Lie many people, I do noy wash and iron my own shirts. I don’t like to do it, and the local drycleaners do it for $1.25…so I let them do it. Lately, I have been wondering if this is a good idea…my shirts seem to be shrinking? Most of my shirts are cotton-polyester…and I thought that you might have a little initial shrinkage, but after a few cycles, it should stop. But now I can see that my sleeves are too short…and since it is unlikely that my arems are growing, the sleeves must be shrinking.
Do commerical laundires cause cotton shirts to shrink? Does it continue?
I guess I’ll have to iron my shirts myself!
I have my dress shirts laundered. They come back nice and pressed and the sleeves are as long as they were before. Pretty good deal, if you ask me.
It depends on how the laundry washes your shirt. Cotton itself is unlikely to shrink much under heat; even if it does you can generally tease the fabric back out again. However, synthetics (polyester etc.) definitely can shrink under heat, so that’s probably what happened to your cotton/poly shirts. Some of the processes commercial laundries use at higher temperatures can significantly shrink the fusing (the synthetic interfacing which keeps your collar, cuffs and sometimes placket stiff). This is why it’s generally suggested that you wash your dress shirts at home.
If you wash your dress shirts at home, wouldn’t pure cotton be a better option? It doesn’t seem to be drastically more expensive than cotton/poly if bought at sale prices or ebay etc., and will generally be more comfortable and wear longer. In addition to not shrinking at the cleaners 
Backwards, but I suspect that’s just a “posting slip-up” on your part.
If you’re sending your shirts to a laundry, go with all-cotton. If you wash them at home, go with a cotton/poly blend. I always washed my own cotton/poly dress shirts (back in the dark days when I worked), and if I pulled them out of the dryer one at a time (i.e., never letting them sit in a pile) and hung them up right away, they never needed to be ironed. Cotton, you gotta iron. A lot.
Since these are questions with factual answers, I’m gonna move this to GQ.
Cajun Man
for the SDMB
All of my shirts go to the laundry. I’ve never had a problem. Of course, all of my shirts are Hawaiian shirts, especially my work shirts. I love my job! 
Have you gained weight, or started working out, since the shirts were new? Even a slight increase in shoulder mass will make the sleeves seem shorter.
I just bung them in the washing machine and then the dryer. Are you sure you’re getting your own shirts back?