Two of the questions I get asked the most by newer collectors is "Which Side of the Comic board is the one to put next to the comic" and "Do the Comic boards work as advertised".

There are several Factors to consider when making this decision, Older Comics tend to have High acid ink and paper in them, by older I mean 1995 and back to the 1890's and before.
Newer Comics and Magazines have switched paper types and printing ink types, they are less likely to have some of the problems older printing sources have. At times on the older comics you can find two different paper types in the Same printing of the comic. Also, Ink types were changed from one printing to the next and the brightness and quality of the ink varied considerably.

Here are some tips, on Storing and Saving Older Comics:

Comics Books should be stored in cool, dark places, as sunlight can bleach the pages, and heat and moisture can also damage them. Sunlight can also react with the paper, causing it to "yellow", as well as having a bleaching effect on the inks used within the comic.

Some collectors advise against using backing boards, as these are sources of acid which can react with the fibers of the comic book paper, eventually destroying a comic. If backing boards are used to store comics, collectors advise using products marked as acid free.

A backing board (or backer board) is a comic book-sized piece of cardboard designed to keep comic books flat, and to protect them from bending during shipment or storage.
Backing boards became popular during the comics boom of the 1990s, when most collectors became interested in the storage and preservation of their comic books.
Comic book collectors refer to a comic book that has been placed in a polypropylene bag with a backing board as "bagged and boarded."

**Be Sure your Using Acid Free Storage Materials, if they are not Certified they are Not Acid Free.
Even among the Certified Materials there are differences and levels of certification, so caution is advised.
Read the materials about every individual product carefully**
 
Grades and Types of Backer Boards

There are three grades backing boards:

    1.    Chipboard - A pH-neutral backing board that is 16-20 points thick. Chipboard contains acid and is recommended for short-term storage. These are white on one side and bare cardboard on the other.

    2.    Acid-free - Acid-free boards trap and neutralize acids in paper that would otherwise permeate and slowly destroy them. These boards are usually 20-24 points thick and white on both sides, one shiny, one matte. Acid-free backing boards are recommended for long-term storage.

    3.    "Super" acid-free - For archival-quality protection, these acid-free backing boards are buffered with calcium carbonate, which prevents the board from breaking down, and are white on both sides, one shiny, one matte. These boards are the thickest, at 24-28 points.
Some Comic Backer Boards are considered to be Super acid-free being made from a 24 point solid bleached sulfate, coated on one side buffered with 3% calcium carbonate , and are precision cut to size.  Backing boards are white on both sides, one shiny, one matte, the shiny side is the side coated with 3% calcium carbonate, and should be placed next to the comic book.

Comic Book Extenders are based upon the Super acid-free Comic Backer Boards.
Comic Book Extenders are made from a 10 point white solid bleached sulfate, coated on two sides with a buffered 3% calcium carbonate, and are precision cut to fit inside the comic book.
Comic Book Extenders have almost 3 times the Alkaline Reserve (Acid Absorption) of normal Backing Boards.

I have spoken with many collectors, 80% believe it helps in age prevention and decay prevention, it also helps reduce the Yellowing process of the pages as well. There are other collectors that say it does no good and is a waste of money.
I personally use these products for my own collection. In my own non scientific way I ran a little experiment. Most collectors of old Comics and Magazines can tell you that when you open an old unprotected Comic, you will be able to Smell the acidic nature of the paper and ink, at least I can.
I put three comics into the experiment all were the same age and printed the same way by the same company. I put one Comic in a Bag with Extender Boards and one into a plain comic bag with a normal Backing Board, and one into a plain comic bag with no board at all.
After 6 weeks I checked all three comics.
In the Comic Bag with no board, I could smell the acidic presence when I opened the Bag almost immediately.
The Comic enclosed with the Standard One Side Coated Backing Board had allot less of the Odor than the non-Backed Comic.
The Comic with the Extender boards was almost odorless, not completely but very close.
Thus I concluded this was something I wanted to use for my own collection, based on the smell alone.
It's not High Science but it was rather convincing. I then invited three collectors to see if they agreed with my proboscitus (nose) findings, to my surprise they all agreed with me.
I then did a little more research and found, there are several Libraries using the same type of boards for Archiving older books and newspaper files including the Library of Congress.

While these are not inexpensive, if you want to extend the life of your older more valuable Comics  and Magazines it could be to your advantage to use these methods for storage.

Please note the backing board information is from BCW who manufactures these types of products, test results are from independent testing sources. These Boards and Extenders are Certified Acid Free.

Thank you for reading and i hope this answers some questions for you.

Pauline and James Wessa
Ethers Pawn Comics