Projector tutorial: part 2

So, with the size and aspect of the screen decided, the next step is not to go to a retailer and spend like mad. It’s far better to build it yourself, especially when there is a DIY product, called ‘Screen Goo’, that will ensure the success of your project.
 
After speaking to several professional AV retailers, we were convinced to give this product a try, and can now vouch that it delivers excellent results.
 
1. The first step was to build a frame of the required dimensions, in this case 137cm x 107cm, a size that complements the 4:3 resolution of the HP EP7112 projector used for this tutorial. The framework is constructed from 42 x 19mm PAR pine, with a 3mm thick sheet of MDF used for the screen itself. The corners are mitred, and 75 x 75mm steel L-brackets were used to add strength. Although the timber does not have a great deal of structural rigidity, the desired outcome is to create a lightweight unit that is safe to hang on a normal plasterboard wall.
 
2. After the MDF sheet has been glued and screwed to the frame, a 40mm wide border has been added around the edge. This is not just for aesthetics, it will be painted with flat finish paint, preferably black (however my interior designer warned me that it had to be slimline and chocolate-coloured or the screen will stay in the workshop) so as to reduce the ‘halo effect’ from the projector.
 
The ‘halo’ effect is a grey band of light around the outside of the projected image, caused by stray light being bounced off the edges of the mirrors on the DLP chip. It can be overcome by having a black border around the screen, so the halo falls on to the border and is ‘absorbed’. The border should really be about 100mm wide.
 
3. The screen is now ready to be coated with Screen Goo. Screen Goo is a specially formulated, highly-reflective acrylic paint, designed specifically for DIY construction of high-performance projection screens. It can be used on any smooth paintable surface, and can even be applied directly onto a wall rather than on a separate fitting. There are seven Screen Goo coating products, which can be mixed and matched for nine different coating combinations, to provide the ultimate performance with any projector -- the manufacturer’s website has a 'ready reckoner' to help select the best product for your specific requirements.
 
The site blurb says that, Screen Goo promises exceptional colour fidelity, positive gain with minimal hot spotting, and industry-leading horizontal and vertical off-axis viewing characteristics’. Sounds promising.
 
The product used here is Digital Grey in both primer and top coat. Grey screens have the ability to make the most of the projector’s contrast ratio, making darker tones more rich and realistic, but require lower light levels for optimum viewing. In a ‘real’ home theatre, with low to nil ambient light and a 2.5-metre projector throw, this choice is perfect.