If visitors want to download a catalog or some instructions, do not force them into signing up, developing a password and going through that. Give catalogs away, manuals away and let them see as much as possible, then ask them to login if they wish to continue. Do not drive them away with bothersome logins.
Note: Some of the catalog companies online have noticed that when visitors come to see their merchandise and are asked to login, potential customers back out and go elsewhere. They have now added and written in their program, “Stop, wait, look around, shop if you wish before you leave”, and then allow the visitors to look at the website without logging in. Only when they are ready to buy something are they again asked to login. This is still bothersome and unnecessary for new visitors. Take it off your website and make it easy for newcomers. Give as much away as possible without bothering the visitor.