NavList:

What you have effectively done is deposit a carbon layer onto the glass. The deposit of thin films onto substrates to control their optical properties is a huge subject that overlaps with chipmaking... You can deposit almost anything as a thin film with the right equipment to achieve almost any effect! Interestingly what you have done is not far from the birth of thin films which was when they (Raleigh) that tarnished old mirrors reflected more light than Shiney new ones!

So yes, there are many coatings that will do what you ask. Do you want to deposit them at home? Do you want someone else to deposit them for you or just by them? There are labs all over that will custom make coatings... All things come down to the amount of money you wish to pay!!!!