Spray Rating Decay & Heat Reactivation

The formula

This is the expression the tool evaluates. Every term is named underneath, with the unit it must be supplied in.

How the result is derived

Step by step, from the values you type to the figure on screen.

1. The 6 inputs are read from the form on every keystroke: Initial Spray Rating, Rating After Test Washes, Test Washes, Washes Claimed, Target Rating and Gain from Pressing.
2. Each value is checked against the accepted range in the input table below. A value outside its range stops the calculation rather than producing a misleading figure — the results blank out and a message appears.
3. The validated values are substituted into the expression above, which resolves Rating at the Claimed Wash Count together with every supporting figure in one pass — no value is carried over from a previous entry.
4. The supporting outputs — Rating Lost per Wash, Reported Rating, Unpressed, Rating After Pressing, Reported Rating, Pressed, Margin, Unpressed, Margin, Pressed, Washes to Target, Unpressed, Washes to Target, Pressed, Washes Gained by Pressing and Margin When New — come from the same pass, so they always describe the same case as the headline figure.
5. Results are rounded for display only. The full-precision value is used throughout the chain, so reading a rounded intermediate figure back into the tool by hand can shift the last digit.

What each input means

Where to read each value on the floor, the unit it must be in, and the range the tool accepts.

What the tool returns

The headline figure and every supporting value it is built from.

Worked example

The tool loads with this case already solved — the Rating at the Claimed Wash Count shown above is its answer. Change one value and the difference from this baseline is the sensitivity of the result to that variable.

How to use it

1. Work through the input groups in order — Measured Decay and Claim. The defaults are a realistic case, so you can change one value at a time and watch what moves.
2. There is no calculate button. Every figure recalculates as you type or drag, which is what makes this usable for a what-if sweep rather than a single answer.
3. Read Rating at the Claimed Wash Count in the dark results panel — that is the headline figure, expressed in AATCC.
4. Check the supporting rows underneath (Rating Lost per Wash, Reported Rating, Unpressed, Rating After Pressing, Reported Rating, Pressed, Margin, Unpressed, Margin, Pressed, Washes to Target, Unpressed, Washes to Target, Pressed, Washes Gained by Pressing and Margin When New) before acting on the headline — they are where an implausible input usually shows itself first.
5. Reset to defaults returns every field to the reference case, which is the quickest way to check whether a surprising result came from the tool or from an input you had changed earlier.

Where this is used

• Process planning — establishing Rating at the Claimed Wash Count before a trial is booked, so machine time and material in Finishing, Coating, Lamination & Functional Performance are committed against a calculated figure rather than an estimate.
• Costing and quotation — Rating at the Claimed Wash Count is an input to the cost sheet, and quoting from a worked number rather than a remembered one is what keeps a margin intact.
• Troubleshooting — when the floor result drifts from plan, entering the measured values (starting with Initial Spray Rating) shows how much of the gap in Rating at the Claimed Wash Count each variable explains.
• Teaching and study — the accepted ranges bracket normal Finishing, Coating, Lamination & Functional Performance practice, so moving one variable at a time shows the shape of the relationship rather than a single answer.

Assumptions and limits

• A linear decay is fitted from two points and it is a convenience rather than a mechanism: real spray rating falls fastest in the first few washes as loosely held finish leaves, then more slowly, so a rate fitted over five washes will be pessimistic at fifty and one fitted over fifty will be optimistic at five. Fit across the range the claim covers. The rating scale itself is ordinal and coarse - the rungs are 0, 50, 70, 80, 90 and 100, and nothing lies between them - so the continuous figures here are an interpolation used to compare and project, and the reported values are what an operator would actually write down. Reactivation gain is a property of the chemistry and the care applied: a modern non-fluorinated repellent typically recovers less than a long-chain fluorocarbon did, and a low-temperature tumble recovers less than an iron. Measure it rather than assuming the default. Nothing here addresses the durability of the substrate itself: a fabric whose surface has been abraded or pilled by laundering will spray-rate poorly however intact its chemistry, and that damage does not reactivate.
• Every input is bounded to the range normal practice occupies (Initial Spray Rating 0 to 100 AATCC, Rating After Test Washes 0 to 100 AATCC and Test Washes 1 to 200 nos, and so on for the rest). Those bounds are guard rails against typing errors, not a claim that the formula fails one unit outside them.
• The calculation is deterministic: the same inputs always give the same result. It carries no allowance for machine condition, operator skill, ambient conditions or lot-to-lot material variation unless an input above explicitly represents one.
• Nothing is sent anywhere. The maths runs in your browser, so the numbers you type never leave the page.

Questions people ask