Carbon dating. I have always wondered how it can separate the form from the substance. Are you telling me we can date the time this fabric was woven together, or the date its substance came into being? I am a skeptic when it comes to this science, because those who practice carbon dating evade this funamental question.
I remember they took samples from the patches that were added later on.
It’s pretty simple. Organisms accumulate carbon until they die. Then it slowly deteriorates at a known rate. Measuring that tells us the age at which the cotton was picked.
The fabric is linen, which comes from flax plants. C-14 dating would essentially be dating when the flax plants were harvested (that is, killed). That’s when they would have stopped absorbing C-14 containing CO2 from the air.
The carbon dating was done on a portion of the shroud that had been charred in a, I think, 14th century fire.
It dates from the time the flax (or cotton - I can’t remember what the shroud material is!) that was used to make the linen stop growing as a plant. When it was harvested it stopped absorbing Carbon and its isotopes. Well within measurement error from time of harvest to making of the cloth.