View Full Version : Make-it-acid-free sprays

06-11-2014, 08:31 AM
Has anyone used those make-it-acid-free sprays? I have lots of old mat board cut-outs given to more by a framing shop and have no idea if they are acid free. I would like to experiment with various pastel grounds on these but want them to be acid free in case I produce a keeper.

06-11-2014, 10:58 AM
How about a quick dip in dilute baking soda solution?

Last week I sat with a bunch of different locally available papers (tracing paper, cartridge paper, craft paper etc... ) and some litmus paper. All except the cheapest ones turned out to be acid free (pH 7-8). The acidic ones cost less than about 10 cents per sheet (pH 5-6). Also the hardware store emery and sand paper were acidic (pH 6).

Interestingly, I found out that gum arabic is acidic (pH 5). That's how it's supposed to be.

Also, the definition of non acid free is 1 gm paper in 50 ml water. I tested with a tiny piece of paper and a couple of drops of water. So there's quite some leeway about how acidic a paper has to be to be damaged over time.

06-11-2014, 11:42 PM
Thank you, Indraneel. Your information is very interesting (especially that gum Arabic is acidic since it's the binder for watercolor paints). With so much emphasis on acid free materials, one would think that only the highest priced papers would meet that criteria. I'm afraid I don't understand your definition of acid free as "1 gm paper in 50 ml water." Does this mean you put a gram of paper into the 50 ml water then checked with litmus paper? And you think a quick dunk in baking soda water might work. I tend to agree. The dunk would probably penetrate the paper better than a spray, but perhaps spraying it on would also work. Thank you again, and I'm sorry I didn't reply sooner. I signed up for email alerts on this thread but didn't get one, so I didn't realize you had posted.

06-12-2014, 12:47 PM
I bought the spray years ago but am not sure how well it works. I used it on some pieces I did on cheaper paper and they didn't degrade, but it hasn't been so long that I'd know for sure. It's probably a lot better than not using it. I'd spray the back as well as front.

Also mat scrap from framers is often the better stuff. I used to get lots of it, since I work small most of it went into actual mats. They use archival mat board on most serious jobs so I got a lot of free good archival boards. Cool that there's a way to test it! The frame shops in New Orleans would put out huge boxes of it on the street for local artists to take whatever we found useful.

06-12-2014, 01:25 PM
Glad you found it useful, Blayne. The 1 gram paper in 50 ml water seems to be some kind of standard for paper testing. I read it on some conservation site, but forgot the link. I just cut a piece of paper about 1cmx1cm, soaked it in 2 drops of paper, mashed it with a stainless steel spoon, and checked with litmus paper. I used full scale litmus paper (pH 1 - 14), and it was not difficult to match the color changes.

The acid free probably is a result of using lime based fillers in most commercial papers. It would probably make sense to check the pH first for the mat board that you have. If it's already alkaline, it'll save a lot of trouble, including potential warping issues while spraying.

1 gram for 300gsm paper comes to a piece about 6x6 cm; which for 50ml/gram paper is about 1.5ml water per 1cmx1cm piece of 300 gsm paper.

06-12-2014, 04:19 PM
Robert, thanks for your input. I think I'll hold off buying any spray until I do some testing. And I may try spraying with a baking soda and water mix on both sides then retest any acidic papers. I really like to work on a firm support like mat board or foam core and put on my own pastel ground. My local framer told me she just tosses her mat scraps--such waste. Of course, we're not in New Orleans :( where there are street artists who would use it. Those must have been great times for you!

Indraneel, thank you for your detailed explanation, especially giving the paper sizes because I don't have a scale to measure grams (gee, how did I get through the hippie days without one?!) The testing procedure sounds very easy and I do have lots of 100ml droppers left over from visits to the vet with my cats. I knew those cats could be useful for something:)