Although a premium sign adhesive is the basis of a quality bond, it’s only the beginning. Proper application is essential for best results. This resource is intended to provide an application guide for many of your sign-bonding questions.
A: Below are best practices for preparing two-part adhesive and adhesive/sealant cartridges for optimum bonding results (refer to Figures 1-6).
A: Store the cartridge with the mix tip on. The Mix tip will serve as a cap to keep material fresh. Replace the mix tip prior to the next use.
A: Ask for LORD products at your local sign warehouse distributor. We have a network of authorized distributors in the US and Canada. Call our Customer Support Center (US & Canada) 877-275-5673 or contact us for more information on where to buy our sign adhesives.
A: Yes. All LORD adhesives in cartridges carry a 'Use by' date printed on the label and should be considered the final word for the shelf life of these products. Bulk containers "Use by" date is listed on the product certificate.
A: Yes. Surface tack is normal for LORD 400-series acrylic adhesives. Wipe the surface with alcohol or organic solvent after full cure to remove the tacky layer. Surface tack is only on the surface; properly bonded joints are fully cured.
A: Surface Preparation
All surfaces should be clean and free from oil, grease and dirt. As a minimum, wipe the surface with a clean, dry rag or blow off the surface with clean air.
Solvent wipes all surfaces with isopropyl alcohol. Do not use lacquer thinners, mineral spirits, gasoline, toluene or xylene as they may leave a residue that may cause bonding problems. Do not use commercial cleaners. These often leave a residue that may cause bonding problems.
Note: Each substrate and adhesive should be tested for the specific use in which it will be expected to perform. The information reported here is from laboratory studies and is intended only to provide general information regarding the ability of material to be bonded with LORD® Engineered Adhesives.
A: Joint configuration should be designed so that the basic stress is primarily shear, tensile or compressive with cleavage and peel stresses minimized on the bondline. Joints should be designed so that all of the bonded area equally shares the load. Illustrations provided depict both recommended joint design alternatives and joint design to be avoided.
A: Sometimes an adhesive is not appropriate. The rule of thumb is to use adhesives where the joint design is loaded in shear or compression, instead of peel or tension. Areas like butt joints or “T” joints do not always allow sufficient overlap for the adhesive to bond properly. Sometimes it is more appropriate to assemble these designs by welding, fastening, or with a combination of mechanical fasteners and structural adhesives.
A: LORD Structural Adhesives offer advantages to Sign Designers over welding and mechanical fastening. They bond dissimilar materials, provide improved appearance, insulate against galvanic corrosion and offer excellent environmental resistance. Adhesive bonding provides cost savings due to reduced labor costs and assembly time.
A: Refer to our Sign Adhesives Selector Guide or contact us for adhesive product selection.
This page also contains considerations that may influence your choice of adhesive. Please remember that these are guidelines and that you should always test for acceptable performance with your application.
A: Structural adhesives are thermoset polymers. They will not melt or change with environmental exposure, temperature or time. Acrylics and epoxies can withstand temperatures from -40°F to +400°F. Most urethanes are good up to 250°F with a low end slightly better than the other chemistries. Exposure to water, humidity, oil, gasoline, solvents, and other environmental factors won’t weaken bond strength in properly designed joints.
A: Understanding the type of chemistry being used is important. In general, acrylics excel at bonding unprepared metals, composites, and thermoplastics. Epoxies give the highest strength when bonding prepared metals, composites, and natural substrates such as stone and wood. Urethanes offer resiliency and flexibility and are candidates for joining composites, thermoplastics, natural materials and prepared metals.
A: Yes.
Note: Clamp or fixture the assembly prior to powder coating to avoid slippage during the powder coating process. The assembly should remain fixtured until the adhesive returns to room temperature and re-hardens.
LORD acrylic adhesives have excellent heat resistance characteristics up to 400°F, reducing the concern of possible degradation of the cured adhesive due to heat during the powder coating process. Allow the adhesive to fully cure before powder coating. Tested products include the Signlok Series, LORD 400 Series and LORD 800 Series adhesives.
However, it is important to keep in mind that at these higher temperatures, the hot tear strength is very low. At about 180°F, the adhesive will begin to soften. These lower strength values make it essential that the assembly is properly fixtured or placed to avoid slippage of the bonded pieces, especially if they are heavy. Mechanical or spot welds are frequently used in the industry to hold the assembly in place. Assemblies need to be fixtured to avoid any stresses during the time that the adhesives are soft and until adhesives return to room temperature and re-harden.
The integrity of the bond will remain unchanged, and in fact increase, once the assemblies have returned to room temperature.
For complete instructions, refer to Powder Coating after Bonding with LORD® Acrylic Adhesives.
A: When bonding larger assemblies involving dissimilar materials, such as aluminum or steel to polycarbonate or acrylic, attention should be placed on the expansion and contraction of the materials. Differences exist in the expansion coefficients of metal and plastic. Substrates will expand and contract at different rates with temperature changes. There are two factors to consider:
1) The design must be flexible enough to accommodate the expansion, and
2) The adhesive must be strong enough to tolerate the stresses that the thermal expansion produces.
LORD urethane adhesives (LORD 7542, LORD 7610DTM) provide flexibility and prevent stress fractures and/or bond failure of the plastic materials. Prime the bare metals, scuff the plastic, and bond with a LORD urethane structural adhesive.
LORD acrylic adhesives (SignlokTM 403, Signlok 406, LORD 400 Series, Signlok 810, Signlok 204) provide exceptional structural strength and are particularly formulated for assemblies with a bare metal substrate. However, they may not provide as much flexibility as needed for outdoor or large cross-bonded assemblies.
A: Outdoor metal installations will benefit from using LORD 400 or 200 Series because these adhesives provide excellent corrosion and environmental resistance.
Outdoor installations may require greater adhesive flexibility because the size of the assembly is large, if the metal is painted, or if the assembly will need to tolerate flexing. If these factors are present, consider bonding an outdoor assembly with LORD 7542 or 7610DTM adhesive. Prime bare metal surfaces when using LORD 7542 adhesive.
Indoor applications generally do not need to accommodate temperature or environmental changes as much as outdoor applications and can be bonded with the adhesive recommended based on the materials.
A: Depending on the materials and application, LORD has adhesive solutions for common stud bonding applications:
A: Large pieces or panels may need to accommodate movement in the assembly. LORD 7542 or 7610DTM adhesive may be more appropriate for bonding applications requiring greater flexibility. Prime bare metal surfaces when applying LORD two-part urethane adhesives, such as LORD 7542 adhesive, to metal.
A: Large assemblies with a tight tolerance, like mounting a sign face, may benefit from the LORD No-Mix Series that allows for an indefinite open time for bonding. No-mix adhesives components, also known as "honeymoon" adhesives, are applied on the opposite mating surfaces of the substrates to be bonded. Curing does not start until the parts are brought together. Recommended bondline thickness is 10 mils and can be no more than 20 mils. No-Mix options include LORD 201 and 204 used with LORD Accelerator 4.
A: Laminating is the process of bonding two or more layers of material together with an adhesive.
Sign designers can use LORD 201 or 204 adhesives in combination with LORD Accelerator 4 to laminate acrylic, bare metals, painted metals, aluminum composites, polycarbonate, vinyl and high-density urethane foams. No-Mix adhesive components are applied on the opposite mating surfaces of the substrates to be bonded. Curing does not start until the parts are mated.
The recommended bondline thickness of the LORD 201 or 204 adhesive is 10 mils. Estimate 2 oz. of Accelerator 4 per 1/10 gallon cartridge of LORD 201 or 204 adhesive. Coverage would be 16 sq. ft. per 1/10 gallon cartridge or 160 sq. ft. per gallon (ten 1/10 gallon cartridges).
LORD 201 adhesive has a thinner consistency and is best for brushing applications. LORD 204 adhesive is non-sag and best to spread with a notched trowel.
A: Sign Designers can use readily available grades and standard foam thicknesses to manufacture a variety of designs by layering the foam and laminating the layers. Laminating reduces the cost and the need for storage space and inventory of various grades and thicknesses of sign foam.
Brush or roll LORD 7650 with a recommended dry film thickness of 2-4 mils (.002-.004") or a wet film thickness of 3-6 mils (0.003-0.006"). LORD 7650 can also be applied by spray if done in a spray booth with proper ventilation.
A: To calculate coverage, one gallon of LORD 7650 will cover approximately:
Once the adhesive has been applied, wait approximately 20-30 minutes for a good tack to develop as the solvent evaporates. Mate the substrates, slide to reposition, and apply uniform pressure with a board and/ or weights. The assembly should remain under pressure for 10-24 hours at 75°F (24°C) to reach handling strength. LORD 7650 will fully cure in 1 to 5 days depending on humidity. Once fully cured, the bonded area can be cut on a router to the desired shape. Finish with a primer or sanding.
A:
A: Apply the adhesive to the part in a manner that will ensure complete adhesive coverage to the bond area. (Refer to chart below). The rule of thumb is to dispense a bead about one-sixth the diameter of your bond joint.
Allow for variations in bondline thickness around the periphery of the part. While a 0.010" (0.254 mm) bondline thickness is ideal, the fit of the parts to be bonded is not always ideal. Therefore, increase the bead size dispensed in areas of "poor fit" to assure adequate coverage.
A small amount of squeeze-out along the bondline may be desirable for use as a sealant and also as a visual assurance of adhesive presence. However, if this squeeze-out interferes with the aesthetic appearance of the final product, it should be removed before the adhesive completely cures. Refer to the product literature for product working time and remove the squeeze-out before the working time has elapsed.
The chart below provides a general guideline on what bead diameter to dispense to ensure complete coverage of the bond joint at various bondline thicknesses.
A: Mate the materials carefully to properly align the pieces. If the materials need to be re-positioned after mating, SLIDE the pieces into position. Do not lift or separate the pieces as this can allow air into the bondline and cause voids, resulting in less than optimum coverage and strength.
A small amount of squeeze-out along the bondline may be desirable for use as a sealant and also as a visual assurance of adhesive presence. If the squeeze-out interferes with the aesthetic appearance of the final product, it should be removed before the adhesive completely cures. Refer to the product literature for product working time.
A: For best results, follow these guidelines:
A: Immediately after the parts are positioned correctly, they must be weighted with even pressure until handling strength is achieved. Some of the means typically used to accomplish this are clamps, boards/stiffeners, weights, mechanical fasteners or braces.
A: Read-through is a condition where you can see the footprint of the adhesive through the material. This is caused by shrinkage that results in a pull on the bonded materials. Read-through can occur on surfaces that are high gloss, high polish, or have a mirrored finish. Thin gauge metals less than 0.030" are more susceptible to read-through.
Sandwich panel material, such as DiBond® or Alucobond®, which are aluminum composite panels that are typically 0.3 to 0.5 mm thick aluminum sheets covering a solid polyethylene core with a total thickness of 3 mm or more, or similar panels from any manufacturer, may also be susceptible to read through.
Following are some tips to avoid read through:
A: Signlok 810 Low Read-Through (LRT) acrylic adhesive is a flexible adhesive system specifically designed for bonding metals, such as aluminum, galvanized steel and CRS, and engineered plastics, such as PC-ABS and ASA. Signlok 810 adhesive delivers fast cure speed and strong bonding with minimal read-through.
A: LORD offers an extensive line of UL Approved Adhesives that bond various substrates.
A: Because adhesives contain chemicals, you need to wear protective equipment and clothing. Safety glasses or goggles and gloves should be worn when applying adhesives. The area should be sufficiently ventilated to protect you from fumes and vapors. Always refer to the Safety Data Sheet (SDS) of the adhesive for safe use guidelines
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