Are front surface mirrors mandatory?

[TheBoiledDumping]

I've taken a interest in DIY Projectors, but 1 thing is stopping me from continuing my build. If you noticed from the title, are front surface mirrors mandatory? What are the consequences of using a regular mirror? Would the image not come out properly, maybe distorted a bit? I hope whatever I wrote made sense 😛 I really like newtonn2's projector on Instructables: DIY Projector using an OHP
I'm trying to base mine off his a bit of his. 😉
Thanks

 

[diarav]

Check out this link for the reasons:
Astroprof’s Page Speculum Metal Mirrors

Scroll down to the section where the front coated and rear coated mirrors are compared.