tube, pan & liquid watercolors

Commercial watercolor paints come in two forms: as a thick liquid or paste packaged in metal tubes, and as a dry cake in small plastic pans.

There's more to the two types of packaging than a difference in price. This page presents the main points of usage and care with each type of paint.

I should mention that you can buy dry pigment powder and prepare your own paints. Pigment, gum arabic and other ingredients are available commercially — packaged as expensive small jars from the major paint manufacturers (and available from most online art retailers), or packaged and sold more economically in bulk from companies such as Kremer Pigments that deal in artists' pigments primarily. Ingredient lists and mixing instructions can be found in the Gottsegen painting handbook and other sources. Just place a golf ball sized pile of raw pigment on a sheet of glass, pour dissolved gum arabic, simple syrup (sucrose syrup) and water into the middle, then knead the paste with a spackling knife for ... oh, about two hours. This is a labor intensive pastime, but I know one artist who swears by the result.

a brief history of watercolors

During the 17th and 18th centuries, watercolorists fabricated their own pigments and paints, using chemicals, earths or plant raw materials purchased from apothecary or herbalist shops. Recipes and mixing instructions were published in drawing handbooks, and these show that making paints could be complex and tedious work. Painters stockpiled finished batches of pigment powders, and mixed a fat pinch of the dry pigment with gum arabic, granulated sugar and water before starting a new painting.

In London, however, a few colourmen such as Robert Keating and Matthew Darly began to serve the artists' market around the middle of the 18th century, and by 1780 several were advertising their wares in London publications. In addition to papers, paintboxes and "pencils" (the term for watercolor brushes until around 1850), all sold premade dried pigments in tied off pouches of pig's bladder "about the bigness of walnuts."

Around this time, too, the firm of William & Thomas Reeves developed hard, dry cakes of premixed color, stamped with the colourmen's names and wrapped in paper. These cakes were dissolved into paint by rubbing them in a spoonful of water placed on special, 3" china saucers or mussel shells (the cakes were too hard to soften with a brush). The cakes and saucers continued in use until late in the 19th century, and "rubbing out one's colors" was the morning chore of many Victorian watercolor painters.

As topographical watercolorists began to travel England and the continent expressly to sketch landscapes and ruins, a variety of portable paint boxes or paint chests — typically made of mahogany, but sometimes of fine materials such as ivory or Wedgewood jasperware — also came into use. By 1800 these boxes were made with square recesses to hold hard paint cakes; by 1830 enameled tin boxes were also available. These metal boxes proved immensely popular: a one shilling box was invented in 1853, and by 1870 over 11 million had been sold.

In 1832, the new firm of Winsor & Newton began selling a semimoist paint formulation, based on a honey and glycerin vehicle recipe invented in France. The paints were prepackaged in tiny porcelain pans designed to fit the hard cake slots in existing paint boxes. Wrapped in foil to keep the paints moist, these greatly improved the convenience and portability of watercolors.

Finally, the collapsible metal tube with a screw cap for packaging mixed paint was invented in 1841 (for oil paints) by the American portrait painter John Rand. This was first adopted for watercolors by Winsor & Newton in 1846, using a modification of the moist pan paint recipe. These tubes replaced less satisfactory packaging concepts, such as the syringelike glass or metal tubes invented by the English artist James Hams in 1822. 

tube vs. pan

Tube paints are efficient for mixing up large quantities of paint (for washes, large glazes, or just a really big painting). They are ready for mixing straight from the tube and dissolve quickly in water.

Some artists claim that tube paints have a more vibrant color than pan paints, but I have not found that to be true — even when I measure the color difference digitally. I suspect difference may simply be due to the fact that it is easier to achieve a high concentration of paint and water with tube paints. Indeed, some artists use the paint straight from the tube.

The disadvantages are that it's hard to judge exactly how much paint you need for any painting, so you usually end up with excess paint on your palette, which dries out anyway. And once tube paints are contaminated with other colors (particularly one of the phthalos), they are difficult to retrieve.

Tubes are not a perfect packaging solution. Pigment and vehicle separate if the tube is infrequently used or has spent a long time hanging in the retailer's paint rack. The cap sticks if it is gummed up with paint. The tube can burst or the paint can dry out from prolonged exposure to heat or improper sealing. And tubes are bulky — they contain mostly water and gum arabic, and only 5% to 50% actual pigment.

Dry pan colors have different advantages. They are quick to set up and paint with — just open your paint box and wet the cake — and very easy to clean up. If protected from moisture and extreme temperatures, they will store indefinitely. There is no wasted color, other than what you lose in your rinsing tubs or leave in your mixing areas. They are easy to clean if you pollute them with another color (villain phthalo again). And they are marvellously compact and easy to transport.

The disadvantages of pan colors are that they require more fussing to moisten and mix up. They yield small quantities of color at first (though more when thoroughly moistened). Some pigments (such as earth pigments, viridian or rose madder genuine) form hard cakes that are more difficult to work with, and sometimes produce streaky color mixtures. The frequent rubbing of the cake required to moisten it or pick up paint can be hard on brushes, especially with the abrasive cobalt pigments. And pans are expensive for the amount of pigment they contain — anywhere from three to five times the cost of tube paints.

Don't make the mistake of thinking that tube paints are for "real" artists and pans are for students or children. David Cox, Winslow Homer, J.S. Sargent, John Marin, Edward Hopper and Philip Pearlstein, to name a few, are among the many artists who preferred pan colors to tube paints, even in the studio.

when to use

As you might guess, these relative strengths and weaknesses make the two forms of color more appropriate for different applications.


a brief history of watercolors

tube vs. pan

when to use

paint tube tricks

dry pan tricks

liquid watercolors

Pan colors are especially convenient for field work or small studio sketches. The folding dry pan palettes are light and compact, and the pans transport well — they dry out in a matter of minutes once the painting is finished, so they don't run together as you jostle your paint kit back down the mountain.

If the pan paints are well made, they will soften quickly and with little water. (Pans are usually harder to get started the first few times they are used.)

Dry pans are ideal for planning the palette for a painting. Experiment with paint combinations using the dry pans, and when you have the palette selection you want, squeeze out the painting colors from tubes.

Pans are easy to switch in and out of your dry pan palettes, so you can always pack in exactly the colors you want to render a particular type of geography or atmosphere. (I keep assorted extra pans in my plein air paint kit in an empty Altoids mint tin.)

Pan colors are fine to use for any small to medium sized painting, particularly when a large number of pigments are required in small quantities (for example, some botanical paintings) and large washes aren't required (botanical paintings again). I haven't seen any evidence that tube colors consistently look brighter or better than pan colors on the paper, since the pigments are identical in either form.

Many painters get along just fine doing field paintings with tube colors; they carry the small size tubes (available from most brands except Daniel Smith and M. Graham) and squeeze them out into folding field palettes, which come in a variety of designs and sizes.

A compromise approach is to squeeze out a quantity of tube colors in the studio onto a folding plastic or metal palette (or a flat palette with a snap on cover), and let the paints harden in the wells before transport to the field. Then they can be moistened on site and used in the normal way, though they can take longer to dry out once the painting is completed.

For medium to large paintings, or mixing washes or glazes, tubes are definitely easier to use. The main trick is to judge how much color to squeeze out for each painting.

Some artists simply work with a fixed palette, squeeze out plenty of color to start, and leave what's left to dry once the painting is done. To begin a new painting, they squeeze out fresh color to get the colors moistened, or spritz the dried paint with fresh water. (Some actually let the paint dry out before they ever start working, since they prefer the consistency of paint dissolved from a hard start.) Since these painters continually work with the same color selection, they only soak and clean out the palette when the paints get muddied or moldy, or are mostly used up.

I don't work with tubes in that way. I squeeze out just enough paint for the requirements of each painting. I wet all the paints with a small amount of water, then dilute down and mix these thick solutions for color mixing. I find this uses less water in the long run, and lets me work more quickly once the painting is started. Usually there is little unused paint when I'm finished, so I discard what's left and clean the palette rather than save the paint for another session.

If I haven't finished, I cover the palette to keep the paints for another day. All brands of tube paints rewet to their original brilliance after they have completely dried. It's better to let them dry than to try to keep them wet, since a puddle of wet paint will develop mold in a few days, and you'll have to clean up and start all over.

paint tube tricks

Tubes have some unique problems that you will encounter sooner or later. Here's how to deal with them.

Stuck caps. The common advice for stuck caps is to heat the cap and twist it off; some artists suggest using a match or candle. That's the wrong method!

There are different types of plastic used to make paint tube caps. A hard plastic such as styrene is brittle if stressed. This cap is dimensionally stable under heat, but can catch fire if heated with an open flame. A softer plastic such as polystyrene typically has a slightly waxy or slippery texture, and feels flexible or rubbery when stressed (press the edge of the flat top of the cap with your thumb, and it will bend slightly).

The softer, flexible plastic can warp or shrink if exposed to excessive heat, even the heat of scalding tap water, but there is usually no need to heat them in the first place: their naturally greasy surface texture makes them stick rarely if at all. If they do stick, gentle twisting with your fingers is usually sufficient to loosen them.

The harder plastic caps will stick, but are more resistant to heat. However, the heating is best done with hot (scalding but not boiling) tap water run only over the cap and metal shoulder of the tube for about five to ten seconds. (My kitchen has one of those separate, squat hot water dispensers for cups of tea, and this water works perfectly.) Never immerse the cap or tube in boiling water. Absolutely do not use a flame of any kind. You won't achieve an interior heat that is any greater than you get with hot water, and the flame can melt, char or ignite the plastic.

After the cap is heated, let it cool for a few seconds, then wrap your index finger completely around the top circumference of the tube and completely grip the rest of the tube in your fist, with the cap barely exposed. (Holding the tube by the end or middle may cause it to twist under the strain.) Gently unscrew the cap with the other hand, increasing pressure slowly and steadily. Great force, or tools such as pliers, should not be used. If the cap resists, heat again, if necessary for a longer time.

After the cap is unstuck, let it soak in warm water for a few minutes, then thoroughly clean the inside of the cap and the threads on the tube mouth with running water and a paper towel before resealing the tube. This will minimize sticking in the future.

You can minimize sticking caps by squeezing paint more carefully. Hold the tube an inch or so above the palette, so that the mouth of the tube does not push into the fresh pile of paint you are squeezing out, and shear the excess paint cleanly off the mouth of the tube (with the edge of a paint well or the palette surface) before recapping.

A reader has also recommended the clever expedient of wrapping the threads of the metal tube with white teflon plumber's tape. Cut a 3 centimeter long segment of tape, then wrap it counterclockwise around the threads (in the direction that you unscrew the cap) and trim off the excess with a razor blade. The tape provides a better seal, yet makes the cap easy to unscrew.

Nearly every stuck cap I have encountered has been on a tube of Winsor & Newton paint. These use the hard styrene caps with an unpolished, porous aluminum tube mouth that seems eager to stick with many kinds of paints. Most other brands use the softer plastic that rarely if ever sticks.

Final hint: when you throw a tube of paint away, unscrew and save the cap (soak and clean it first). Caps that must be repeatedly unstuck are likely eventually to be damaged, and it's handy to have a few replacements on hand when that happens.

Paint remaining in a nearly empty tube. The solution is a paint tube wringer available from most art retailers. The tube wringer is made of a pair of serrated rollers mounted in a pair of hinged plastic or metal handles. The handles are used to pinch the rollers across a tube of paint, then the rollers are turned with a knob to squeeze paint up the tube. It's very effective!

When the paint tube is nearly empty, a small amount of paint will remain under the metal top of the tube where a paint wringer can't reach it. You can use a pair of pliers to pinch the sides of the tube against the metal top, to force out the last bit of paint. I just bend the empty tube to one side, lay the tube on a table with the nozzle pointing straight up, and press down on the shoulders of the tube with my thumbs: the paint pops out the top.

Hardened paint. Certain types of pigments (especially cobalts) tend to harden in the tube.

Paint hardens because (a) the cap was not screwed on tightly, (b) the paint was stored near excessive heat — over a radiator or in direct sunlight, (c) the pigment was insufficiently "aged" in the vehicle when the paint was manufactured, or (d) the paint is several years old, including both the amount of time you owned it and the time it hung by its neck in a retailer display rack.

If the tube of paint is new or nearly so, request a refund or exchange from the retailer. If you want to salvage a hardened tube, you can do so in two ways.

The first remedy is to force a clear plastic cocktail straw (the narrow kind) into the paint through the mouth of the tube. Push the straw straight into the tube as far down as it will go. Pull the straw out. It should pull with it a plug of hardened paint. If the paint is too hard for a straw to penetrate, you can use a large nail instead.

Fill the hole you've just made with water, and screw on the cap. Knead the tube to mix the water inside with paint, but do not use too much pressure. Set the tube aside for a few days, and repeat if necessary until the paint is sufficiently softened.

The second remedy is to cut the tube open and extract the paint. With a packing knife or sturdy scissors, amputate the empty tube at the crimp, and open the end. Do this carefully, as some parts of the paint may still be liquid. You now can scoop out the paint with a small palette knife (cut down each side of the tube to make this easier).

The hardened paint can be used in several ways. If the paint is still semimoist, the most convenient recourse is to pack the doughy paint into empty plastic dry pans, available from most direct order art retailers (Daniel Smith, Jerry's Artarama, or Cheap Joe's). Let the pans set for a day to dry, then use them in the normal way.

If the paint is so hard it crumbles or breaks when you try to cut it, you can save the dried paint in a small jar, or wrapped in aluminum foil, until you need it for a painting. Dissolve the quantity of paint you need in water. (Usually the paint has to soak for at least day to soften thoroughly, and you may have to add gum arabic or glycerin to adjust the texture.) My preference is just to throw it away.

If the problem recurs, try buying the paint in smaller tube sizes — and use it as soon as possible. Better yet, switch paint brands or art retailer. Well formulated and manufactured paint, displayed and sold by a well managed retailer, stored properly and used within a few years by the artist, will simply not harden in the tube. Period.

Excess paint. If you squeeze too much paint out of a tube, or find that paint keeps flowing out of a tube after you have stopped squeezing it, just hold the tube vertically (with the mouth pointing upwards), and find a place where the tube has an oval diameter. Gently squeeze the oval of the tube at its widest diameter, between your thumb and index finger. This will change the oval to a circle, increasing the inside area of the tube, which makes room for the paint. The excess will withdraw into the tube.

dry pan tricks

Pan paints have many fewer problems than tube paints, but there are still a few tricks to know.

Empty pans. Pans are awkward to use when the color is nearly depleted. When you see white plastic at the bottom of the pan, it's time to fix it. Dampen the mostly used cake, then scrape out the residue paint into a wetted, half used pan of the same color, and pack it down with a palette knife. (Rinse and save the empty pan; you can refill it with tube colors.)

I don't recommend you simply top off the half used cake with new paint from a tube. After a while you end up with a residue of very old paint at the bottom of several layers of new paint.

Uneven paint. A common annoyance is uneven pickup of the paint, which soon results in a deep hole at the center of the cake. This happens especially quickly for softer colors, such as cadmiums, ultramarine blue, burnt sienna, or the phthalos.

The hole is created by your tendency to pick up paint from the center of the cake, as a way of preventing paint from dripping over the sides of the pan. The solution is to let the hole develop until it traps the paint solution, then to work the brush against the sides of the hole to widen it toward the edges of the pan. Once you've reached the edges, it's easy to work the cake evenly all the way to the bottom.

Filling new pans. You may want to use unique paints offered by companies that do not offer dry pans, or do not offer pan paints in whole pans (the size I prefer). You may also want to use tube paints to make pans as a way to save money; one 15ml tube of paint easily makes four whole pans.

The solution is to squeeze your preferred paint into an empty plastic pan. These empty pans can be ordered from most online retailers. If you don't find the pans in the catalog (usually listed under pan paint sets, or painting accessories), call them on the phone and ask.

You cannot prepare dry pans from Sennelier paints, or with Blockx paints in tubes with the black caps. These all use substantial amounts of honey in the vehicle, which prevents the paint from drying to a solid cake. Most other brands, including the newer formulations of M. Graham, dry out just fine. However, with some brands, such as Blockx in the white caps or Rowney Artists, the problem is just the opposite: the paints dry to a resinous brick that is very difficult to wet and lift with a brush.

Squeeze a small daub of paint into each bottom corner of the pan, so that you don't trap air in the corners or sides (this can cause the pan to loosen as it dries or trap water when you wet it). Next fill the sides and center of the pan, then fill to slightly overflowing. Use a palette knife to lightly shape the surface if necessary. Then hold the pan firmly between the thumb and index finger, paint up, and firmly tap it at the corner of a table or shelf three or four times, to settle the paint into the pan.

Let the pan dry for a day or two, until the surface is completely dry and the paint is firm but not hard to pressure. Most brands of paint will shrink to create a large dimple in the center of the pan. Fill this and let dry a second time, and repeat again if necessary. The pan is now ready to use.

Cleaning your kit. I am always surprised at the number of artists who work with a filthy watercolor pan box — muddied and contaminated colors, grungy mixing pans, pan holders clogged with dirt or debris. I can't tell if this is laziness, or an interest in appearing "artistic."

Every month or so I lift the dry pan tray out of my paint kit and completely rinse out and wipe clean the mixing areas, then completely wipe clean the pan holders and enamel base. Sometimes it's necessary to dismount the pans so they can be cleaned separately, and to remove dirt or sand trapped underneath.

Use a small (#6), damp sable brush to clean the surface of contaminated paints. Dismount the paint pan from the clasp tray, then use the brush to wet the paint lightly and lift foreign color from the surface of the paint. Wipe the sides of the pan, and reinsert into the tray.

Enamel paint boxes, and dry pan paints, are expensive. Regular cleaning will reduce trapped moisture or corrosives that will damage the enameled surfaces and exposed hinges and clasps; and crisp, clean pan colors are more potent and easier to use.

liquid watercolors

The newest packaging idea is liquid watercolors — pigment and vehicle prediluted in distilled water. This is a category with significant differences among products.

In a class of its own are the Robert Doak & Associates Artist Water Color, manufactured in small batches by Robert Doak in Brooklyn, NY. These are pure watercolor pigments, packaged in a variety of containers depending on the size of the order. (My preference, the 10ml. Size, comes in small, slender plastic squeeze bottles with a capped dropper spout that must be cut to open, like most brands of household glue.)

Packaged in squat stopper bottles, like those used for inks, are a few brands of mass produced "watercolors." The most popular brand is Dr. Ph. Martin's, which markets both a "Radiant Concentrated Water Color" (really a dye) and "Hydrus Fine Art Watercolors."

The "radiant" watercolors are not true watercolors (that is, pigment suspensions) but moderately diluted, "synchromatic transparent aniline dyes". Many of the colors are especially brilliant — and equally fugitive. As dyes, they stain the paper immediately and cannot be revised; they also tend to make surprisingly dull color mixtures (try mixing the bright blue and bright yellow, for example) because they do not reflect light the same as ordinary watercolors. They are used to stain leather, cloth and paper, and can be used for graphical art applications intended for photographic reproduction or printing (although these limited color systems are unlikely to capture the brilliance of many of the pure colors.)

As art materials these are pleasurable enough for kids and are convenient to use for conceptual sketches where the accent is on bright unmixed hues. Otherwise, they are unsuitable for any artwork you intend to last for more than a few months.

The "Hydrus" brand are standard watercolor pigments and vehicle in the same stoppered bottle format, with a significant amount of fungicide added to prevent the growth of mold. The major problems with these colors are the quality of the pigments and their appearance on the page, which to my eye seems rather dull. As the paints are already in solution, they cannot be used for drybrush techniques or masstone application. The bottled colors are easier to handle than tubes or pans, and let the painter get straight to work.

There is incidentally little or no lightfastness information provided with these products. With nonstandard color names such as "tangerine," "persimmon," "artic rose" or "slate blue," you have no way of knowing what pigment has been used in the mixture.

If you use these products in art works intended to last then you are only looking for disappointment.

a plastic paint tube wringer