What is Archival Picture Framing?

Archival (ahr-kahy-vuhl by dictionary.com or r-ki-vul by me ) picture framing is a term that makes many eyes glaze over.  It is based in science and can be as dry as reading any tech manual.  And, there are disagreements as with most scientific opinion.  It was once relegated to museums and a few picture frame shops that knew the subject and had images to preserve “for the ages”.

Then a funny thing happened, suddenly everybody was selling “acid-free” materials.  They quickly intimated that there was no longer a need to worry; with the introduction of yet another miracle cure called calcium carbonate buffering (sort of Maalox ® for mat board) mat board and backing and tape and glue was not a problem any longer.  Terms “archival quality”, “conservation mat board”, “museum board”, “rag mat” and many other terms were increasingly used “loosely”. 

Our best authority on this subject is the Library of Congress.  They set the standards.  Following the component picture below, I have paraphrased what the Library of Congress states (with my comments in blue):

1.    Either a window mat or “spacers” that hold the object off of the glazing must be used.

Yes, you need to keep the artwork off the glazing so moisture does not damage the art/object.  As the LOC points out, this is especially important with photographs because they will actually stick to the glazing.  

2.    The window mat and a “back mat board” should be made of cotton rag or chemically purified wood pulp and “must test negative for lignin”, the substance in paper that creates acid.   

Lignin is an impurity found in pulp.  It contributes to the formation of acid.

Notice they have added a “back mat board” that they consider necessary even though there is a “backing board”.  Their aim is to incase the art in its own world within the frame materials.  

3.    It must be acid neutral, have a ph value between 7 and 8.5.

Pretty standard values defining acid neutral (often called acid-free) materials.  But there is a “however”.  I quote:  “The addition of buffering agents to unpurified wood pulp papers does not render them fit for preservation use.”  In other words, “acid-free” mats may be ph neutral at time of manufacture when calcium carbonate is added.  However, if they have not gone through the additional step of being cleaned so they are lignin-free, they will become quite acidic in a relatively short period of time.  

4.    The mat board should be, at least, 4-ply. 

I believe this is self-explanatory.  However, since they also have a “backing mat board”, I assume they want 4 ply for that.  I believe this is really a specification so the component that holds the art is stiff and stable.  

5.    The mat should be secured to the back mat with water activated linen tape.

OK, now we get down to the how “archival” do you want to be.  Yes the mat should be secured with tape.  And, most assuredly, must be strictly framed according to these specifications if it is a museum grade object or has some other intrinsic value.  The problem is that they have not found a self-adhesive tape they feel is suitable for their kind of archival framing.  I believe this is because of two reasons.  One, there are certain chemicals in self-adhesive that could affect a print, especially over such a long time.  However, the other key factor is that self-adhesive tapes are quite hard to remove without causing some damage [water activated tape only has to be remoistened, a problem for some watercolors and other media sensitive to moisture however].   

6.    The object being framed should be “hinged with long-fibered Japanese tissue adhered with wheat or rice starch paste” or corners\\strips of acid-free paper or polyester.

Again, as in 5 above, we have the problem of chemicals and removing the tape. Self-adhesive tapes have tried to alleviate the chemical problem by using ph neutral glues and usually come with linen or polyester plastic carriers.  Removal can be difficult.

We have the added problem that technically the print should be attached with a tape that will break before the print itself rips should the picture frame fall.

7,    Glazing should only be glass or acrylic sheets.

Glazing, glass or acrylic, comes in UV filtering versions.  The LOC, however, does warn against the following:

        Plastic can develop a static charge that attracts some media.  For example, unfixed pastels, charcoals and pencil drawings.

        “Avoid non-glare etched glass; it is etched with acid and may not be completely neutralized”.

8.    The Glazing should have added UV filtration.

Even with UV filtration, keep the framed piece out of the direct sunlight.  Visible light can damage picture framed pieces quickly

9,    Picture frames should be wood or metal.  If wood is used, the rabbet should be lined with aluminum or polyester tapes with acrylic adhesives.

The rabbet is the part of a wood picture frame stretching from the front to the back of the frame that holds the glazing, mats, etc.  The wood is exposed and since wood is acidic, it should be lined.

10,   The entire unit of glass through backing board should be held in the frame with pins or brads, “never with pressure sensitive tape”.

Nothing to say.  It should.

11.    If the frame will hang on an “outside wall”, it should have a moisture barrier (polyester film or polypropylene) should be placed behind the backing board.

True, but dependent on the amount of insulation used in the structure and temperature/humidity control.

They also mention that hanging picture frames over fire places or radiators can be a problem.

12.    The picture frame should have a “dust cover”.

This is a sheet of paper that is glued to the back of the picture frame.  It does keep out dust and does provide a bit of help keeping the temperature and humidity constant in the frame.

One more thing, even the government has their disclaimer:

The preservation procedures described here have been used by the Library of Congress in the care of its collections and are considered suitable by the Library as described; however, the Library will not be responsible for damage to your collection should damage result from the use of these procedures.

1.     Ditto for me.

Source: Preservation Guidelines for Matting and Framing, Library of Congress,  www.loc.gov/preservation/care/mat.html

There you go.  That is a fairly complete, non-technical listing.  In practice for everyday picture framing, you will have to decide which of the 12 points you follow.  If you are doing temporary framing or the $2.00 tourist piece, you can probably ignore them all.  As for me, I do the following for my personal picture framing:  

1. Yes.  I always use a mat or spacer.

2. Yes, for the mat.  I always use Cotton Rag unless I need a strong color, then I use an Archival paper mat.  Always archival, always lignin free.  I do not usually use a back mat board and then another backing, simply a good archival backing like Nielsen Bainbridge Archival Foam Core.

3.  I always use ph neutral products throughout.

4.  I always use 4 ply mats or thicker.  I am partial to 8 ply cotton rag.

5.  I confess that I do use self-adhesive tape.  Usually a linen self-adhesive or our “Framer’s Tape”.

6.  I have used paper hinging tape on a couple pieces but I usually use our Framer’s tape.  I do not own art in the price range that I am concerned about self-adhesive and I have minimal contact between the tape and the art work.  I like the art, some of it is mildly expensive and I have had many of my pieces for decades.  The archival mats still look so clean and fresh 10 and 20 years later, I am not going to change them.

7. I usually use glass.

8. I always try to use UV filtering glass.  With some small pieces that are not exposed to light, I ignore it.

9. I should line the rabbets of my wood picture frames, but I do not.

10. I always use “glacier points” to hold the whole thing together.

11. I have not used a vapor barrier.  I do not have a situation that would require it.

12. I use dust covers on all wood frames.  I do not on metal (the springs used in metal picture frames make a good seal.  I have used a few plastic picture frames but I usually do not use dust covers with them.

 And remember:

My preservation procedures described here have been used by me personally; however, I will not be responsible for damage to your collection should damage result from the use of these procedures.

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