When I was at the technical college, each semester I discussed correct lab attire on the day of the basic safety lecture. Many of the lab experiments the students did had little or no chance of causing harm to a student incorrectly attired. (Several experiments used only room temperature water So they're was no danger b to the students.) NSo, while I would point out to the students that they were not correctly attired, I didn't kick them out of the lab that day, but would say that the rule would be strictly enforced on any days that there were lab dangers. They had a schedule I supplied (and posted copies of) that listed which experiments the attire rules would be enforced for.
So, each semester, and in each lab section, I would have one student show up on a day when I'd reminded them the clothing rules would be enforced, wearing tights or a low cut top (my written rules were for a crew necked shirt or higher,) or a sleeveless shirt. I would stop them at the door, and say they couldn't do the experiment since they were incorrectly attired. Of course the student would act like this was news to them, but I had taught it, posted it, and reminded them of it. So it wasn't news. But in the same way as a small child tests limits with a new babysitter, students will test limits. And the student who was inappropriately attired who got angry at being kicked out would be asked "if your boss said don't wear flip flops to work and you showed up for your shift wearing flip flops, what would you expect to happen? The students would always say they'd get fired. And if come back with, I'm only sending you to get appropriate clothing, not failing you for the course. That student would leave, and almost every time within a half an hour would be back wearing appropriate attire.
I did use the terms crew neck and long sleeved to describe the needed shirt, but I also kept disposable sleeves on hand, and I did use the term skin tight to refer to how the pants that were not acceptable fit. I'd explain that tight pants, regardless of what they are called, skinny jeans, tights, leggings, etc. are verboten because they would hold acid or other harmful chemicals right on the skin, virtually guaranteeing skin damage before they could get them off in the shower.
When the lab was remodeled to make a handicapped accessible lab station, I insisted on shower curtains around the safety showers, although those were Velcro-ed back out of the way so as not to restrict access to the shower.
I found that I would have to be hard-nosed in enforcing the rules only once a semester, but in each section. The student who ignored the rule and the reminders and got kicked out for that lab provided enough of an example that nobody else would try it that semester. But the next semester, even if the same students, somebody would test the limits again.
My students were all adults, but some were rather young adults, and they would tell me I reminded them of their mothers: "You think I can ace everything, but you won't let me get away with anything" and "what? Do you have eyes in the back of your head?" So I decided that, like that old movie where two women started using a dog training book to guide how they treated their husbands, I decided to use the child training techniques taught to elementary school teachers. I didn't announce that to them, but they did act a lot like little kids trying to get away with stuff.
I also had to learn what to say to get cooperation. I'm 5'2" tall and very slight in size, so I physically intimidate nobody. And in some classes the students would be totally obnoxious and defiant from day one, and I had to find out how to prevent or stop those behaviors and to turn them into cooperative students. I hit upon asking the students who worked or were raised on farms, if they enjoyed working on the farm. They'd always say yes. Did they follow safety rules when working on the farm? A definite yes. So following safety rules doesn't have to mean to can't have fun? Not on the farm it doesn't. (Or in wood shop, machine shop, cooking classes, etc, whatever seemed like those particular students would relate to.)
So I'd tell them that lab was supposed to be fun. It was designed for theme to be able to see and do they chemistry we tracked about in lecture, and that should be fun. But getting a chemical burn or setting fire to one's hair isn't going to be fun, so I was going to teach them behavior each week that would keep them safe doing that days experiment, so that by following the safety rules they could be free to have fun. Once I learned to say something like that, I used it every semester and I never had defiant students after that. I had cooperative ones.
And getting them to cooperate in keeping themselves and all the other students safe in lab, truly did make keeping them safe easier. They respected that safety was my goal and was the only way the labs could be fun. And they really liked that I thought they were supposed to be having fun in lab.
And the crew neck shirts totally eliminated having to explain to the why to the student. I once had a young woman in lab, who had just had breast augmentation surgery and wanted to show the results off, that she really didn't want a burn in that area. That's a conversation that can be nothing other than awkward, and might get me in trouble and would certainly get a male teacher in trouble. But saying a crew neck line or higher is required to cover skin and prevent damage, made such awkward and potentially career ending conversations completely unnecessary.
My students course evaluations always said they thought that the lab was the best part of the course. And if asked they'd say they weren't afraid in lab because Meg taught them the right way to handle chemicals and stay safe.