One thing that I believe a lot of folks do not know of, is that 'white' eight ply museum quality matboards are available.
It's an expensive material, however, if you look around , you'll find both art and matboard dealers, will give a good (from the photographers and artists perspective prices when bought at wholesalers so, if you have a valid tax number for your company, or know of someone willing to help you buy with theirs, do it and treat it as the very special material it is and enjoy working with it.
If you are showing at a gallery or for a contest where framing is mandatory, frame using whatever format you want to use, and use these heavy (thick) boards, which in most cases tells the judge(s) you are seriously pursuing your art - photography, which may give your work an invisible leg up over, The Competition.