A truck bed liner is a waterproof covering designed to protect the interior of your truck bed from water damage. If you have a pickup, you need one. Why? Because a pickup is at the mercy of nature. It is prone to all kinds of weather - it can rain, snow, sleet or hail, and the bed can quickly become an underwater pile of wet fluff if things get a little wet.
Waterproof truck liners are an excellent way to deal with these problems. They also prolong the life of your truck by keeping water away from all sensitive parts, such as the brakes, transmission, alternator, etc. - which means fewer repairs and a better chance of fewer headaches for the owner. The spray itself acts as an antifreeze, keeping water away from the vulnerable parts of your truck, but what if the spray doesn't stop cold weather? What then?
In most cases, hard plastic liners will do the trick. These materials are very sturdy and relatively inexpensive, so they are affordable even in a time of need. There are several types of truck bed liner sprays to choose from, so it is important to understand which material waste you have to deal with in your particular case.
The type of truck bed liner you use will depend on what you are trying to prevent. If you need something to prevent slush, you can use polyisoprene. This material is thick enough that it freezes up and solidifies when it thaws, so any water that gets into the bed will freeze right away. Most liners today also feature an external reinforcing layer, which is connected to the inside of the material, giving extra strength and a leak-proof seal.
On the other hand, if you need something to prevent moisture from seeping up through the material, you should go with two Component sprayers. These liners work by spraying both sides with a coating that becomes harder as it dries, preventing water from reaching the bed. They are much thicker than traditional hard plastic liners, and as such require two coats. Two-Component liners may be more expensive than traditional liners, but they are more effective and cost less.
Finally, for effective, permanent bed liner protection, you have polyurethane. Polyurethane is stronger than the liners mentioned above and has no external reinforcing layer, so it forms a more rigid outer shell around the bed. Although it can be sprayed in various directions, there is a limited amount of control over how it will penetrate. It is generally more effective if shot on with a fine-tipped paintball marker. Other options include foam and fiberglass, although these are not nearly as effective.
If your liner needs are very specific, or if you are interested in customizing the spray pattern, there are custom sprayers available. Rhino Opti-spray is made by Impression Paint Company and has excellent reviews. It is similar to the liners discussed above, but uses concentrated foam to fill in small cracks and spaces. It requires an air compressor and a compressor hose, and it produces great-looking results. It is also relatively inexpensive, which makes it a good choice for a new truck bed.
In summary, choose your coating depending on whether you want a water and heat-resistant coating, or one that can be sprayed with a paintbrush or a small hand-held spray gun. If you are planning to paint the truck beds in more than one color, you should look into a two Component sprayer, which coats the bed twice with two coats of foam. There are sprayers for acrylic paints as well, and polyurethane, but these are less common and therefore more expensive. Finally, remember that the quality of your liner will directly affect the life of your sprayer, so choose wisely!