Have you ever tried to glue two surfaces together with PVA glue, only to find that it simply won’t stick? Despite its versatility and popularity, there are some materials that PVA glue just can’t bond with. Understanding what these surfaces are and why they present a challenge is crucial for achieving reliable and long-lasting adhesive bonds. In this article, we’ll explore what PVA glue is, how it works, and most importantly, what it doesn’t stick to. We’ll also provide some tips on how to use PVA glue effectively and offer alternatives for those stubborn surfaces. So, let’s dive in.
What is PVA Glue?
PVA glue is a widely used adhesive that is essential in many DIY projects. PVA stands for Polyvinyl Acetate and is a synthetic polymer that is water-soluble and able to bond porous surfaces together. Its popularity comes from its ability to glue together wood, paper, fabric, and other materials, and is a staple in most homes and offices.
The adhesive properties of PVA glue are due to the polymerization process that occurs when the glue is exposed to air. The water content in the glue evaporates, causing the polymerization process to occur, which leads to the formation of a strong bond between two surfaces. PVA glue works best on porous surfaces and can be painted over once it is dry.
An interesting fact is that PVA glue can also be used in the manufacturing of some types of paper. When applied to paper fibers, the glue creates a chemical bond that enhances the paper’s strength and texture. This process of papermaking has been around for centuries, but the use of PVA glue today makes it faster and more efficient.
While PVA glue is versatile and easy to use, it is not suitable for use on all surfaces. For instance, it may not be effective on plastics, metal, or greasy surfaces. To achieve a strong bond, it is important to understand the surface you are gluing and choose the appropriate adhesive.
In the next section, we will explore surfaces that do not work well with PVA glue.
What Does PVA Stand For?
If you’re new to the world of adhesives, you may be wondering what exactly PVA glue is. PVA is an acronym which stands for polyvinyl acetate. This type of glue is known for its effectiveness in bonding porous surfaces such as paper, wood, and fabric. It is a popular choice for school and craft projects, as well as household repairs. Fun fact: PVA glue is not made from horses, unlike animal-based adhesives such as casein glue and rugby glue which are made from animal hides and bones.
How Does PVA Glue Work?
When it comes to how PVA glue works, there are a few key things to keep in mind. Firstly, it is important to know that PVA glue is a water-based adhesive. This means that as the glue dries, the water evaporates causing the glue to harden and bond the two surfaces together.
The Polymerization Process
When PVA glue is applied to a surface, it starts to dry almost immediately. As it dries and the water begins to evaporate, the polyvinyl acetate (PVA) molecules in the glue begin to link together in a process called polymerization. This process forms long chains of molecules that create a strong bond between the two surfaces being glued together.
The Importance of Porous Surfaces
PVA glue is most effective when used on porous surfaces such as paper, wood, and fabric. This is because these materials are able to absorb the water in the glue, allowing it to dry and harden more effectively. Non-porous materials such as plastic and metal don’t allow the glue to be absorbed, leading to a weaker bond.
Limitations
While PVA glue is a versatile adhesive that can be used for a variety of projects, it does have some limitations. Firstly, it is not suitable for use on non-porous surfaces, as previously mentioned. Additionally, PVA glue is not waterproof and shouldn’t be used for outdoor projects or in areas that are likely to get wet.
PVA glue can also struggle to bond with oily or greasy surfaces. It’s essential to prepare the surface properly before applying the glue. To achieve the best results, clean the surface to remove any dirt, dust, or oils that might be present.
PVA glue is a versatile and effective adhesive that works by polymerizing the PVA molecules in the glue to form a strong bond between two surfaces. While it has some limitations, it is an excellent choice for most porous surfaces and can be used for a variety of projects.
What Does PVA Glue Not Stick To?
When it comes to using PVA glue, it’s essential to know what surfaces it is not suitable for. Despite being a versatile adhesive, there are a few materials that PVA glue won’t stick to.
Plastic: PVA glue is not effective in bonding plastic materials. Since plastic is non-porous and flexible, it can’t get a good grip on it, and the bond will break easily. If you need to glue plastic, consider using a suitable adhesive such as epoxy or cyanoacrylate (super glue).
Oily or Greasy Surfaces: PVA glue won’t stick well to any surface that has oil or grease on it. The greasy substance prevents the glue from penetrating the surface and adhering correctly, hence affecting the bond’s quality and strength. It’s advisable to clean the surface with a suitable solvent before attempting to glue, which will help to remove grease and oil residues.
Metal: PVA glue is not appropriate for gluing metal surfaces. Metal is a nonporous material, and as such, it doesn’t bond well with PVA glue. Metal surfaces are often smooth and polished, which can affect the strength of the bond. Consider using specialized metal adhesives such as epoxy or cyanoacrylate glue.
Glass: Similar to metal surfaces, glass is another material that PVA glue doesn’t work well with. Due to its smooth surface and non-porous nature, the glue won’t form a strong bond. If you need to glue glass, consider using specialized glass adhesives, such as UV-curing adhesive or silicone glue.
Wax or Soap-Based Products: PVA glue doesn’t adhere well to surfaces that have wax or soap-based products. The presence of such products affects the glue’s ability to bond with the surface, and it can lead to the bond’s failure. It’s recommended to take proper precautions before gluing surfaces that have wax or soap-based products.
Wet Surfaces: PVA glue is not suitable for bonding wet surfaces. The adhesive may not dry correctly, which can lead to the bond breaking down over time. It’s essential to ensure that surfaces are dry before applying PVA glue to get a strong bond.
Knowing what surfaces PVA glue won’t stick to is crucial for any DIY project, repairs, or crafting. If you need to glue any of the above materials, consider alternative adhesives to achieve a strong and lasting bond.
Plastic
Plastic is a widely used material in everyday life due to its versatility and affordability. Although PVA glue works well on many surfaces, plastic is not one of them. PVA glue struggles to adhere to plastic surfaces as their non-porous nature makes it difficult for the glue to seep in and create a strong bond. If you are looking to use glue on plastic, it is important to know that not all plastics are the same. Different types of plastic have unique compositions, which may affect their compatibility with PVA glue. So, before using PVA glue on plastic, it is essential to determine the type of plastic first. Otherwise, using alternative adhesives may yield better results.
Oily or Greasy Surfaces
When it comes to using PVA glue, it’s important to note that it does not stick well to oily or greasy surfaces. This is because the oils can create a barrier, preventing the glue from properly adhering to the surface. If you’re working with a surface that is greasy or oily, it’s important to clean it thoroughly before using PVA glue. You can use soap and water or a degreaser to remove any oils or grease from the surface. Once the surface is clean and dry, the PVA glue should adhere properly.
It’s also important to note that PVA glue is not ideal for bonding materials that will be exposed to heat or moisture, as it can break down and lose its grip over time. So, if you’re working with a surface that is likely to be exposed to heat or moisture, you may want to consider using a different type of adhesive.
If you’re looking for an alternative adhesive for oily or greasy surfaces, epoxy may be a good choice. Epoxy is a two-part adhesive that is known for its strong bonding capabilities. It can be used on a variety of surfaces, including metals, plastics, and ceramics. Like PVA glue, epoxy requires a clean surface in order to properly bond. However, it is more tolerant of oily or greasy surfaces and can often bond to surfaces that PVA glue cannot.
While PVA glue is a versatile adhesive that can be used on a variety of surfaces, it is important to be aware of its limitations. By understanding what PVA glue does not stick to, you can ensure that you are using it properly and getting the best results possible.
Internal link: Tylo glue is a type of adhesive that is often used in cake decorating and other food-related crafts because of its ability to dry quickly and remain strong even in humid conditions.
Metal
Metal is another type of surface that PVA glue may not stick to very well. This is because metals such as copper, iron, and aluminum tend to be smooth and nonporous, which can make it difficult for the glue to adhere properly. Additionally, metals are often coated with oils or other substances that can prevent glue from bonding to them.
| Metal Surface | PVA Glue Adhesion |
|---|---|
| Copper | Weak |
| Iron | Weak |
| Aluminum | Weak |
| Stainless Steel | Strong |
Stainless steel may be an exception to this, as it is often textured or roughened to improve adhesion. If you need to bond PVA glue to a metal surface, it is important to clean the surface thoroughly beforehand to remove any oils or debris. Sanding or etching the surface can also help improve adhesion.
However, for a stronger bond on metals, other types of adhesive may be a better choice. Epoxy, for example, is a two-part adhesive that creates a very strong bond on metals. Super glue and silicone adhesive may also work well for certain types of metal.
If you want to learn more about adhesives and their properties, check out our article on what Elmer’s school glue is made of or what casein glue is made of.
Glass
Glass surfaces can be notoriously difficult to stick together with PVA glue. This is due to the smoothness and non-porous nature of glass, which makes it difficult for glue to adhere to the surface. Using PVA glue on glasses doesn’t offer a strong and stable bond, as it will peel or flake away within a short time.
It is important to note that, even if PVA glue appears to hold the glass surface together initially, it may not be strong enough to withstand the weight or pressure of the item that is being glued, causing it to eventually break apart.
The following table summarizes PVA glue’s adhesion to Glass surface:
| Surface Type | PVA Glue Adhesion |
|---|---|
| Clear Glass | Poor |
| Opaque Glass | Poor |
| Frosted Glass | Poor |
| Mirrored Glass | Poor |
When working with glass, it is best to use an alternative adhesive such as epoxy, silicone, or cyanoacrylate (super glue). These provide a stronger and more reliable bond on glass surfaces. Epoxy will create a permanent, waterproof bond, while silicone will work best on flat, non-porous surfaces. Cyanoacrylate, on the other hand, can bond quickly and is ideal for small and lightweight items.
In case you’re interested, PVA glue is a water-based adhesive made from a combination of polyvinyl acetate and water. It is non-toxic, dries clear, and is easy to clean up. However, because of its limited sticking power on certain surfaces like glass, it is important to consider your adhesive options carefully before starting a project.
Wax or Soap-Based Products
When it comes to PVA glue, it doesn’t work well on surfaces that are coated with wax or soap-based products. The reason for this is that these surfaces have a slippery texture which makes it difficult for PVA glue to adhere to them. Wax, in particular, does not bond well with PVA glue.
Wax: Wax-based surfaces that PVA glue does not stick to include candle wax, car wax, and furniture wax. Applying PVA glue to a wax-based surface may cause the glue to peel off easily. It is important to avoid using PVA glue on wax-based surfaces.
Soap-based Products: PVA glue also does not bond well with soap-based products. Soap residue on surfaces can cause a barrier between the glue and the material, preventing them from bonding together. This includes surfaces such as soap dispensers, soap dishes, and soap residue on a sink. It’s best to clean the surface thoroughly before applying glue to ensure it will stick as intended.
To summarize, it is best to avoid using PVA glue on surfaces coated with wax or soap-based products. Instead, consider using alternative adhesives such as super glue, epoxy, or silicone adhesive, which may be better suited for these types of surfaces.
Tips for Using PVA Glue Effectively
If you’re working with a surface that isn’t coated in wax or soap, there are a few tips to keep in mind when using PVA glue.
- Prepping the Surface: Make sure the surface is clean and dry before applying glue. Any dirt or moisture can affect the strength of the adhesive.
- Using the Right Amount of Glue: Using too much glue can make the bond weak and take longer to dry. Follow the manufacturer’s instructions for the right amount.
- Allowing Time for Drying: It’s important to give PVA glue enough time to dry completely. This could take anywhere from a few hours to 24 hours, depending on the amount of glue used and the humidity level of the environment.
- Clean Up: If you accidentally get glue on your skin or a non-intended surface, clean it up with a damp cloth before it dries. Once it dries, it becomes more difficult to remove.
Wet Surfaces
When it comes to using PVA glue, one thing to keep in mind is that it will not stick well to wet surfaces. This is because the moisture on the surface can interact with the glue, making it less effective in forming a bond.
Why won’t PVA glue stick to wet surfaces?
PVA glue is water-based, so applying it to a wet surface can cause it to break down and not adhere properly. Also, if the surface isn’t fully dry, the glue may not penetrate the material and form a strong bond.
How can you use PVA glue on a wet surface?
If you need to use PVA glue on a wet surface, it’s important to dry it completely before applying the glue. You can use a towel or paper towel to wipe the surface and remove any excess moisture. Alternatively, you can use a hair dryer to quickly dry the surface.
| Surface | Recommended Precaution |
| Water-resistant materials | Use a sealant or primer to make the surface less absorbent before applying glue |
| Wet paper or cardboard | Dry the paper or cardboard with a hair dryer or allow it to air dry before applying glue |
| Wet wood | Dry the wood with a towel, paper towel, or hair dryer, and then sand the surface to create a rougher texture for better adhesion |
What are the consequences of using PVA glue on a wet surface?
If you apply PVA glue on a wet surface without drying it completely, the glue may not form a strong bond, leading to your project falling apart or not being as secure as you intended.
To ensure that your PVA glue projects are successful, it’s important to wait until surfaces are fully dry before applying the glue. It’s also wise to use a sealant or primer layer on water-resistant materials, such as wood, before using PVA glue to ensure better adhesion.
If you’re having trouble with PVA glue not adhering to a particular surface or material, there are alternative glues available, such as epoxy or super glue, that may be more effective for those applications.
Internal link: How Long Does Glue Take to Dry?
Tips for Using PVA Glue Effectively
Using PVA glue effectively can make a big difference in the outcome of your project. Here are some tips to help you get the best results:
Before applying PVA glue, it is important to prepare the surface properly. The surface should be clean and dry, as any dirt or moisture can compromise the bond between the glue and the material. If the surface is not properly prepped, the bond may not be strong enough, and the project could fall apart.
Using the right amount of glue is crucial for a strong bond. If too little glue is used, the bond may be weak, and if too much glue is used, it can lead to messy and uneven glue lines. A good rule of thumb is to apply a thin, even layer of glue to the surfaces to be joined.
After applying the glue, it is important to allow enough time for it to dry completely. This will depend on the amount of glue used, the type of material being bonded, and the temperature and humidity of the environment. As a general guideline, PVA glue should be left to dry for at least 24 hours before the bonded item is subjected to any stress.
Cleaning up after using PVA glue is important to prevent any damage to surfaces or tools. Use a damp cloth to wipe away any excess glue that may have seeped out during the application. If the glue has already dried, use a scraper or sandpaper to remove it.
It’s also important to note that PVA glue has a shelf life, and using expired glue can result in weaker bonds. Check the expiration date before using your PVA glue.
Alternative glues for difficult surfaces include epoxy, super glue, and silicone adhesive. Each of these has its strengths and weaknesses, so be sure to research and choose the appropriate glue for your specific project.
Following these tips for using PVA glue effectively can help you achieve a strong and durable bond in your projects. Remember to always prep the surface properly, use the right amount of glue, allow enough time for drying, and clean up after use. For more information about glue, check out who owns it glue.
Prepping the Surface
When it comes to using PVA glue, prepping the surface where you’ll be applying the glue is crucial for a strong and long-lasting bond. Proper surface preparation ensures that the glue adheres well and the final result is neat and seamless. Before applying PVA glue, be sure to remove any loose debris, dirt, or grime from the surface. You can use a damp cloth or sandpaper to clean and roughen the surface to improve the adhesion of the glue. In this way, you’ll optimize the glue’s strength and durability. Now that you know the importance of prepping the surface let’s dive deeper into the topic and check the details.
Using the Right Amount of Glue
One of the most important factors in using PVA glue effectively is applying the right amount of glue. Using too little glue may result in a weak bond, while using too much can cause the glue to take longer to dry and potentially create a messy, excess glue residue.
When using PVA glue, it’s essential to use the right amount for the job. The amount of glue needed will depend on the surface you’re working on and the size and weight of the materials you’re trying to bond.
Here is a guide to determining the right amount of glue to use for different projects:
| Project Type | Recommended Amount of Glue |
|---|---|
| Bookbinding | Thin layer of glue on spine and cover materials |
| Woodworking | 1/4 teaspoon of glue per square inch of wood surface |
| Paper Crafts | Thin layer of glue on paper surfaces; slightly more for cardstock or heavy materials |
| General Crafting | Enough glue to form a strong bond between the two materials; avoid excess glue |
By using the right amount of glue, you can ensure that your project is strong and secure without creating a mess or wasting any glue. Remember to always use a clean, dry surface and allow enough time for the glue to dry completely before handling or moving the project.
If you’re interested in learning more about glue, check out our article on food glue and how it’s used in the food industry.
Allowing Time for Drying
After applying PVA glue to a surface, it is important to allow adequate time for drying before moving or using the item. The drying time for PVA glue depends on the amount of glue used, the temperature and humidity of the environment, and the type of project involved.
To ensure proper drying time, it is helpful to follow the manufacturer’s instructions and recommendations. In general, PVA glue dries within 24 hours, but smaller projects may require less time. To be sure that the glue has dried completely, check if the surface is no longer tacky to the touch. Trying to move or handle the item before the glue is completely dry can result in the bond breaking or the item becoming misaligned.
Another important consideration when allowing time for drying is the environmental conditions. High humidity and low temperatures can slow down the drying process and may require additional drying time. Conversely, warm and dry conditions can speed up the drying process.
It is also a good idea to plan ahead and allow enough time for the glue to dry completely before starting to use the item. Rushing the drying process can lead to mistakes and ultimately damage or ruin the project.
In some cases, using a fan or heat source can aid in drying the glue faster, but again, it is important to follow the manufacturer’s instructions to avoid causing damage to the glue or the item being glued.
Properly allowing time for drying is a key aspect of using PVA glue effectively. Taking the time to ensure that the glue is completely dry will result in a strong and long-lasting bond.
Clean Up
When it comes to using PVA glue, one should not only pay attention to the stickiness but also to the clean-up process. Cleaning up after using PVA glue is important in order to maintain the quality of the materials and ensure that the surface looks clean and neat. PVA glue is water-soluble, which means it will dissolve easily in water. Cleaning up after using it is quite easy.
To clean up after applying PVA glue, one just needs water and a clean cloth. Wet the cloth with water and wipe away the excess glue from the surface following application. The cloth should be damp, but not soaking wet, otherwise, you risk disrupting the bond between the glue and surface. If the glue has already dried up, use a scraper or a blunt-edged tool to remove the glue from the surface.
It is also important to keep the tools used for applying PVA glue clean. This prevents glue from drying up on tools and restricts future use. Once done using the glue and tools, rinse them with water and leave them to dry completely before storage.
If you’re interested in learning about the history of glue, check out our article on how horses make glue.
Alternative Glues for Difficult Surfaces
When it comes to difficult surfaces, PVA glue may not always do the trick. Fortunately, there are alternative glue options available that can provide stronger adhesive properties where PVA falls short.
Epoxy: Epoxy is a two-part adhesive that consists of a hardener and a resin. When combined, they form a strong chemical bond that is resistant to water, heat, and chemicals. Epoxy glue is particularly useful for bonding metals, ceramics, and glass. However, it can be difficult to work with due to its fast-drying properties, so it is important to work quickly and precisely when using it.
Super Glue: Also known as cyanoacrylate glue, super glue is a quick-drying adhesive that bonds quickly and strongly to a variety of surfaces. It is particularly useful for bonding non-porous surfaces such as metal, plastic, and rubber. However, it can be brittle and may not hold up well under constant stress or strain.
Silicone Adhesive: Silicone adhesive is a versatile adhesive that can bond a wide variety of surfaces, including metal, glass, plastic, and rubber. It is known for its flexibility and resistance to high temperatures, making it useful for bonding materials that are subjected to heat or movement. Silicone adhesive is also resistant to UV radiation and weathering, making it a good choice for outdoor applications.
While these alternative glues can be effective for difficult surfaces, it is important to note that each has its own strengths and weaknesses. Consider the specific needs of your project when selecting a glue and be sure to follow the manufacturer’s instructions for best results.
If you want to know more about glue, check out why is glue bad at math to understand the reasoning behind this phenomenon, what glue conducts electricity to learn about conductive glue and its applications, or what rugby glue is to discover the unique adhesive used in the sport of rugby.
Epoxy
If you’re working on a project that involves difficult surfaces and you find that PVA glue just won’t do the trick, there are alternative options available. One of these is epoxy adhesive. Epoxy is known for its strong bonding properties, making it an excellent option for materials that PVA glue won’t stick to. But how does epoxy work, and when should you consider using it over other glues? Let’s take a closer look at this popular adhesive.
Super Glue
When it comes to difficult surfaces that PVA glue just won’t stick to, super glue may be the answer. Here are some benefits and drawbacks of using super glue:
Benefits:
- Super glue is known for its quick-drying ability, making it a great alternative to PVA glue for small projects or repairs.
- It can bond to a variety of surfaces, including plastics, metals, and ceramics.
- Super glue is water-resistant and can hold up well in humid environments.
Drawbacks:
- Super glue can be too strong for certain materials, causing them to break or crack when attempting to remove it.
- It can also be difficult to remove from skin, fabrics, and surfaces once it has dried.
- Unlike PVA glue, super glue is not ideal for larger projects or applications that require flexibility.
While super glue may be a good alternative to PVA glue for certain materials and projects, it is important to use it with caution and follow the manufacturer’s instructions carefully. It may also be wise to test it on a small area before applying it to the entire surface.
Silicone Adhesive
When PVA glue fails to stick to a particular surface, silicone adhesive can be a good alternative. This type of adhesive is especially resilient and remains flexible even after it dries, making it perfect for use on materials that may expand, contract, or experience vibration. It is also water-resistant, so it can be used to join objects that need to withstand water exposure.
Advantages of Silicone Adhesive:
- Silicone adhesive is suitable for use on a wide range of surfaces, including glass, metal, and plastic.
- It forms a strong and durable bond that remains flexible even after it dries, making it perfect for objects that move, expand, or contract.
- It is also resistant to water, so it can be used for outdoor applications or in moist environments.
Disadvantages of Silicone Adhesive:
- It is not suitable for use on surfaces that may be painted or finished, as the flexible properties of the adhesive can cause it to bleed through the paint or finish.
- It can take a long time to dry, which may be a disadvantage if you need a quick bond.
- Curing time can be affected by temperature and humidity, and if the adhesive is not given enough time to cure, the bond may fail.
Tips for Using Silicone Adhesive:
- Make sure the surfaces are clean and dry before applying the adhesive.
- Apply the adhesive evenly and avoid using too much, as excess adhesive can take longer to cure.
- Allow enough time for the adhesive to cure before subjecting the joined objects to stress or strain.
- Be mindful of the temperature and humidity when using silicone adhesive, as this can affect the curing time.
While PVA glue is a versatile adhesive, it may not work well on every surface. In such cases, silicone adhesive can be an excellent alternative. With the right preparation and application techniques, it can create a strong and durable bond that can last for a long time.
Conclusion
Wrap Up
In conclusion, PVA glue is a versatile adhesive that can bond a wide range of materials. However, it is important to understand the surfaces it may not adhere to and how to use it effectively. Remember that PVA glue may not stick to plastic, greasy or oily surfaces, metals, glass, wax or soap-based products, or wet surfaces. Prep the surface properly, use the right amount of glue, and allow enough time for drying to make the most out of PVA glue.
If you find that PVA glue is not suitable for your project, consider using alternative adhesives such as epoxy, super glue, or silicone adhesive. Each of these has its own unique strengths and weaknesses, so be sure to choose the one that best fits your needs.
With a little patience and understanding of how PVA glue works, you can achieve strong and durable bonds on all kinds of materials. Happy crafting!
Frequently Asked Questions
Can PVA glue be used on plastic surfaces?
No, PVA glue does not stick to plastic surfaces as it cannot adhere to the smooth and non-porous surfaces of plastic.
Can PVA glue be used on metal surfaces?
No, PVA glue does not work well on metal surfaces as it cannot withstand the strength and durability required for metal bonding.
Does PVA glue work on wet surfaces?
No, PVA glue does not stick well to wet surfaces. The surface needs to be dry and free of moisture for proper adhesion.
Can PVA glue be used to bond glass surfaces?
No, PVA glue is not recommended for bonding glass surfaces due to its inability to adhere to non-porous surfaces like glass.
How much PVA glue should be used for effective adhesion?
It is recommended to use a thin, even layer of PVA glue for effective adhesion. Using too much glue can cause the bond to weaken over time.
How long does PVA glue take to dry?
The drying time of PVA glue varies depending on the amount of glue used and the humidity level of the environment. Generally, it takes around 24 hours for PVA glue to fully dry.
Can PVA glue be painted over?
Yes, PVA glue can be painted over once it has fully dried. However, it is recommended to test a small area first to ensure the final result is as desired.
What surfaces can PVA glue bond effectively?
PVA glue can bond well to porous surfaces such as paper, wood, and fabric.
What is the difference between PVA glue and epoxy glue?
PVA glue is a water-based adhesive and is best suited for porous surfaces. Epoxy glue is a more durable and waterproof adhesive that works well on non-porous surfaces such as metal and plastic.
What are some tips for cleaning up PVA glue?
It’s best to remove excess glue immediately with a damp cloth. If the glue has dried, it can be removed with warm soapy water or vinegar.