Compared to other paints, watercolors are very convenient for travelers. Dry watercolors are an obvious choice for the sake of simplicity, but even liquid watercolors can easily be carried on airplanes. However, there are a few TSA regulations and other practical considerations to keep in mind when packing watercolors.
Dry watercolor sets are small, convenient, easy to pack and completely unrestricted on airplanes. If you're picking out paints specifically for travel, they're an obvious choice. However, liquid watercolors are also relatively easy to carry. Because they are not flammable, they may be carried in checked bags or carry-ons.
If liquid watercolors are packed in a carry-on, they are subject to TSA's liquid and gel restrictions. Each tube of paint must be less than 3.4 ounces, and all tubes must be packed in one clear, zip-top plastic bag along with any other liquids and gels you are carrying on board.
Although they are permitted, liquid watercolors may show up in security scans, especially if they are in metal tubes. Bags containing watercolors are relatively likely to require extra inspections. Facilitate this process by packing them in an accessible way, for example, in their own bag or compartment or as the top layer of a suitcase. Checked bags should not be locked, in case the contents need to be inspected.
Sealed containers are under extra pressure during air travel, especially in checked bags. Paint tubes usually travel well, but it is possible for them to burst due to this pressure or to rough handling. It's best to pack liquid paints in a plastic bag inside your luggage. A clear plastic bag is also convenient in case of security checks.
Other Tools and Materials
Though watercolor paints are relatively easy to carry, related items may be subject to more restrictions. Any sharp or pointed palette knives must be packed in checked bags. Flammable liquids, such as varnish, may not be carried on airplanes at all.
Finished paintings, paper and other painting surfaces are unrestricted, but may be difficult to pack securely. Packing them in a portfolio and carrying it on board, if possible, is usually the best option.