An artist painting with watercolors
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What is the difference between watercolor paints that come in pans and those in tubes? How do you decide which is best for you? Here are some of the characteristics of each that will help you decide when to use one or the other.

What Are Watercolor Paints?

To make watercolor paints, the pigment is mixed with gum arabic and a small amount of glycerin for adhesion, flexibility, and a slightly glossy finish. This mixture is then put into metal tubes, where it has the consistency of toothpaste, or dried into a semi-moist solid form and cut into pans.

Pans

Pans are small square cakes of pigment cut into either full pan (20 x 30mm) or half pan (20 x 15mm) size. These are put in small plastic or metal boxes to keep the paint pans together as you use them. The boxes have a hinged lid to keep the pans in place when closed, and that, when open, also serves as a palette for mixing colors. 

Pan sets come in pre-determined colors, but you can also swap colors out and customize them for your own purposes or subject, creating different color palettes if desired. 

Pans can be hard to start when you first unwrap and use them, but after they are moistened and softened a bit it is easy to pick up the color. You can soften them initially by putting a drop of water on them and letting them sit for a minute.

To get paint from a pan, use a damp brush to pick up a little color, then put it on your palette (either the lid of the pan watercolor set or a separate, freestanding one). You can add more water to the color on the palette or mix it with other colors. You can also work directly from the pan, but you need to be careful not to contaminate it with other colors. 

Keeping your pan colors clean is one of the difficulties of working with pans. Unless you're very good about washing your brushes before getting a new color, a pan can become dirty or contaminated with other colors.

If you do get the pans dirty, and when you are all done painting, use a damp cloth or sponge to wipe them clean. Then let them dry a few hours before closing the box in order to keep the pans from sticking to the lid when you open the box the next time. Also, make sure to dry off the palette on the inside of the lid.

Tube Paints

Tube paints contain more glycerine binder than pans. This makes them soft and creamy and easier to mix with water. Tubes come in three sizes: 5ml, 15ml (the most common), and 20ml. Because you can squeeze out as much paint as you want, tubes are good if you want large areas of color. 

Tubes are relatively easy to keep clean, but make sure to wipe the thread of the tube clean with a rag before replacing the cap or it may stick and be difficult to open next time. It helps to hold the cap and metal shoulder of the tube under hot water for five to ten seconds to expand the cap and soften the paint if that happens. 

If you squeeze out more paint than you use and don't clean off your palette, you can still use the paint later since it remains water soluble and can be reactivated with water when dry. 

If you don't replace the cap of the tube right away, the paint in the tube will dry out and harden. As long as the paint is not too old, if this happens you can cut the tube lengthwise, accessing the paint and using it as a makeshift pan, reactivating the dried paint with water. 

If the paint in the tube has dried you can also force a hole through the mouth of the tube with a nail or end of a brush and add some water, then put the cap back on and knead the tube to mix in the water and reconstitute the paint. You can also cut the ends off of tubes (at the crimp) to access dried paint and reconstitute it by adding a little bit of water.

Pans vs. Tubes

Pans are easier to use because you have immediate access to the colors. You don't have to put your brush down, open a tube of paint, and squeeze a little color out. They are often preferred by painters for field sketches, visual journals, and plein air painting because of their compactness and portability. You may want to have both pans and small tubes of watercolor or gouache (opaque watercolor) in your art travel pack.

Pans are less expensive than tubes, but are small and are better suited to small studies and paintings. They are only suitable for small brushes.

Tubes give you flexibility as far as the quantity of paint you want to use, along with the size of the brush, area to be painted, and the size of the painting.

Tubes are easier on your brushes than pans as you don't have the temptation to scrub with your brush to pick up a color.

Ultimately, each has its own advantages. Try both and see which you prefer. It may well be a mixture of the two.

Tips

There is a huge difference in quality between student and professional watercolors. Rather buy a few quality paints than a large range of cheap colors. You will see the difference in coverage and color intensity once you compare the two different qualities of paint. 

There is also a difference in paints between manufacturers. Try different watercolors made by different manufacturers to see what you prefer. 

When you replace a pan, remove any bits of an old pan before putting in the new one, otherwise, it won't fit snuggly. Combine the old pan pieces with other old pan pieces of the same color in another pan.

Another very convenient option for replacing paint in a pan is to simply fill the pan with paint from a tube and let it dry. Sennelier paints don't work well for this since they tend not to dry out. Start by filling the corners and work around the edges toward the middle. Shape it with a palette knife and let it dry.