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Seams always have been and always will be the most critical part of the installation operation, and seam treatments are no exception.  Done correctly, seams can be a thing of beauty that will last for the life of the material, but done incorrectly can be a disaster, with little or no fixing; usually a seam complaint will result in total replacement. 

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Seam Sealers

Photo 1 - Seam sealers: Seal sealers date back to the mid 1960s and were required to fuse seams of rotogravure materials together and secondly to keep dirt out of seams. The main chemical in seam sealer is Tetrahydrafuran (THF) and is a liquid that chemically fuses a seam together.  Still used today, many installers will misuse THF, thinking it will work as a coating applied to the surface of the material only to find out it will fail in a few short months.

The second misuse is applying the THF when it is cold.  THF-based seam sealer works on a thermo-fusion process.  When applied the chemical reaction develops heat, causes a gentle swelling of the material, and the fusion develops as the solvents escape.  If it is below 55°F (12.8°C) it is too cold for the thermo-fusion process to develop and you have basically wasted your time, because it is going to come apart, over time.

Photo 2 - Applicator tips: There are a large assortment of applicator tips in the market; some have fins and some have needles at the tip.  Each manufacturer has their specific applicator tip.  It is a matter of getting used to the type applicator tip to be used.  My favorite is the needle tip, but the fin type works well.  The key is to get the seam sealer down into the seam without disturbing the edges of the material.

Photo 3 - Seal sealers for different gloss finishes: Today these same seam sealers are still used, along with some which are THF-based that are used for different gloss levels and different finishes on materials These types very often need to be mixed and are generally a one-time use.  Be sure to check the manufacturer recommendation for the proper seam treatment to be used.

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Photo 4 – Application: As I indicated, I prefer the needle applicator bottle, but even more I want to be sure the bottle is almost full.  I can flow a smoother bead of sealer if the bottle has little or no air.  The more air there is in the bottle the more you have to squeeze the bottle to get the seam sealer to flow out. A seam seal will not compress like air and requires less pressure to get an even flow.

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Seam Seal and Wipe for Materials with Finishes

Photo 5 - Components for the seal and wipe procedure: The seal-and-wipe seam sealing system is very much like the regular seam sealing except you wipe the residual bead of seam sealer off the surface of the material.  Some manufacturers recommend mineral spirits and/or naphtha (lighter fluid). Once the bead has been applied allow the sealer to set on the seam 3 -5 minutes, which allows the fusion to develop and then using a clean white cloth dampened, with whichever solvent is recommended, remove the existing bead of seam sealer.  Do put the solvent directly on the seam and/or wash out the seam sealer with too much solvent.

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Seam Bonding

Photo 6 - Adhesive bottles: Several manufacturers have an option to either heat welding or seam sealing and that is a seam bonding system.  I find it useful on linoleum seams and seams of both homogeneous and heterogeneous commercial products. While this system is not as good as a heat welded seam, it does work well under certain circumstances where foot traffic is not an issue.

Once the seam is cut (“net”), apply a bead of seam adhesive about 1/8” in diameter to one edge and the second edge is then placed up to the first edge of  the seam, forcing the adhesive up and out of the seam.  The seam adhesive is then cleaned up and allowed to dry.  The key to success of this process is to get the adhesive residue off the material without leaving a milky residue or by washing the seam adhesive out of the seam. 

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Seam coatings

Seam coatings are the most recent of the seam treatments and have been around for well over a decade.  The seam coating is not a fusion system, but a coating system that is strong enough to hold two seam edges together.  Seam coatings come in two gloss levels. It is critical that the proper gloss level is used as it is difficult to make corrections. 

The key to a successful seam coating is strict attention to detail when mixing.  The low gloss is especially critical.  The normal time for mixing is about five minutes. Then, there is a cleaner that is used on some materials to aid in the bonding of the coating to the surface of the material. You need to check with the manufacturer for seam coating recommendations and gloss levels.

Photo 7 - Application of coating: Once the seam is cleaned and ready for the coating, it is necessary to trim about 1/32” off the nozzle to allow the coating to flow smoothly.  When flowing the seam coating, it is necessary to have about 1/16” of coating on either side (1/8” total) of the seam.  Failure to get the coating on both sides of the seam will allow the seam to open up over time.  Finally, it is necessary to maintain a smooth bead of seam coating.  Some installers will follow along a straight edge, while others will keep a cloth under their hand to allow your hand to slide smoothly along the seam.