Spectrophotometric Color Measurement Helps Perfect Tar Paper or Roofing Felt


Posted on February 13, 2018

When a contractor is building a structure from scratch, they have to ensure that the wooden frame is well-protected at all times. Just one afternoon of heavy rainfall could cause significant water damage and may even make the building more prone to rot, leaks, and mold in the future. This is why many contractors use tar paper or roofing felt to add an extra layer of protection to a structure. In fact, this construction material is a requirement under many building codes around the country.1 High-quality tar paper and felt is waterproof, which protects the building from environmental damage over time. And, in some cases, the paper may also improve the appearance of a building’s roof. The product provides a smooth, even base for the shingles to adhere to, allowing them to lay perfectly flush against the surface.

Because tar paper and felt are the base on which shingles and siding materials are later applied, product consistency is absolutely essential. Not only does the texture and thickness of the product have to be exact from roll-to-roll in order to provide an even base layer, color quality control is also important to facilitate correct markings and measurements. When you use a spectrophotometer to test your tar paper or roofing felt during the manufacturing process, you ensure color consistency in every roll.

Achieving Color Consistency in Tar Paper or Roofing Felt

Color consistency is important in tar paper and felt and can vary in based on the types of materials you use to create your products and how much asphalt you impregnate into the raw materials. Tar paper is either made with fiberglass or cotton rag scraps, which are then dipped in a thin layer of tar.2 Likewise, roofing felt is made from wood pulp products like cardboard and sawdust, which are soaked in a layer of thinned liquid asphalt. In both of these products, the addition of tar or asphalt causes the product to turn black. Generally, the more tar or asphalt you add to the material, the darker and heavier the final product will be.

This means that the color of your product may vary slightly if you add too much or too little asphalt or tar to the mix. Using a spectrophotometer, you can detect slight variations in color between one roll and the next, which may help you identify certain manufacturing inconsistencies, such as adding too much asphalt into the mix. If you add too much asphalt, then your product may be heavier than expected, which could make it difficult to install for certain uses, such as siding protection. And, if your product has too little asphalt in the mix, then it may be too lightweight, making it difficult to keep the product in place when it’s applied to rooftops.

Color consistency is also important for your customers. Tar paper and roofing felt are flexible, making it easy for contractors to maneuver pieces of it around uneven rooftops. But in order to ensure that the paper or felt rests flush against the roof and that each piece is cut to the roof’s exact measurements, contractors need to make chalk markings directly onto the tar paper or felt.3 Products that are one solid shade of black are easier to measure and mark because contractors can clearly see their markings against the background. If your product has areas of patchiness, or appears too grey in color, then it may be harder for contractors to see their measurements. Spectrophotometers can help you set a standard color for your products and ensure that each roll falls within that specified tolerance.

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