I see questions about matting and framing now and then. Perhaps this information I wrote out for another member will help others. Doubtless it has typos etc. but the main ideas should come across. Additions and corrections welcome :)

Anodized aluminum frames are chosen for stability and inert qualities - something wood just does not have. Wood is acidic and hygroscopic - not wanted around autographs. These metal frames are available in sections or cut to order in a wide variety of colors, finishes and profiles. One can save a LOT using them and get near-museum results. All mats and materials used should be archival, acid free etc. The aluminum frame mat sandwich system is roughly as follows (from memory 35 years ago) - from glass down as seen on the wall finished:

If a large project you might need spacers (online or ask framer) to insure no touching of items to glass, if smaller with double mat not necessary

The "top mat" - the one you see most of and has the largest cut window. In the attached digital scale example it is a color that matches a darker color predominant in the litho but not overpowering. Muted/sedate. Very mild texture. If say a 16 x 20 frame (just a number - not for the example) this would be cut 16x20 with window to allow "secondary"or "trim" mat to show with signed item. Of the litho - it has intrinsic collectible value of its own - I always try to get a period image or original still etc to frame with a signature instead of a knock-off.

The "secondary" or trim mat. Same texture perhaps. Different choices cost about the same - make them. Adds texture. This goes under the top mat and has a slightly smaller window (maybe 1/8" to 1/4"- there standards you can look up). In the attached example below it is red/orange, ties together both the original color litho and album page ink, it matches both Bowie's hair and the ink so that they sing and I can get away with using the color litho because the ink, of which there is more than hair, will be strongest (esp with trim color for cohesion). A b/w photo still would be boring here and one could not use the red secondary or trim mat because there would be nothing to match in the b//w photo. Nothing to tie together. This mat is cut 16x20 with slightly smaller window (to show "trim") to conceal coming corners on signed item (you might be using a reversible hinge). IF no room for that - say, a "tight" cropped photo where you need to show almost the whole thing (never cut off hair on people or alter compositions etc with a mat), then mount from behind with a hinge which you can learn how to make with Linenco or like products online. This gets stuck to the item(s), corners preferred where possible, Mylar, Linenco or the equivalent - no sticking anything - manually held in place is best.

The mounting board (which you don't see) to which the signed item is attached with corners or a hinge etc.. Museum board in cream, its textureless, sturdy 4 ply would be nice if a large project, that you are attaching the item(s) to with either corners or hinges (2 hinges at reverse top of not wider than say 10" - you'll see online). Also would be 16x20 with no window in our example.

All of this gets secured together - see online for detail how with Linenco acid free linen reversible tape. This is the "sandwich". They probably sell hinges and all this premade now.

The backboard is just acid free museum foam-core that goes behind all before you close the frame. No paper etc necessary - the foam-core, if thick, will act as a buffer or moderator to changes in RH or temp.

Assemble sectional aluminum frame tightly, place glass in, use compressed air to remove the dust because you've just cleaned the glass inside with the appropriate cleaner (many leave chemicals - search online).

Place in sandwich face down checking no dust on anything - a finals blast of air (keep can upright!) then drop in from an angle. Check for dust - redo if necessary.

Insert foam-core backboard then use the aluminum pressure clips - close and finished but for wiring. Always over-wire - stronger weight then needed. Do it neatly - see online. Quality wire won't degrade. Now it is plastic coated! :) Always use a hanger stronger than needed. You want the work to hang down a bit at an angle with only the bottom touching the wall - they sell plastic protectors to stick on the  back bottom 2 corners and save your walls. This will prevent it from getting dusty and also prevent most problematic reflections as well.

Whew!

Our example below:

Original rare USA color 8" x 10" heavyweight lobby still, photo by Chuck White, from the initial release of the Man Who Fell to Earth, 1976. Mint, with a heavyweight paper stock album page measuring 5" x 7", signed with red felt tip pen and dated in pencil on the Verso, "April 26th, 1976". A "Thin White Duke" concert that night in Sweden.
Bowie hated blue ink, and many of his nicer early signatures are in red ink of one sort or another. This is 1976 and he was experimenting a lot with style and even the content of his signature. This has the flavor of his fuller earlier 70's signatures, many elements in play, but with the basic abbreviated construction to come in later years. This hybrid signing style, these forms and relations, can be seen as late as 1979 and even a bit beyond. This example has many traits that are typical of a genuine Bowie, despite the unusual appearance compared to the so-called "normal". I am very proud of this set. I have vintage Rip Torn in 5" x 7" that I nabbed for $1 shipped, but I feel it might detract.

This signature can be seen in the exemplar files at a site I have contributed to - davidbowieautograph.com - it is listed at as one of the first "Bo° 76" signatures ever and one of only perhaps six dated 1976 examples shown.

Anything prior to 1980 is just TOUGH. Mid 70's very tough indeed. And this is his typical early red ink, and huge, and darn pretty. Thank you Bjarne!