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Of all topics surrounding formliner, we are most often asked about designing with formliner. In this article series, we’ll cover a number of categories within the design aspect of formliner.

As you consider an aesthetic treatment for your construction project, you’ll likely consider formliner as a way of creating a distinctive look. Whether you’re trying to blend in with the natural surroundings or make your project stand out, concrete formliner (or form liner) is an excellent vehicle to achieve your goal.

In this first segment of our formliner series, we start by discussing the two main types of formliner material and how each material impacts the actual concrete finish and the cost of the job.

Urethane vs. Plastic
The majority of formliner is made from either urethane/urethane derivative or plastic. Though there are significant differences within the urethane family and within the plastic family, we’ll focus on the differences between the two materials. Generally speaking, the main differences between the materials are:
1. Texture and Finish
a. Realism and Depth of Relief
b. Deflection
2. Re-use Capability
3. Overall Project Cost

Texture and Finish
While both materials will create a textured surface, there are very distinct differences between a surface formed with plastic formliner and a surface formed with urethane formliner.The most obvious difference is in the finished appearance of the texture. Urethane formed walls have a depth of detail and a texture that is very similar real stone, whereas plastic textures tend to be muted and somewhat diffused, with a maximum relief of 1.75″. The reason behind this difference is primarily rooted in the properties of the raw material and the resulting production process. Urethane liners are created by applying liquid urethane to actual stone textures. As a result, the liquid forms to every contour and line of the stone texture. Plastic, on the other hand, is formed using a hard plastic sheet, heated so as to be pliable, and then vacu-formed to a textured mold. Only the most prominent and basic textures of the molds are picked up by the plastic. The level of realism can be vastly different between plastic and urethane. If your project requires nothing more than a basic texture, plastic may be the most cost-effective route, however, if aesthetics are important, urethane will provide you with the most realistic finish possible.
A second major difference between plastic and urethane is the seam or joint that occurs where two formliners meet. Plastic formliner is generally available only in rectangular sheets. The resulting joints end up in a very predictable pattern, and often require patching and other work to disguise or reduce the visibility of the seam. Urethane can be formed into keyed parts of different size, such that any seams appear only in the grout joints of the design.
The third major difference with regard to appearance is the tendency for plastic to create deflection on the concrete surface. Even with wood backing added on the job site, plastic is materially weaker than urethane and has a propensity to bulge and deform the surface of the finished concrete. Generally speaking, urethane does not suffer from thermo-expansion, nor is it as prone to deflecting under the stress of concrete. The higher the wall or pour, the more stress and weight is added to the formliner, and the tighter the liners need to fit together.Re-use Capability
Plastic and urethane differ when it comes to durability.Generally speaking, plastic formliner is less durable than urethane formliner. Because it is more brittle, plastic will fatigue with each strip and eventually break, often on the ends, or around the attachments to the forms.
Wood-backed urethane is much different. Because it is a solid material, there is a very minimal chance for the liner to fail at the ends, and as a flexible material, urethane has a gasket-like effect on all attachments (screws, bolts, etc), with the urethane actually enclosing the attachments.
Having noted this, however, there are different grades of urethane that offer a different amount of re-use, depending on the actual needs of the project. For a cast-in-place project with extensive angles and arches, the contractor will need to cut the formliner to fit the architectural demands of the project. Custom Rock can help you plan your fornliner usage such that waste is minimized. Our experienced salespeople can provide shop drawings showing the layout of the liners. Further, we’ll work with you to determine the most cost efficient way to use the liners.Overall Project Cost
In all areas of aesthetic difference, urethane is superior. Unfortunately, it is also more expensive per square foot of material. However, when evaluating the total cost of aesthetics for your project, you need to take into account the number of re-uses for the formliner. The cost per square foot of total concrete surface is the relevant metric. An implicit cost, sometimes not taken into account when choosing between plastic and urethane, is the labor to replace any liners that break or shatter, or the labor to repair any obvious seams. Often, urethane ends up as the overall less expensive alternative when accounting for these factors.

Custom Rock Formliner is the leader in stone texture formliners for poured-in-place, precast and tilt-up applications. Custom Rock also offers custom molding for architectural applications such as murals and graphics as well as a large variety of textures including, but not limited to, stone, brick, split-faced block, wood, fractured fin and sandblast. Visit us at: http://custom-rock.com/