Water-Based Adhesives – Information and Overview - Hotmelt.com

Industrial adhesives service thousands of different companies across a number of industries, including packaging, woodworking, graphic art, and more. Although some forms are more commonly used than others, all of them are designed to serve a specific application depending on the job or product you are dealing with. While hot melt adhesives tend to be the most popular, other forms like water-based and reactive adhesives are also available, and can offer you the same quality results as a hot melt adhesive, depending, again, on the job at hand.

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For this article, we will be taking a closer look at water-based adhesives, the types that are available on the market, their applications, and what industries are currently utilizing water-based adhesives on a regular basis. Let’s get started.

What Are Water-Based Adhesives?

Before we can go into details about water-based adhesives, we first have to understand what they are. An adhesive, or glue, is a mixture, either in liquid or semi-liquid form that is used to bond one surface to another. Most all adhesives are polymer based, and are made from either natural or synthetic sources. Adhesives are also specially formulated for specific applications, depending on the type of adhesive and the industry you are working in.

Water-based adhesives are supplied as pre-mixed solutions, or are formulated as dry powders, which producers and distributors must then mix with water in order to obtain its adhesive properties. These properties are obtained when water is either lost from the glue line by evaporation or is absorbed by the substrate. Because of this, it is important to use at least one permeable substrate when applying water-based adhesives. 

Because the polymers in water-based adhesives are water soluble, the bonds that are formed between surfaces are more susceptible to moisture and water, although some kinds, like plant and casein glues, are made with a base material that is insoluble at room temperature. Although this has improved the resistance of such adhesives to the effects of water and moisture, water-based solution adhesives are still perishable, and therefore contain a shorter storage life.

Types of Water-Based Adhesives and Their Differences

There are four main types of water-based adhesives: vegetable glues, animal/protein glues, resin cements, and latex cements. Each of these different adhesives is uniquely formulated to serve their own specific purposes. Depending on which adhesive you’re using, the resulting bond will come out as either a solid resin or a more film-like finish, but all are solvent free, making them safe to use in close quarters and non-ventilated areas. Let’s take a closer look at each of these types of water-based adhesives.

1. Vegetable Glue/Starch (Dextrin) Adhesives

Vegetable adhesives are one of the more popular water-based adhesives types. These adhesives contain a starch base and result in a more frail finish. For that reason they are commonly used for in the paper industry for such applications as bookbinding. These adhesives are known to be very durable when used with material like paper, but their vegetable base does make them more susceptible to breakdown when exposed to water.

2. Animal/Protein (Caesin) Adhesives

Animal, or protein adhesives are derived from either animal organs that are processed specifically for the purpose of making hot glue, or from proteins found in animal milk, which is used to make casein glue. While hot animal glue is primarily for quick-fix/quick-set applications, casein glue, which is more resistant to water and moisture, is used primarily in the beer and wine bottling industry. 

3. Resin/Polymer Acetate Adhesives

The primary components in resin water-based adhesives are vinyl acetate, ethylene vinyl acetate, and acrylic resin emulsion polymers. Emulsions are mixes of liquids that cannot really be blended. To make these kinds of water-based adhesives, water is mixed with the polymers polyvinyl acetate (PVA) and ethylene vinyl acetate (EVA) to produce a bright white liquid mixture. Once the adhesive has been applied and allowed to dry, however, it produces a clear, flexible bond that is also used for paper, but also for wood and plastic.

4. Latex Adhesives

Latex cements, another group of water-based adhesives, are made from emulsified elastomers, or rubbers. Like polymer adhesives, latex adhesives must be applied to the substrate surface and allowed to dry into either a solid bond, or a more crude, flexible bond, depending on the formulation. These types of water-based adhesives are primarily used for bonding stamps, envelopes, fabric, leather, and wood.

Major Markets

There are many industries and specific applications that benefit from the use of water-based adhesives. These include the packaging and bottling industries, paper, woodworking, plastic, and fabric industries. As was noted above, some specific applications for water-based adhesives within these various industries include envelope and stamp production, bookbinding, and labeling for alcoholic and soft drink beverage companies. Water-based adhesives also serve an important purpose in product assembly in industries like packaging and woodworking (furniture products and boxes), as well as lamination applications in the graphic arts industry.

Whether you've made a mistake or you're replacing an old fixture, there are times you'll need to unglue Polyvinyl Chloride (PVC) pipe. However, this is impossible, as nothing will dissolve the solvent between the pieces of PVC [source: This Old House]. Fortunately, there is a solution when it comes to dealing with stubborn PVC pipe glue.

With the right tools and approach, you can "unglue" PVC pipe. The key is to follow these tips and know which method to avoid!

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Understanding PVC Adhesives

Before delving into the process of ungluing PVC pipe, it’s important to understand the nature of PVC adhesives. PVC glue, also known as PVC cement, is a solvent-based adhesive that works by melting the surface of the PVC pipe and fitting. When the solvent evaporates, the two pieces of PVC fuse together, creating a bond that is often stronger than the pipe itself.

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Tools You'll Need to Glue PVC Pipe

Here's what you'll need:

Hacksaw

A hacksaw is useful when you are unable to physically separate the glued PVC joint by heating and twisting. In such cases, you can use a hacksaw to carefully cut through the PVC pipe close to the joint. This allows you to remove the section of the pipe that is glued to the fitting. It's a practical tool for cutting PVC pipes with precision and control.

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Purple Primer

Purple primer is used to clean and soften the PVC pipe's surface before applying PVC cement for reattachment. It helps in removing any dirt, oil, or ordinary adhesive remnants from the surface of the pipe, ensuring a clean area for the new adhesive.

The primer also softens the top layer of the PVC, which allows for a better bond when the new PVC cement is applied. Its purple color helps to visibly indicate the areas where it has been applied, ensuring comprehensive coverage.

Clear PVC Cement

After using the primer, clear PVC cement is applied to create a new bond between PVC pipes or fittings. This solvent cement works by chemically fusing the pieces of PVC together, creating a strong and reliable seal.

The clear PVC pipe cement is preferred in applications where aesthetic appearance matters, as it leaves no color residue on the pipe. Remember, not all universal solvent cements are created equal!

A New Fitting and Coupling

When a PVC pipe is cut to remove a glued joint, a new fitting and/or coupling may be necessary to reestablish the connection. The new fitting can be attached to the existing pipe using the PVC primer and cement. Couplings are especially useful when you need to connect two cut pipe ends together, providing a secure and leak-proof joint.

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How to "Unglue" and Glue PVC Pipes

Here's what to do:

1. Cut out the problem joint Use a hacksaw to cut the PVC pipe flush along the fitting of the joint that you wish you could unglue [source: This Old House].
2. Get a new fitting and coupling Find a new fitting that satisfies your new needs. Find a coupling that matches the old fitting you didn't cut out and the new one you're adding.
3. Prime the PVC Apply a thin layer of purple primer to the ends of your PVC fittings. Also apply the primer to the inside of the coupling. Let the primer dry for a few minutes.
4. Glue the new joint together After the primer is dry, coat the primed areas of the pipes and coupling with clear PVC cement. Some multi-purpose cement glues aren't approved for all pipe uses, so make sure you're using a PVC-specific type. Push the pipe into the coupling while turning it a quarter turn. Make sure the fittings don't pop out before the adhesive hardens. If possible, wipe away any excess glue from the outside of the pipe before it dries.

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Avoid the Heat Method

Using a heat gun or propane torch on PVC pipes poses significant risks due to the nature of PVC material and the high temperatures involved. PVC, when exposed to high heat, can release toxic fumes including chlorine gas and dioxins, which are harmful if inhaled and can cause respiratory problems, eye irritation, and other health issues. The risk is compounded in poorly ventilated areas where these fumes can accumulate.

Moreover, applying heat to PVC requires careful control; excessive heat can lead to the pipe melting or deforming, compromising its structural integrity and potentially causing leaks or breaks in the plumbing system. There's also a fire hazard to consider, as the high temperatures can ignite the PVC or nearby flammable materials. Always use safety goggles, avoid skin contact, and work in a well ventilated area.

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Tackle PVC Projects With Confidence

Ungluing a PVC pipe is a challenging but achievable task. Once that's done, gluing PVC pipe in the fashion you want is a cinch!

By following these steps and taking necessary safety precautions, you can successfully separate and replace PVC joints in your plumbing projects. Remember, if you’re unsure about the process, it’s always best to consult with a professional plumber.

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This article was updated in conjunction with AI technology, then fact-checked and edited by a HowStuffWorks editor.

PVC Pipe FAQ

Can you unglue PVC pipes?

You can use a purple primer to unglue it. For this, apply the primer and let it dry for a while. When it’s dried, apply the PVC cement to the joints and couplings. Now, turn the pipe stealthily to stretch it out of its glued area. Another DIY way is to use a hair-dryer on a high heat setting to melt the glue. When given heat for a few minutes, the bond should break and fittings will pop out.

What is the preferred tool for cutting PVC pipe?

An easy and preferred tool to cut PVC pipe is a handsaw. You can use any saw for cutting, but a backsaw or hacksaw is an ideal tool with greater flexibility.

What glue works best on PVC pipe?

Using ordinary adhesives to join PVC pipes will not work. So, for a good fitting, Oatey glue is the best PVC glue. It has heavy-duty chemical solvents that provide leak-proof air-tight fittings. Moreover, it is specially formulated to melt the PVC surface for instant hardening to give added strength.

Can you use silicone to seal PVC pipe?

Yes, silicone is a fast and easy way to seal your PVC pipes. However, you should not apply silicone on a wet pipe. First, dry out your PVC pipes completely and then apply the silicone.

What can you use instead of a PVC glue?

If your application is not very demanding, you can use hot glue, contact cement or super glue as they also provide good adhesive strength to the PVC joints. However, they may not be reliable in the case of a pressurized water line that demands strong adhesion. ​ Cite This!

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