Many projects require some kind of adhesive or sealant, and it is important to use the one most appropriate for each task. Learn how to choose the right adhesive for your project.
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Some sealants prime or seal a surface, while others create a decorative, waterproof or durable joint. Most joint sealants have a waterproofing element. Many sealants are made for specific uses, such as in kitchens, bathrooms or on windows.
Joint sealants usually come in cartridges and need a separate dispenser to apply them. Dispensers vary in size and design, so check for compatibility. Most sealants come in an extensive range of colors. Latex sealants can be painted but those made with silicone can not. Sealant remover is available, but can damage some surfaces.
The sealant must cope with movement, such as that caused by temperature changes, in the materials they join. Some sealants are not very flexible, but dry to a relatively hard finish, and are recommended for use in bathrooms — however, check for resistance to mold. Other types are more flexible, and are used in glazing.
Curing and longevity
Most sealants form a skin fairly quickly, but take several hours, or even days, to dry or cure completely. High-modulus sealants give off strong acidic fumes while curing. A few brands are "fast-cure." A sealant should never get completely hard, because of the need for flexibility. Be sure to check the cartridge for the length of guarantee. High-quality sealants may be expensive, but they are easier to work with and last the longest.
Hot melted glue is applied with a glue gun and has a variety of applications, according to the model. Solid sticks of glue are melted inside the gun at the time of use. Guns require electrical power, and generate considerable heat, so follow all the manufacturer's safety guidelines when using one.
Standard dispenser for all-purpose use. High-performance dispensers are also available and are better for regular use, and for use with the more viscous sealants such as construction adhesive.
Several variations are available, designed for specific tasks. An example is a repointing gun with a refillable cartridge for applying pointing mortar.
Easy to use and control, this is the top-of-the-line sealant gun. Batteries are recharged much the same way as those of a cordless drill.
Cut off the tip of the cartridge. The opening at the tip determines the size of the caulk bead (Image 1).
Insert a metal pin into the tip of the cartridge and remove (Image 2).
Pull back the dispenser's plunger or rod and load the cartridge into the dispenser (Image 3).
To dispense the sealant, apply even pressure to the trigger. When you release the trigger, sealant will continue to dispense due to a buildup of pressure (Image 4).
Push the catch plate to make it stop. To store a half-used tube, insert a nail into its nozzle to prevent clogging, or replace the nozzle next time you use the tube (Image 5).
Water-based adhesives are an ecologically sound alternative to solvent-based products. They are non-toxic and low in VOCs (volatile organic compounds).
Follow all manufacturer's instructions when using an adhesive or sealant, because the chemicals involved can be dangerous. Ventilate your working area and wear all recommended protective equipment and clothing.
Excerpted from Do It Yourself Home Improvement
© Dorling Kindersley Limited 2009