Frequently Asked Questions
Find answers to our most commonly asked questions about engineering adhesives below. And please reach out to our technical support team if you have any additional questions.
How strong are your adhesives?
In most cases, we aim to have the substrate you are bonding fail before the adhesive. To give you an idea of how strong they can be, our adhesives have been used on bridges and F1 cars. Good joint design, proper surface preparation, as well as the substrates you are bonding all play a role in bond strength. To learn more about the strongest adhesives for metal, plastic, glass, composites and more, see this article.
How much adhesive do I need to use?
What bond line thickness do you recommend?
How do I buy your products?
Which types of adhesive do you sell?
Which adhesive do I need for my application?
- What is the finished item?
- What are the substrate materials you wish to bond?
- What is the size of the bond area?
- What size gap do you need to fill, or are you looking for a coating?
- What are the environmental conditions (temperature/chemical exposure)?
- In what timeframe do you need the adhesive to cure?
- Is color important? If so, please state preference.
Are there any types of adhesive that you don’t sell?
Here are various type of adhesive we do not currently manufacture:
- Solvent (including water) based adhesives
- Contact adhesives
- Silicone adhesives
- Tapes
- Single-part polyurethanes
- Adhesives that can withstand over 300°C
Where can I find technical advice/suggestions?
What are the maximum and minimum temperatures that your adhesives are able to withstand?
How should I store my adhesives?
Do you sell dispensing equipment?
How many nozzles do you supply per cartridge?
What do you mean by viscosity? What are high and low viscosity adhesives?
What do you mean by ‘thixotropic’? What is a thixotropic adhesive?
Which wavelength do I need to bond/activate Permabond UV adhesives?
Why should I use Permabond over other adhesive manufacturers?
Does the Tg of an adhesive need to match the maximum temperature of my application?
Why doesn’t Permabond have CE markings on product labels?
Why can’t I have a declaration from Permabond confirming that its products meet EU MDR (European Union Medical Device Regulation)?
What is Epoxy Resin Crystallization?
Signs of Crystallization
Crystallization manifests as cloudiness, free-floating crystals, crystal masses, or complete solidification. Initially, the clear resin becomes foggy, cloudy, or hazy, and instead of being smooth, starts to gain a grainy texture. White sedimentation may gradually accumulate, typically starting from the bottom or sides of the container, eventually spreading throughout its contents. Once fully solidified, crystallized epoxy resin can remain in this state indefinitely.Causes of Crystallization
Crystallization can occur unpredictably and may affect different containers within the same production batch to varying degrees. Factors contributing to crystallization include resin purity, viscosity, additives, moisture content, and temperature history, such as exposure to extreme cold or thermal cycling.High Purity
Highly pure resins are more prone to crystallization compared to impure ones. Narrow molecular weight distributions indicate high purity, while broader distributions suggest impurities. The addition of anti-freeze or high molecular weight oligomers/isomers can hinder crystallization but poses formulation challenges.Low Viscosity
Lower viscosity resins, particularly when combined with reactive diluents, crystallize faster than higher viscosity ones. Temperature reduction decreases molecular motion, slowing crystallization. However, storing resin at 0°C may inadvertently promote crystallization due to hidden seed crystals.Additives – Solid Fillers
Solid fillers like precipitated calcium carbonate, alumina, silica, or even scratches on container surfaces can act as seeds for crystal growth, accelerating crystallization.Temperature and Thermal Cycles
Cold temperatures slow crystal formation by increasing viscosity, but extreme cold accelerates growth once seed crystals form. Temperature fluctuations, even of as little as 20-30°C, are a very common cause of crystallization, especially during day-night cycles.Solutions
Crystallization tends to be more of an inconvenience than a real problem. Re-melting crystals by heating resin to 50°C for several hours effectively reverses crystallization. It’s crucial to ensure complete melting of all crystals, preventing them from acting as seeds, before cooling to room temperature. Carefully inspect the container’s sides, bottom, and areas around the caps for any signs of crystallization that could initiate further growth. Whenever possible, it’s advisable to clean bottle caps, bottle necks, spigots, spouts, pumps, piping, and valves with a solvent such as isopropyl alcohol (IPA) or acetone after each use to prevent seed development. Monitoring and controlling shipping and storage temperatures effectively prevent crystallization due to temperature fluctuations. Good housekeeping practices also play a significant role in preventing crystallization. Important Note: Re-melting of crystals should exclusively be performed on the resin side (part A) of the epoxy. In rare instances, warming a part B or single-component system might be necessary. Please consult our Technical Experts for specific heating recommendations. It’s important to refrain from using this technique with pre-mixed and frozen systems, as it could lead to premature curing or cross-linking. To summarise in brief: – Epoxy crystallisation is a common phenomenon – It is easily reversed by heating resin at 50 deg. C for 2-3 hours – Strength and performance properties of the adhesive should remain unchanged after crystal re-melting process.
What do the warning/hazard symbols on adhesive labels mean?

Which hazard symbols are common on adhesive labels and how do I use the adhesive safely?
GHS 07 is the most commonly seen hazard symbol on adhesive labels. Denoting an irritant, products with this label can easily irritate and/or damage the skin, eyes and respiratory tract. Gloves and protective eyewear should be worn as standard when using such an adhesive. Also important as a general rule is good ventilation and extraction in the workspace, which will allow any adhesive fumes to be dispersed and taken away from the immediate working environment. As an extra safety precaution, masks can be worn when working with these products. This hazard symbol is commonly seen across all adhesive chemistries, including cyanoacrylates, anaerobics, epoxies and UV light curing adhesives.
GHS 05, denoting a corrosive substance, is found on some Permabond anaerobic and structural acrylic adhesives, and on many B parts of two-part epoxies and UV adhesives. Extra care must be taken when working with an adhesive that is corrosive, as these can easily cause skin burns, as well as being corrosive to metals. The easiest way to avoid any damage from these products is to always wear gloves, protective clothing and eyewear, as well as a mask during their handling and use.
GHS 02, denoting a flammable substance, can be found on some Permabond structural acrylic adhesives. The key to safe usage of these products lies in keeping them well away from all sources of fire and ignition. Make sure that the lid is always put securely back on the product once it is no longer in use. These products are usually stored cold, in order to keep them below flash points as well as to ensure a longer shelf life.
GHS 08 is the most worrisome hazard symbol that you might find on an adhesive label or SDS. Denoting a serious health hazard, a product with this symbol is dangerous to health if breathed in or ingested. Pregnant women and people who are frail or otherwise in poor health should ideally avoid using these products, and of course, those who do use them need to make sure they are fully protected with PPE. In the UK, employers must prevent or adequately control exposures to hazardous substances, a requirement of the Control of Substances Hazardous to Health (COSHH) Regulations Act. To this end, Local Exhaust Ventilation (LEV) needs to be installed where dangerous particles such as dust, mists, gases and vapours are produced, in order to take them out of the air and keep workers safe. Extra care needs to be taken to make sure these adhesives are properly sealed and stored after use.
GHS 09, denoting a product that is harmful to the environment and specifically aquatic life, can be found on many Permabond epoxy adhesives (both single and two-part), as well as on UV adhesives’ SDSs. Adhesives bearing this symbol can release harmful chemicals into the soil, water and air, which can negatively affect wildlife and plants. The key thing to bear in mind here is proper waste disposal. Make sure that all used glue containers are properly sealed before disposal to prevent any remaining adhesive from seeping out. It is illegal to simply throw empty adhesive cartridges into a skip or normal plastic waste bins – these are hazardous products and must be treated as such. In many cases, it is easier to hire a hazardous waste disposal company to come and collect your used cartridges in order to comply with the law and avoid fines.
A general adhesive health and safety concern is that of complacency, especially in those who are frequent users of glues. Working day in, day out with adhesives can cause someone to become less vigilant about their potential harmful effects, leading to a slackening in the proper health and safety care being taken. Eventually, this could result in skin conditions such as dermatitis/eczema, or breathing issues such as asthma arising. If this were to occur, the affected person should not handle this particular chemical again and make sure that, when handling adhesives of a different chemistry, that proper health and safety precautions are taken and continue to be upheld.
What is REACH?
What are SVHCs and why do they matter?
Part of the scope of REACH is determining Substances of Very High Concern (SVHCs). This is a list of substances that have been proposed for inclusion on the Authorisation List of REACH. Companies selling to/within Europe who wish to sell products on this list need to apply for authorization from the European Commission to do so.
SVHCs are generally substances which have been deemed by scientists to be carcinogenic, mutagenic (having the ability to permanently alter someone’s DNA), harmful to fertility and/or offspring, or persistent (meaning resistant to biological breakdown), bioaccumulative and toxic (BPT substances). There are other criteria apart from these, but any substance deemed to have met at least one of the above is liable to be defined as an SVHC.
These substances pose a problem for adhesives manufacturers, since the SVHC list gets updated twice a year and new substances are therefore constantly being added which were not previously present.
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