Karen Sioson Watercolors: troubleshooting discoloration of paper

Wednesday, July 6, 2011

Troubleshooting Paper Problems: When The Sizing Goes Bad.

Was rummaging through my old stuff and saw this discarded painting. Perfect illustration for explaining stale sizing.

I have this habit of setting aside half-finished paintings when I get that feeling that something about it is off. "Aha!" moments sometimes come when you've stopped obsessing over something. Sometimes it would take me days or weeks before I would get back to a particular painting. This one somehow worked its way to the bottom of my pile and I forgot all about it. Almost a year has passed since I last touched it. When I tried working on it again to finish it, spots started appearing wherever I wet the paper.

Reminded me of salt effects. This one however, is caused by sizing gone bad. We have touched a bit on sizing in a previous post. (Watercolor Papers and Sizing). But basically, the idea behind sizing or the addition of gelatin to watercolor paper during its production is to make the paper more workable with watercolor. Sizing allows you better control over your watercolor as it decreases the tendency of the paper to absorb liquids and paints like tissue paper. Between the paper pulp and the gelatin, the gelatin would be the first to go stale with old stock paper. Signs of this would be the appearance of spots that don't go away after a wash or after an application dries. Another would be when you discover areas that resist any application of paint you put down on it.

There are several ways to hasten the deterioration of the sizing. As demonstrated in this ruined painting, one way is by wetting a painted watercolor that has lain undisturbed for months. You can also hasten the deterioration of new paper using the same principle. The moment you wet a watercolor paper, its sizing gets disturbed. Maybe water acts as a catalyst. This is the reason why you are advised not to stretch paper in big batches. Stretch only what you think you will be able to use within 2 or 3 months. That's just my estimate. In our weather where heat can be more than the usual, it is always more prudent to stretch only what you think you will use. The window of usability may be different in your environment and you should let experience guide you.

A sign that this was not bad paper to begin with is how the undisturbed, previously painted part is free of spots. Check the picture. You wouldn't know that the paper's sizing has gone bad if you do not re-wet the paper. When you find yourself itching to touch up a painting years after it is finished, remember what happened here.

Not all old stock paper go bad. I use Arches cold pressed watercolor paper in rolls. One of the most economical way of buying paper is by buying it in rolls. Because you cut to size, you minimize wastage of excess paper. As long as you do not get the roll wet and observe proper storage, the paper stays usable for years. Proper storage includes storing it in its original wrapping and in the box it came in and with the crumpled paper fillers still inside. Do not put this container/box in an area prone to dampness such as near windows, bathrooms, basements. Also keep it away from direct heat or sun exposure so the paper inside does not get heat-baked.

You do need to recognize what stale sizing on paper looks like, specially when you like to take advantage of art supplies on sale. Some stores put their older stocks on sale just to move the items and to make way for newer supplies. Some of these discounted paper will still be good for use but many might have sustained handling or storing damage. For this reason I prefer to spend on paper and get new stocks. You're not really saving on money if you get bad paper. But sometimes good bargains are hard to resist so if you must, at least learn to discern the appearance of stale sizing to help you shop wiser.

I wonder if you can see the very pale yellow spots. That is how spoiled sizing looks on paper that has never gotten wet. Just turned bad over time. (I keep samples of everything.) But don't go hunting for spots where there are none. Even new paper looks a bit uneven because of how the lighting plays off against the hills and valleys of the paper. The surest way to check is to wet the paper.

This is the same paper, now wet. Some new paper may have this tendency but on a very mild scale and if the paper dries without any marks, your paper is still good. For tips on how to minimize this tendency, check out my previous article Watercolor Papers and Sizing

There are times when you would come upon a defective batch of paper. The best way is to contact the seller and if no action there, the manufacturer to see if you can get a replacement. Might be wise for you to do a little sleuthing online to see if other buyers have been complaining about certain batches. You will have a stronger claim if your paper is from the same batch. But do not be too quick to blame the suppliers. Sometimes we may be unaware that we are doing something that harms the paper.

You can artificially ruin the sizing of the paper by soaking it too long under water. Prolonged immersion may be the culprit why some sizing coagulate in spots. This used to happen to me when I was a beginner. Thinking more is always better, I would leave watercolor paper soaking for as long as 20 or 30 minutes before stretching it. The suggested submerging time is only a few minutes. Only long enough for the paper fibers to get wet. If you soak it too long, even before you staple it down, you can tell you've ruined the sizing by the appearance of slightly darker spots on your paper like in the sample above.

Also, not all paper that develop slight spotting when wet are damaged paper. Even new and undamaged paper may develop these slightly darker spot discoloration when wet. But these would tend to disappear as the paper dries. If you can't tell any spotting on the dried, stretched paper, your paper is good to paint on.

That's it. Thank you for reading.

Monday, March 14, 2011

Watercolor Woes. Troubleshooting Paper Discoloration

Ever find yourself wondering why your watercolor painting done a year or so ago has started yellowing or browning despite you making sure you used acid-free paper? Chances are, you may be unknowingly doing something that is putting your art at risk for early deterioration.

Acidity is only one factor among many that may cause early damage to your painting. But if you can eliminate acidity as a potential problem, it will be a big contribution to the long term preservation of your painting. What exactly does acid do? Acid can cause premature breakdown of materials in paper, canvas and wood. It may also degrade your pigments, specially the paints that contain elements of metal in them.

When you buy your acid-free watercolor paper from the manufacturers and suppliers, it is as they claim, in a state of being free of acid. The paper has been processed so that naturally occurring acids and acids used in the processing of the paper pulp are neutralized and thus made harmless. However, this claim is not a guarantee that the paper will be immune from whatever treatment you are bound to subject it to. The responsibility of keeping your watercolor paper acid free is yours, once you get your hands on the paper.

How do you get acid on your paper? By getting chemicals on it that change the pH of your paper and by putting it into direct contact with materials that may leech acid.

Some advice the use of distilled water for your watercolors, for just this reason. A bit extreme and expensive. I, myself, only use the distilled water for the water mister I use to wet my palette (distilled water prevents the water in the bottle from getting mossy). But the use of distilled water for wetting may be the best solution for those who get their water from untested sources. E.g. Some ground pumps produce discolored and metallic hinting water which could not only stain your paper but also might turn out to be acidic.

Another source is the use of bleach to whiten or erase a mistake. You may even read of instances where people (most likely students and not professional artists) immerse whole papers in it to bleach out color on an already used watercolor paper. Technically speaking, most bleaches are strong bases (very high pH). But strong bases have the same degrading qualities as acids. You are still messing with the pH of your paper.

One popular technique for achieving beautiful textures in watercolors uses salt. I've seen wonderful works of artists using this technique. Done right, you will not even be aware, salt has been used. I'm tempted to try it myself but the use of it is quite controversial so I'm holding out. Lately it has been claimed that salt is actually acidic or causes the paper to be acidic. Who would have thought, eh? But as that is still under contention, it probably is best that we wait for the official findings before we put a final verdict on its use. Meanwhile, I'm experimenting on safer alternatives. If ever I turn out a closely similar effect using very neutral materials, I will share on the blog.

The most common cause of getting acid on your paper though is by the use of unprotected wooden boards for stretching. Most beginners do not realize that the reason wooden boards sold in art workshops and art stores are expensive is because these have undergone more labor intensive treatment than your regular boards. These stretcher boards have been sanded, primed and sealed several times to make the surface as non-porous as possible. These are made to withstand getting wet paper on them. Students and beginners often improvise on a lot of things in an effort to save money and the drafting board is often used as a replacement stretcher board. They surmise, both boards look similar anyway. But most drafting boards are just something a little better than bare plywood. Most often, their manufacturers only sand the surface to give the students a smooth surface to do their drafting on. They were not intended to get wet. Now what does unprepared wooden boards have to do with acidity? Just this. Even with oven dried / sun dried wooden boards, the moment you wet the wood fibers (as what would happen when the wet paper gets in contact with the dry board), you start reconstituting the dried acid in the wood with water. Think tea. As your paper dries, it would pull the now acidic water from the wood onto the back of your watercolor paper. The damage can sometimes be readily obvious and you're lucky if you spot this right away. It would save you the effort of painting on damaged paper. But sometimes, the damage may become apparent only after weeks, months, or years. By then, too late. More than the loss of paint and paper, I think I would be sorrier for the time invested in a painting that would get ruined earlier this way.

Protect your art, use a safe stretching board or use paper that require no stretching.

On my next post, I will upload a simple yet very affordable solution that would help make your untreated/unprotected wooden supports, waterproof. This is for fellow watercolorists, specially in my country, who have no access yet to gator boards. (The only way you can get gator board or similar here is through online stores abroad). I'm still employing this method to waterproof the support for my watercolor paintings, specially the ones that have unusual dimensions that do not fit on the gator boards that I have.

Here's a pic of a watercolor painting that I stretched on a home-made waterproof board (taken years ago). I like how you can go as big as you like. Even make a support the size of the whole plywood board 4 x 12 feet.