Sunday, April 2, 2017

Do watercolors expire?

Do watercolor tubes and pans expire, and what to do about it? In my experience, the two most common ways that the paint in watercolor tubes or pans deteriorate are drying and separating. Paint may also mold or change texture.

What about other art supplies, such as watercolor brushes or paper? In this post, I will go over a few of the ways that art supplies may deteriorate and what to do about it.

Watercolor tubes and pans 

1. Drying

What is it? Watercolor paint dries out in watercolor tubes or cracks in pans.

Despite having some tubes that are getting on in age, this only rarely happens to me, and then usually with small 5 ml tubes that have been left unused for a while (read years!)

In pans, I have found that certain colors are more prone to drying, such as the Umbers, Prussians, and Viridian.

What to do? If only a little paint has dried out in the tube, I generally squeeze it out and keep going. If the problem is more widespread, prod a bit inside the tube with a straightened-out paper clip.

If paint in a pan has dried up into crumbles, I generally use paint straight out of a tube instead.

I also know that some artists, as a last resort, cut the tube open and reconstitute the paint with a drop of gum arabic or water, alternatively add a drop of distilled water and a drop of glycerin to the pan.

How to avoid? Keep the tubes tightly closed and store them in zip-lock bags if not used for a while. Use colors more prone to drying straight out of the tube instead of in pans.

Also, if you fill pans from tubes, only fill them halfway at first, let dry for a few days (can take a week depending on humidity!), and then fill them again to minimize cracking.

2. Separating

What is it? The watercolor separates into an oily part and a color part in the tube. The pigment and vehicle (usually gum arabic, the binder) are separating in the tube. When you squeeze the tube, only the oily part comes out – and it may be a lot of it as the pigment only constitutes 5%-50% of the volume (see Handprint).

This is unfortunately becoming much more common now than it used to be and happens to every few of my brand-new tubes as I open them up for the first time.

What to do? Sometimes I just squeeze the oily part out and keep going (but the paint risks drying up and you will get less paint left). You can also try to mix it back in with a straightened-out paper clip.

How to avoid? I don’t have any good advice here, but suspect it has more to do with manufacturing quality…

3. Texture change

What is it? The paint turns textured and “pebbly” instead of smooth inside the tube.

This has happened to me with black colors, earths, and sepia, for example, after having been stored for a while.

What to do? Toss it!

How to avoid? Don’t keep your watercolors for too long!

4. Mold

What is it? The mouth of the tube or the top of the pan turns moldy.

Strangely enough, this has only happened to two colors that I have used, Viridian (on repeated occasions, both pans and tube) and Winsor Green blue shade (once or twice).

What to do? I toss the tube or pan and often mix my own greens from blue and yellow!

How to avoid? Keep your tubes and pans dry, but in my case I really could not tell what brought it on…

5. Air bubbles in the tube

What is it? As you squeeze the tube, only air comes out, sometimes filling as much as half the tube or more!

This is, together with separation, another thing that is becoming more common now than it used to be, and it can be costly, as there is nothing you can do about it.

What to do? Squeeze the air bubble out and hope it isn't too big so you don't lose too much paint.

How to avoid? This is directly related to quality control in the manufacturing, so there is nothing the customer can do except let the manufacturer know this is an issue.

Watercolor paper

A few of the ways you can tell paper is aging are yellowing and stains becoming visible.

1. Yellowing

What is it? A wood-based paper turns yellow and brittle with time. (There are more factors at play than that, see link below for more.)

What to do? Toss it.

How to avoid? Buy 100% cotton, acid free paper. Use water that is not acidic(!) Also be aware of additives, such as whitening agents, that may affect the quality of the paper but that are not taken into account in the paper standards. See this post for more about archival papers.

2. Stains

What is it? With time, stains such as fingerprints due to the oils on the fingers of anyone who has handled the paper will become visible.

What to do? Cut off the stained part and use the rest, if not damaged, but be aware that more stains will show up with time...

How to avoid? Keep your hands dry and clean (no lotions, etc) or use cotton gloves, don’t touch the paper surface, purchase paper in larger, pre-packaged units instead of only a few at a time, check the paper already in the store.

3. Texture variation

What is it? Globs of sizing are visible as smooth areas on the paper surface. This is a manufacturing defect, hopefully more common with cheaper papers(?)

What to do? Cut away or toss.

How to avoid? Can’t really do much to avoid it, but avoid papers where this is a common occurrence. I check each paper prior to using it and only use the parts that have the correct grain.

Watercolor brushes

Brushes tend to lose their sharp point over time and hairs may fall off or break. The handle may also crack and the ferrule come loose.

1. Hairs that break off or fall off

How to prevent? Wet the brush tip prior to use to soften it, especially important with the fragile squirrel hairs, which easily break.

2. The wood handle and its painted surface cracks

How to prevent? Never let the brush stand in water and only let the water touch the brush hairs, not the shaft.

3. The brush point loses its sharpness

How to prevent? Treat especially sable brushes gently, don’t rough up dry paint in pans with the brush (use a nylon brush and a few drops of water for this purpose), clean the brush gently and reshape its tip with your fingers.

If you use rough papers, or brands with a rougher surface, your brushes may also wear out faster.

In short, to answer the question if watercolor paints, papers, and brushes expire with time, I would say that good quality art supplies can last a lifetime

However, it is hard to know beforehand just how a brush or tube will fare. It varies with quality, and quality varies not only with the brand but also with brands over time.

I have brushes that I bought many years ago that are still in good shape, as well as brushes that cracked within a year. Ditto paint tubes or pans or paper.

What is your experience?

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