Let's start with a few basic facts:
1- The majority of ADA signs being manufactured today are made with the raster Braille method- i.e. the Braille is formed by drilling a hole and inserting a small plastic bead.
2- Photopolymer signs (fabricated by exposing UV light to a photo-sensitive sheet) are being called for by an increasing number architects and designers.
3- Fords are better than Chevys.
The debate over the superiority of these two competing methods of fabrication reminds me old men debating why a Mustang is superior to an Impala. The key to understanding these arguments is knowing what everybody drives- in other words, what's their financial stake.
The fact is, both are perfectly acceptable methods for fabricating ADA signs. And both have distinct advantages. I'll try to explain a few of each. Raster Braille signs are the most efficient method for producing short-run signs. If you need 15 office signs in a hurry, you should expect to pay less than $30 each for a basic Raster Braille sign in the color of your choice.
The same sign fabricated from photopolymer could cost 50% more because of the materials cost and the additional setup.
One distinct advantage of photopolymer signs are that they are "top-coated" with paint which seals the entire surface of the sign. This can be helpful in medical environments where rigorous cleaning is required.
Now let's debunk a few myths. Some people claim that the braille dot is too flat rather than domed on photopolymer signs. This was a problem years ago when the technology was evolving, but has largely been corrected. On the other side, critics of raster Braille claim that the signs don't hold up as well. This idea has been propagated but is not based in reality.
Who is winning this debate and why does it matter?
If I was keeping score, I'd say the photopolymer folks are winning the debate. Companies like Nova Polymers (a plastics manufacturer) have spent a huge amount of money lobbying groups like the American Institute of Architects. They have managed to convince many of the superiority of photopolymer signs and for this reason many architects specify this type of sign. This matters because it causes the price of ADA signs to be higher- especially on smaller jobs. The losers here are businesses who have to purchase a more expensive sign.
The key to understanding this debate is that both types of signs are perfectly acceptable ways to create high quality ADA compliant signs. If somebody has a really strong opinion, just remember its Fords versus Chevys.