Hair ties don't stay in very well, there fine for a day or so before the show to keep crests clean. First good scratch and they are on the ground.
I used pink hair tape on them a few times and on my polish as well.
The best thing to do is use pop bottle waterer's. Keep in mind they will freeze in the winter though, unless you have heat lamps running close to them.
I don't know what you are presently using to water them. I use a lot of the plastic gallon waters with the red bottoms, there is not much space for them to get the crests wet unless you have a few of the "duck" silkies like I do. The red bottom gallon waterer's I use in the outside runs.
I have attached a photo of a pop bottle waterer, these are the ones that hold a lot more water and are made for larger bottles. I don't know if you can still buy the large ones are not, these are about 10 years old. I use these in all my coops and houses, these are galvanized steel but I also use the plastic ones in the smaller houses, but the plastic ones don't hold up as long, these last for years.
Large steel bottle water's to left. No wet crests here. But I would like to add, there are some silkies who just love to play in the water and no matter what kind of waterer you use, they manage to get the crests wet, I have a few of those too.