- Shelf Life & Storage
- Suitable Surfaces
- Temperature Effects
- Surface Preparation
- How to Remove Adhesive
Permabond has over 50 years of adhesives experience. During this time, we've amassed considerable knowledge and expertise regarding the application, handling and storage of adhesives. With this knowledge, Permabond has become a uniquely capable resource for communicating the positive affects Permabond products have in many areas around the globe. Recognizing the significance of this responsibility, we have produced this section to serve as an introduction to the most common considerations regarding the proper utilization of our products:
Shelf Life & Storage
Proper Adhesive Storage Means Greater Profits
Over the lifetime of an application, you may significantly reduce your adhesive usage by paying close attention to the adhesive shelf life and storage conditions recommended by Permabond. Because of the various chemistries involved in the adhesives that Permabond manufacturers, we have developed specific storage condition recommendations by product.
These recommendations should be reviewed prior to selecting an adhesive for your application and should be followed whenever possible. The shelf life of each Permabond adhesive is based on our experience with that product under controlled conditions.
Therefore, we are certain that these adhesives when stored per our guidelines will maintain their performance over the course of the shelf life given. Unfortunately, if the adhesive has not been stored according to the recommendations given we often have no information as to how it will perform.
Adhesive Shelf Life
The shelf life of a product is the time it may be stored under specified conditions with no significant changes in properties. It is recommended that each adhesive family be stored under its specific conditions. Many adhesives are sensitive to extreme temperatures and some to light and humidity exposure.
Generally, Permabond recommends that each adhesive type be stored within the temperatures indicated below. Please contact Permabond’s technical team for the specific product information you require.
Store Permabond anaerobic adhesives and sealants in the unopened container at 5-25°C (41-77°F).
For maximum shelf life of Permabond cyanoacrylate adhesives, store unopened cyanoacrylate at 2°C (35°F) to 7°C (45°F). Unopened cyanoacrylate products should be brought to ambient temperature before the package is opened. Once opened, the package should be left at ambient temperature. Storage below 2°C (36°F) or greater than 8°C (46°F) can adversely affect product properties.
Permabond ET Two Part Epoxy
Store Permabond two part epoxies at between 5-25°C (41-77°F) in their original unopened package.
Permabond ES One Part Epoxy
Store Permabond one part epoxies at between 2°C – 7°C (35°F – 45°F), in their original unopened package.
Permabond MS MS Polymers
Store Permabond MS polymers in the original unopened container between 10°C to 25°C (50°F to 77°F)
Permabond PT Two Part Polyurethane
Store Permabond polyurethane adhesives in the original unopened container between 15°C to 25°C (59°F to 77°F) Store cartridges inverted.
Permabond Structural Acrylics
Store Permabond structural acrylic adhesives in the original unopened container between 5-25°C (41-77°F)
Permabond UV Curable Adhesives
Store Permabond UV curable adhesives in the original unopened container between 5-25°C (41-77°F)
Common Surfaces and their Suitability for Adhesive Bonding
A critical factor in the success of any adhesive bond is the condition of the assembly surfaces being joined. Every assembly surface has unique characteristics, either inherent in its material make up, such as aluminium oxidation; or added to it during manufacturing, such as rust inhibitors. This guide provides an overview of several common materials and their suitability for adhesive bonding. Consult a Permabond representative for a complete assessment of your assembly surfaces and determination of the best Permabond adhesive for your specific application.
Aluminium and its Alloys
Surface appears clean but has a thin oxide film that weakens the bond between the true aluminium surface and the adhesive. Some oxide films may be stable enough to provide a strong bond without any surface preparation. Aluminium is the exception. Permabond can help you evaluate your aluminium and advise which method of pre-treatment would be most appropriate to optimize bond performance. Oxide films form immediately, even after surface treatment. Surface bonding must take place as soon as possible to achieve maximum adhesion strength.
Conventional Steel Alloys
Mild steel alloys typically present surfaces readily able to be bonded.
Presents an oxide film that may weaken the bond between the true steel and the adhesive. Zinc plating may separate from the steel surface as a result of the adhesive. May require chemical treatment to eliminate the zinc separation from the steel sheet.
Treated Zinc-plated Steel
The treated surface is both unsuitable and unreliable for adhesive bonding. Certain chemical treatment methods can present workable bonding surfaces. Consult with a Permabond representative to evaluate treated zinc-plated steel surface bonding applications.
Structural joints cannot be formed on PVC clad surfaces of mild steel. Cyanoacrylate adhesives will provide good adhesion to the PVC surface.
Painted Steel Panels
Structural joints cannot be formed on the painted surfaces of steel panels. Several Permabond adhesives will provide good adhesion to painted steel panels. Maximum adhesion will be achieved by those Permabond adhesives that will flex with the bending of thin sheet panels.
Stainless Steel Alloys
Depending on the application, chemical surface treatment may be necessary. Surface preparation with abrasion and a solvent wipe is suitable in most cases.
Permabond cyanoacrylate adhesives bond well to these surfaces. Surface activated toughed acrylics may not provide suitable gap filling ability for large structural applications.
Acrylic-faced Thermoset GRPs
Structural joints cannot be formed on the acrylic face of these surfaces. Permabond cyanoacrylate adhesives will provide the maximum adhesion to the acrylic faced surface. The cyanoacrylate adhesive, in its liquid form, will cause stress cracking on the acrylic face after prolonged exposure. Use a Permabond cyanoacrylate activator to accelerate cure and minimize exposure to uncured adhesive.
Wood-faced Thermoset GRPs
Wood-faced Thermoset GRPs typically present surfaces readily able to be bonded. Several Permabond adhesives will provide good adhesion to these surfaces. Consult with a Permabond representative to evaluate wood-faced thermoset GRP surface bonding adhesives.
These structural composites, typically epoxy-based, bond well with a variety of Permabond adhesives.
Permabond cyanoacrylate adhesive will provide good adhesion to these surfaces. The adhesive, in its liquid form, will cause stress cracking on the surface after prolonged exposure.
Extensive surface treatment may be necessary to achieve suitable bonding. Consult with a Permabond representative to evaluate nylon-faced surface bonding applications.
Extensive surface treatment may be necessary to achieve suitable bonding. Consult with a Permabond representative to evaluate polyolefin-faced surface bonding applications. Permabond POP primer can be used to treat polyolefins before bonding with cyanoacrylate adhesive.
Presents a difficult surface for effective adhesive bonding. Consult with a Permabond representative to evaluate polyurethane-faced surface bonding applications.
Permabond cyanoacrylate adhesives will provide a suitable bond to both rigid and flexible PVC surfaces.
Controlling Cure Rates and Production Speed
Many environmental conditions affect how adhesives cure and perform over long periods of time. One of the most significant environmental factors is temperature. Minor changes in temperature can have major changes in cure speed and storage life of adhesives. Most organic adhesives have maximum continuous operating temperatures and if exposed to higher temperatures for long periods of time their performance drops significantly. Permabond has put together some guidelines for your reference to eliminate or control the potential impact of temperature and other environmental conditions on your application.
Effect of Environmental Temperature
The temperature at which the adhesive is being applied and used will affect its cure. All cure times quoted in Permabond Technical Data Sheets are taken at 23°C.
The anaerobic sealants are affected by a rise or fall in the temperature of the area in which they are being used. The general rule is for every 8°C (15°F) that the temperature increases; the time required for the adhesive to cure will be halved. Conversely, if the temperature is 8°C (15°F) cooler the cure time will double.
Cyanoacrylates cure using surface moisture and are less affected by temperature. However, the humidity and the type of surface being bonded can affect cyanoacrylates.
Permabond’s adhesives are organic in their chemistry and, as such, generally have service temperature ranges between -80°C to 250°C (-60°F to 482°F). Please refer to the Technical Data Sheet for the specific product grade features including the temperature range.
Common Surface Preparation Guidelines
Although many of Permabond’s industrial adhesives provide excellent bonding to “as received” surfaces, proper surface preparation will dramatically improve adhesion strength and bond performance. A properly prepared component will present a surface that is uniformly clean, mechanically sound, and correctly textured. A prepared surface will ensure strong and durable bonds; particularly when harsh usage environments are present. This guide provides an overview of several surface preparation methods. Consult a Permabond representative for a complete assessment of your assembly surfaces and determination of the best surface preparation method for your specific application.
Surface Preparation – Solvents
If possible, remove surface oil or grease with an aqueous-based cleanser. If aqueous-based cleansers are ineffective, isopropyl alcohol is recommended. If isopropyl alcohol is ineffective, solvents such as acetone or methyl ethyl ketone can be used. It is recommended that the surface material first be tested as certain thermoplastics may crack or dissolve when reacting to various solvents.
Surface Preparation – Mechanical
Mechanical abrasion is a process of slightly roughening the surface of the component to be bonded. The surface roughness should be kept to less than 0.1 microns (0.004 millimeters) to reduce the possibility of small contaminants or air bubbles becoming trapped in the roughened surface and degrading the bond performance. Scarification is typically done with either an abrasion or a blasting process.
Surface Preparation – Abrasion
Abrade using 45 to 106 micron grit or a three-dimensional, non-woven abrasive fabric. Abrading can be done as either a wet or a dry process. If doing wet abrading, use only media designated as water-resistant. When preparing aluminium surfaces always use the wet method to prevent the oxide pores from clogging with abraded contaminants. Proper surface condition has been achieved when the surface can be immersed in clean water, and when removed a water film remains unbroken for 30 seconds. Do not use iron- or steel-based grits on aluminium, copper, or stainless steel components.
Surface Preparation – Dry Blasting
Typically used on metallic components. May also be used on heavy-duty plastics. Blast using 45 to 106 micron grit until the surface is uniform in cleanliness and texture.
Surface Preparation – Wet Blasting
Typically used on small metallic components. Blast using 1000 mesh grit suspended in either water or steam. In the event a system uses water-soluble additives, consult the system manufacturer to eliminate contamination of the surface by the additives.
Surface Preparation: Non-mechanical
Non-mechanical surface preparation methods are typically for only high volume plastic or composite component production applications. Non-mechanical surface preparation modifies the chemical characteristics of the component’s surface to an optimum condition for adhesive bonding. Gas Flame Oxidizing: Economical and effective method of preparing plastic or composite surfaces. Rapidly adapts to changes in component topography.
Surface Preparation – Plasma Discharge
Also known as Corona Discharge. Economical and effective method of preparing plastic or composite surfaces. Best suited for components with simple, or flat topography.
Surface Preparation – Plasma Chamber
Utilizes a discharge chamber to process large volume component batches. Best suited for batches with complex, or multiple component shapes. Requires greater initial capital investment; provides greater volume and part type processing than other non-mechanical surface preparation processes.
Surface Preparation – Laser
Can be used for metal and plastic component surfaces. Requires extensive system design, and calibration. Consult with a Permabond representative to evaluate laser surface preparation for your application.
How to Remove Adhesive
The three primary means to remove adhesive that has already been cured are:
Depending on the type of adhesive and the substrates or assembly in question, the easiest way to remove adhesive that has been cured can be chosen.
For example, if trying to degrade a cyanoacrylate bond, keep in mind that they are brittle and often don’t have much peel strength. Also, they have poor resistance to polar solvents such as water. Warm soapy water works faster!
If you want to get an epoxy bond to fail, water isn’t going to help much. High temperature may be a better option. Many two component epoxies will fail at or below 200°F. If using heat to destroy a single component epoxy bond – raise that to 400°F.
Remove Adhesive – by Adhesive Type
Anaerobic Threadlockers: These are available in a range of strengths. The low strength products can easily be undone with tools such as spanners or wrenches. For high strength permanent threadlocking adhesives, using heavy duty tools can result in shearing the bolt that you are trying to undo. If you have used a threadlocker on a large diameter bolt and/or it has a long engagement, even if you have used a low strength “dismantleable” product, it may be very difficult to undo due to the large bond area.
Anaerobic Gasketmakers: Placing a flat-bladed screwdriver or similar implement and hitting it with a hammer to prize the components apart should be enough to pop the gasket. Anaerobic adhesives are excellent in tensile shear or compression but weak under peel or cleavage stress. Once the components are separated remove adhesive by scraping or brushing with a wire brush.
Anaerobic Thread Sealants aka Pipe Sealants: Normally these are low strength products which can be undone with a suitably sized wrench. Like the threadlockers, if used on large diameter or long engagement pipes these could prove more difficult to undo.
Anaerobic Retaining Compounds: Retaining compounds are actually for permanent bonding of bearings, housings, shafts, keyways and other concentric joints. They are typically very high strength and impossible to remove without using heat or chemicals.
Removing a stubborn Anaerobic Adhesive: By heating the bond area with a blow-torch, or placing the item in an oven to heat up will help weaken the adhesive. Attempt adhesive de-bonding while the parts are as hot as possible (once they cool back down the original strength will come back!). You will require oven or foundry gloves to hold the parts. Once components have been successfully dissembled, clean thoroughly before re-bonding. A wire brush, wire wool, wet and dry paper are all good for removing cured anaerobic (which often appears as a white-coloured powdery solid). Wipe down with acetone. Stubborn cured lumps will come off after soaking in an aggressive solvent such as acetone or methylene chloride. Parts which refuse to come apart can be soaked in such solvents overnight, and the disassembly process attempted the next morning. NOTE be certain that no solvent residue is present on the parts and the solvent container has been removed from the work area prior to using the blowtorch.
Always store the solvent in tins with the lid on in a flame proof cabinet.
These recommendations assume all component parts are metal.
Cyanoacrylate Instant Adhesives: Removing the adhesive is more difficult, as often they are used to bond plastics and rubber which will not withstand high temperatures or aggressive solvents. These adhesives are fairly brittle so pulling parts apart with a peeling motion will make the bond easier to break. If possible heat the parts to above 80°C (the point at which most cyanoacrylates lose a lot of strength) and then attempt to pull apart. If parts are metal and not delicate, they can be subjected to more extreme heat or solvent soaking in acetone or methylene chloride. Skin bonded with cyanoacrylate will need to be soaked in hot soapy water; stuck fingers can be prised apart by rolling a pencil gently between the fingers. It is not recommended to use solvent on hands as it will de-fat the skin. Soapy water is not only good to remove adhesive from skin, if your components can take a nice long bath, they will de-bond over time. To shorten the time use hot water.
Epoxy, Polyurethane, Structural Acrylic Adhesives: These types of high strength adhesives can be tricky to de-bond. Certain products have both high shear and peel strengths so trying to peel parts apart may not work. Check the maximum operating temperature of the adhesive and assess if you can heat the component parts above this temperature to attempt disassembly. Most 2-part epoxies, acrylics, and PUs will start to degrade permanently at 200°C. Single part epoxies will need to be taken even higher. Methylene chloride can be used to remove cured adhesive, but if you have a large or complex joint, it will only “eat” into the edges very slowly.
UV Cure Adhesives: Extra care needs to be taken as substrates are typically glass and cannot be peeled, whacked or levered of course! The heating method of adhesive de-bonding could be a problem if the substrate materials are glass to metal as differential thermal expansion and contraction could cause glass cracking. However, glass to glass you could heat to the point the adhesive degrades permanently (>200°C). Glass to metal can be soaked in solvent as per other adhesive types. Plastics which have been bonded with UV adhesive such as polycarbonate or acrylic will be attacked by solvent. Even if you manage to get the components apart, removing cured adhesive will be a problem. Check the water absorption rates with the manufacturer; some products will absorb water. Boiling the parts in water may allow the adhesive to absorb enough water to soften it. Complete the removal while the adhesive is still wet as upon drying the strength will return.
Please contact Permabond for information on how to remove the toughest bonds.