Adhesives: Solvent vs. Water Based

Solvent Based – Flammable/Non-Flammable

For many years the majority of adhesives were manufactured exclusively with hydrocarbon solvents, i.e. acetone, benzene, hexane, toluene, etc. These solvents were perfectly suited for dissolving various rubbers and resins to create the “perfect” emulsion that allowed these adhesives to be sprayed efficiently. As a result, these adhesives dry very quickly.

Though some of the solvents used then are still used today. However, there are air quality regions in the United States that either do not allow these solvents or allow their use in limited amounts.

These adhesives are considered “extremely flammable” and must be handled as such.

Non-flammable adhesives were introduced several years ago using non-flammable solvents. These solvents offered the safety of non-flammability, but also allowed for fast dry times. Typically, these adhesives were made with “chlorinated” solvents. Chlorinated solvents are organic compounds that contain chlorine atoms, i.e. 111-Trichloroethane and Methylene Chloride. 111-Trichloroethane was banned in this country several years ago. That left Methylene Chloride as the predominate solvent for making non-flam adhesives. However, this solvent has come under intense scrutiny over the years as a suspected carcinogen. It is still used today, but in limited quantities.

Water Based

Water based adhesives offer the best of both worlds – sort of. They are safe, high in solids (allowing greater coverage) and can be sprayed like the solvent based products. As in most things in this world, you have to give up something to get something.

Though water based adhesives are safe and sprayable, dry times are extended. Depending on atmospheric conditions, water based adhesives can take as long as 45 minutes to dry before bonds can be achieved. However, their open (or working) times are much greater, upwards of 2 hours.

Another misunderstanding of water based adhesives is that because they are higher in solids (sometimes 50% higher than solvent based), the common theory is water based adhesives offer greater coverage per square foot. In fact, these adhesives offer less coverage per square foot because of severe “over spray” issues. Where solvent based products are about 50% transfer efficient, water based products are only about 25% – 30% transfer efficient.