-stain-removal, carpetcleaning-pre-spray-chemistry