| Author | Message | ||
  Terry Intermediate Member Username: Terry Post Number: 51 Registered: 8-2006 |
Another test | ||
Terry Member Username: Terry Post Number: 50 Registered: 8-2006 |
This is a test to see if the new anti-spam software works. | ||
Kisha Unregistered guest |
The statement that NaCl plus H2O is true in a gross sense, but it is much more complex than that. Even though the net effect is for all of the ions to balance out, at any given instant the ions are releasing and rejoining causing instantaneous moments of acidity and alkalinity (Ph ) imbalances. Thus at any instant there are free H ions, free OH ions plus free sodium and oxygen atoms all ready to combine with anything out there that will receive them. For this reason salt water is **highly corrosive.** (I would explain how that happens in more detail if you wish but really this is getting off topic). The fact is museums know salt water acidifies paper. | ||
Ano Neimus Unregistered guest |
Well, if there is anybody who would know the procurement practices of every museum in the world, I suppose it would be good ol' Tom. | ||
Garydoc Intermediate Member Username: Garydoc Post Number: 58 Registered: 8-2006 |
Also, acid is the p[excess] of [H+] over [OH-] which can't happen if you disolve NaCl in H2O. [H+]/[OH-]=pH Gary | ||
Garydoc Intermediate Member Username: Garydoc Post Number: 57 Registered: 8-2006 |
Kisha, NaCl + H2O always makes salt water. The reaction is HCl +NaOH => H2O*NaCl (salt water). It can't go the other way without the input of energy as in electrolysis where the [Na+] (sodium ion) goes to (-) terminal and the [Cl-] (chlorine ion) goes to the (+) terminal. Any issues of archivability can't depend on changing the pH by the use of the salt. If there is an archival question about the use of salt, this aint the answer. Gary | ||
Whitewatercolor Intermediate Member Username: Whitewatercolor Post Number: 75 Registered: 10-2006 |
Thanks for a chuckle on this really dreary, cold day. | ||
Bill Unregistered guest |
Whitewatercolor H2O-- Here's another appropos quote,"Some people would argue with the sun for coming up." | ||
Whitewatercolor Intermediate Member Username: Whitewatercolor Post Number: 72 Registered: 10-2006 |
I read a quote somewhere, that I can't seem to relocate--I thought it was this site, but maybe not. It was something to the effect that if you think I am doing well with watercolor it is because I am standing on the shoulders of giants. Meaning I have taken the advice of those who have come before me. The fact that Tom Lynch told me that salt is not archival and that museums won't purchase work in which salt has been used is good enough for me. Before I started reading about some of the great artists of the past on this site, it was my contention that I could shortcut my learning by gaining my knowledge from the people who studied under the greats and then condensed the information to pass on. But thanks to the influence of some here--I just ordered a couple of Whitney's books and one of Stabins. You guys have me convinced to dig deeper. | ||
Kisha Unregistered guest |
I was just clarifying the probable chemistry because some expressed rather confused opinions on the matter. I would certainly assume that the pinpoint spots of paper beneath the salt would eventually turn dark brown. In terms of thought about the chemistry getting in the way of creativity--thoughts about anything other than painting get in the way. This discussing groups gets in the way of painting. Your reading my words at this moment gets in the way of your painting. There is no more pertinent information for the artist than the chemistry of his materials. Whether he cares is another story. | ||
Eugene Advanced Member Username: Eugene Post Number: 110 Registered: 8-2006 |
I think all the concerns about chemistry and archival quality, sometimes get in the way of creativity. I doubt very much that Sargent, Homer, or any of the great pioneers of watercolor worried very much about how long their work would last. My work isn’t comparable to theirs and if it last as long as I do, I’ll be happy. | ||
Marie Advanced Member Username: Marie Post Number: 129 Registered: 8-2006 |
Thanks, Kisha and Jay. That helps a lot. I couldn't find anything on the web that explained it one way or the other. No salt for me in painting. By the way, used a toothbrush to add texture to a painting last week, and I was happy with the results. | ||
Terry Member Username: Terry Post Number: 49 Registered: 8-2006 |
Fixed | ||
Kisha Unregistered guest |
TERRY--The website Rekha posts are not in hypertext. | ||
Kisha Unregistered guest |
water produces NcCL --er NaOH-- sorry--quick typing in the early AM while grandchild is calling me was to blame-- | ||
Kisha Unregistered guest |
Rekha--To my knowledge I have never heard about this one way or the other until it was brought up in this thread. I tried a web search using all sorts of parameters and found nothing on it it. Jay--in following this discussing it seems to me that buffers in paper are used to neutralize the natural acidity inherent in paper, Buffers form a balance with the current acidity--to much of a buffer and the paper becomes alkaline. Thus, logically, there is enough buffer just to overcome the acidity present. If more acidity is added--and I would suspect that grains of salt mixed with water and producing free hydrogen ions in the hydrochloric acid would introduce thousands of times more concentrated acidity (in that one spot where the salt grain is) that the buffer can handle. Thus the PH drops far below 7 (neutral) and the net result is acidification. Of course this is speculation but it is based on logic and not at all on clumsy thinking (blithly ignoring?--give some credit). I've even taken into account the fact that salt also when mixed with water produces NcCL which would release OH (base--alkaline) ions to contradict the Hydrogen ions and reurn them to NaCl and H20. However , at any given moment hydrogen ions are present and the PH would effectively be lowered. Bottom line is, when one's art is at stake, I would err on the side of caution. Trusting a bit a Calcium carbonate buffer to protect against an onslaught of pure salt is like expecting a windbreaker to protect from a rain of bullets. When the painting is at stake, assume damage until safety is proven, don't assume safety until damage is proven. Kisha BS Chemistry, Columbia University | ||
Rekha Advanced Member Username: Rekha Post Number: 117 Registered: 8-2006 |
In any case, its use was first patented in 1994, so not much time has elapsed to make any comments http://www.freepatentsonline.com/5362518.html | ||
Rekha Advanced Member Username: Rekha Post Number: 116 Registered: 8-2006 |
Need say no more http://www.time.com/time/magazine/article/0,9171,825353,00.html | ||
Rekha Advanced Member Username: Rekha Post Number: 115 Registered: 8-2006 |
Who has the evidence that salt causes deterioration of paintings? In any case a lot of the pigments are extracted using salt. Why is it that those paintings don't show detioration? | ||
Jay Unregistered guest |
"De-acified paper is no longer de-acified if acid is put on it ..." ^^^^^^^^^^^^^^^^^^ But, is it? Again, what of the buffering, which you so blithely ignore? "Buffers are such chemicals as calcium or magnesium carbonate, which can absorb a significant amount of acid. Buffered papers are often slightly alkaline with a pH around 8.5. A pH moderately higher than 7 is not considered harmful in paper." (Src: The Chemistry Of Paper - http//trueart.info/paper_chemistry.htm) In addition, normal tap water is usually 'hard', or alkaline, which offers a bit of neutralization in itself. I don't suppose many bother with obtaining pH neutralized or even distilled water for their painting, so again the scales are generally tipped towards alkalinity. And this doesn't even embrace the properties of sizing, which nearly all watercolor papers have, and is yet another 'layer of protection' for the cellulose fibers the acid attacks. [Also see: www.handprint.com/HP/WCL/paper1.html] [& Google: "watercolor paper" +buffering ] There's considerable moisture in the air - water vapor. Sealing it would prevent further 'fuel' for the acidic process, which is itself neutralized as it works. So I can't see how you can justifiably say "it wouldn't matter at all." But you're probably a whole lot smarter than me, so.....you win. Pass the salt, please. /Jay | ||
Kisha Unregistered guest |
De-acified paper is no longer de-acified if acid is put on it (the HCl produced when salt meets water). Sealing it wouldn't matter at all. | ||
Jay Unregistered guest |
Archival quality paper is de-acified, and also buffered....so you need to figure what part that plays in it. Me, I wouldn't worry about it. If there were any great concern, there are numerous sealants available, plus prints made of the painting wouldn't suffer. My 2¢, /Jay | ||
Kisha Unregistered guest |
NaCl + H2O ---> HCl (hydrochloric acid) + NaOH (sodium hydroxide). It's about the acidity of the paper with salt added. It's not about the longevity of the salt but of the paper--plus the paint is probably chemically affected too. | ||
Raliegh Intermediate Member Username: Raliegh Post Number: 51 Registered: 8-2006 |
I know it's a preservative. | ||
Marie Advanced Member Username: Marie Post Number: 126 Registered: 8-2006 |
Picking up on some dicussion from a previous thread ... I have always wondered whether salt is archival in watercolor. My intuition tells me to be suspicious of salt in watercolor, but I don't know anything about chemistry. Can anyone explain in layman's terms why salt is or isn't archival? |
