Cotton vs. Polyester

I suppose polyester is the pariah of fabrics. This synthetic may never get away from its image of 1970s double-knit, leisure suit fashion. But polyester has a place in the history of Aloha shirts, whether we like it or not. Starting in at least the 1970s, clothing designers began to use either 100% polyester or a polyester blend in some of their fabrics. It seems the pure polyester fabrics were more prevalent in the 70s, as what I encounter for later-era shirts are mostly poly/cotton blends.

I suspect most purists will reject any shirt as vintage if it has any polyester in it. So if you are trying to create some criteria of what "vintage" means, then it may be fair to say any shirt with this synthetic fabric is excluded from this coveted criteria. But do note that rayon, while completely accepted as a vintage fabric, is also a synthetic.

So what if you encounter a shirt without a fabric label that might be polyester? Is there a definitive test? I had such an encounter with this shirt.

I found this shirt at a thrift store. I suspected it was at least part polyester, but there were some attributes to it that had me think it might be from the 1960s. The label was missing, but it appeared to be a full-sewn in one, that is indicative of a vintage shirt. The metal buttons also had a vintage patina to them.

The fabric of the shirt was very light weight. All of the 1970s polyester shirts I've seen tended to be heavier weight. The weight of the fabric felt like a woman's summer scarf - very light and airy. Upon closer inspection, there seemed to be surface imperfections to the fabric, which are indicative this was not polyester. The shirt, while soft, didn't didn't seem to have a richness that you find in silk or rayon. But the shirt appeared to have been starched, which might account for the coarseness.

The fabric had a wavy look that suggested this might be imperfections.

My rule is if I have doubts on the vintage of a shirt, then pass on it. But I was intrigued by this shirt for some reason although I had my doubts. There were a few other clues as well. I tightly squeezed the fabric to see if it would hold wrinkles. Silk and rayon will hold wrinkles while polyesters won't (or so I've been told). Sure enough it did hold some wrinkles, but not a lot. So this test was inconclusive.

So I opted to pony up the four dollars and get it and find out more about this item. After bringing it home, I hand-washed the shirt to see of the coarseness (that I attributed to a possible starching) would go away. No dice. Upon further inspection of the loose threads on the inside seam, I saw some unraveling that looked more like fuzziness than stringiness. Ok, this really suggested polyester. But there was one definite test left.

I snipped off some loose threads from the seams and but them in a fireproof container (in this case, the bottom of an empty soda can). I then applied a flame in the definitive "fire test". If a fabric is silk, then it will burn to ashes and smell like burning hair. But if the fabric is polyester, then it will melt and smell like burning plastic.

The flame test.

I think my sample was too small to detect a smell, but the thread burned down to a tiny ball of hardened plastic. This was definitely polyester. In retrospect, the fuzziness of the unraveled fabric was likely a solid clue that the shirt was indeed polyester. So a lesson learned as to the value of carefully examining the seams.