I get asked this question quite often: Does the screen come with a black back? Well, a lot of screens do, so why would people be asking this question?
Well, they have been "told" a black back is better, because it doesn't let any light come through. A lot of companies don't even bother to explain why that would be better, so let me tell you why it's better to have no light come through the fabric.
How light through the back of the fabric will impact your projected image
The best possible home theater experience is achieved when there's no light that can interfere with the light coming from your projector. So, light coming through the back interferes with the images, because it makes the image look washed out. That means that the colours aren't as deep and vivid.
So your goal is to have no light coming through the back of the fabric.
Why a black back doesn't solve the problem.
As we have seen above, the issue is not the colour of the back, but the amount of light that comes through. Some companies have cleverly marketed the black finish on the reverse side of the projection fabric as the black back that lets now light through.
However a very thin piece of fabric - even with a black back - can let light through. And - the right piece of fabric with 2 white sides can block out any light.
Which brings us to the question: what does have an impact on the light coming through the screen?
Opacity and why this is more important than the black back
The answer for the issue is the term opacity. When the opacity of a material is 100%, it lets through all of the light. When the opacity is 0%, it blocks out all the light.
So what we are really looking for is a material that's 0% opaque. Because this material would black out all the light that's not coming from the projector. Regardless of the colour of its back.
No projection screen manufacturer gives opacity values, so now what?
How to choose the right fabric, without the right information
Luckily, there is a way, but it will involve some work. Failing the right info, you have to do your own research. There are 2 ways:
Call your potential supplier and ask for a guarantee. They should know if the material is 0% opaque and if not, they have to find out for you.
Ask your supplier a fabric sample. Take a bright torch and hold the fabric against it. If no light comes through, you should be fine. Be careful not to use a light source that becomes very hot. The material might melt!
So when you go shopping for your projection screen, you know now what to look for and how to test the material. Have fun.
