The test can return no answer
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The sequence escalates before it concludes
Five specimens are tested first. If there is one burn time under 3.5 seconds, or an average under 3.5 seconds, five more specimens are tested from the same direction.
And the Class 3 finding requires more than one reading
Stop testing and assign the final classification as Class 3 only when there are two or more burn times with an average burn time of less than 3.5 seconds. Only when, in the rule’s own words.
Which leaves one case the escalation cannot resolve
If there is only one burn time out of the ten test specimens, the test is inconclusive. The fabric cannot be classified.
That sentence is the most unusual thing in this part
A federal safety standard with a defined outcome of no result. Not a default to the safe class, not a default to the permissive one. No classification.
And a single reading above the threshold is treated differently
A preliminary Class 1 may be assigned where there is only one burn time and it is equal to or greater than 3.5 seconds, or where there are no burn times at all. So one reading can pass a fabric and cannot fail it.
Which is an asymmetry with a clear logic
A specimen that does not sustain a flame is evidence about the fabric. A single fast burn among nine that did not ignite is not yet evidence about anything, and the rule says so instead of averaging it away.
This is the principle this catalog runs on, written into a regulation
An absent answer degrades gracefully. A wrong answer gets acted on. The standard would rather report that it cannot classify a fabric than publish a class it does not have the data to support.
Three findings in this library now sit together on the same question
The care labeling rule makes a blank into a permission. This part makes one data point into no answer. And one column in this catalog gives a number without saying what the number is of.
The first two were designed and the third was not
Which is the difference between a record that handles its own gaps and a record that has them. A designed blank is usable. An undesigned one has to be left alone.
And the final classification takes the worse of two attempts
The final classification shall be the preliminary classification before or after refurbishing, whichever is the more severe flammability classification. A fabric does not get to pass on its better day.