FAQs

There are two extremes to be avoided – heat and cold. We recommend that you store your adhesives out of direct sunlight in a dry area at a temperature between 5 and 30 Celsius. Adhesives must also be protected from freezing as this will cause damage. For optimum performance, store water based adhesives at temperatures between 15 and 25 Celsius, and never outside.

Bulk storage systems can be useful, but we would need to know more before giving a definitive answer. An annual usage of 100 tonne of adhesive per year is usually the minimum for the best use of a bulk storage system.
The practicality may also depend on the number of different machines and applications you are running. We can advise on your individual requirements and help advise on tanks, pumping, metering and distribution systems through an engineering provider who specialises in bulk storage systems for adhesives.

We conduct life-time studies on all of our water-based PVA adhesives and all containers are shipped with a best before date on the label. Most of our hot melt adhesives are given a two year shelf life but may be extended depending on storage conditions. Do get in touch if you need more advice. We cannot guarantee the performance of our adhesives once they’ve passed their best before date.

Our water-based products can be diluted with water, provided that they are fully mixed. However, we do not recommend mixing different adhesive grades, as they may be incompatible, causing blocked systems. If you suspect your current adhesive is too thick, please contact us for advice. It is very likely that we can supply a thinner version from our range to better suit your specific needs.

Our water-based adhesives are not subject to ADR regulations and so there are no restrictions on road or rail transport.
Transporting water-based adhesives by are can cause problems. Often the aircraft hold is unheated and at high altitude the low temperatures can cause damage to the adhesive. Make sure the adhesive is stored between 5 to 30 Celsius.

Adhesive application machinery is running at ever faster speeds, creating the need to ensure the right adhesive is used to optimise machine outputs and reduce down-time for cleaning.
From our in house laboratory we carefully formulate and test our adhesives for maximum machine performance. Our products are designed to run clean at high speeds.

It is possible that you are over-filling the wheel reservoir which can lead to adhesive coming into contact with the side of the wheel above the scraper blade. We would recommend reducing the level in the reservoir by either lowering the spout of the feed bottle, or reducing the pumping rate from your storage tank Alternatively, if you have a height sensor fitted, move this to a lower position.

Applicator nozzles and jets may become blocked when adhesive dries on the top or the adhesive had not been sieved properly. Glue drying on the tip can cause the adhesive to block the nozzle completely. It is essential that you keep your machines well maintained and regularly cleaned.
Our specialists can formulate an adhesive that does not dry on the tip and will reduce machine down time.

Glue jetting equipment is designed to be able to spray even the thinnest of liquids – even pure water – without dripping. A dripping nozzle is commonly caused by poor maintenance and may require seals and/or nozzle tips to be replaced. In rare cases, it can be caused by debris trapped in the nozzle tip. If this persists, after maintenance, it indicates that a more appropriate adhesive should be considered.

Tubes covered with a high-quality label can often show the spiral join. There are a number of actions that can be taken to reduce this effect. It could be because your board is swelling. One solution is to make sure you are using the right grade of adhesive to reduce board swelling. Please get in touch with a member of our team to see how we could help resolve this issue.

If fishtailing occurs, make sure your squaring unit is operating correctly. If it is, the problem is most probably due to bonding speed. Try applying less adhesive. If this does not solve the problem, please call Pafra Adhesives for a faster adhesive.

The strength of the overlap hold-down is dependent on two factors; the cover material and the adhesive type. OPP laminates are the most difficult to bond. A high level of corona treatment to the OPP will help and an adhesive designed for this material will improve the final bond.

Some perfect binders are difficult to set so that both long and short folds are held down properly. Perfect binding machine needs an adhesive with long open times and high grab properties. We have a range of glues suitable for all types of perfect binding machines.

Some envelope-making machines bend the envelope immediately after the window has been glued. At high speeds the windows do not have enough time to bond properly. We have developed an adhesive especially for high-speed window patching.

Curl in laminated products is caused by unequal expansion and shrinkage of the different layers. Reverse stacking can help to counteract curl. Alternatively, Pafra Adhesives can supply special low-curl laminating adhesives.

Apply the minimum adhesive that still gives a good bond. If there is still a problem; contact Pafra Adhesives Technical services for advice.

If you are having difficulty getting good front-to-back register when laminating reel-to-reel; it could be that your adhesive is too slow.

You could try a lower adhesive coat weight or use a faster setting adhesive if your production is too slow, when laminating. We have an in-house laboratory that has developed clean running, fast-setting adhesives that can solve this problem.

If you make bags and find that the bottom seal fails during folding, you could try to solve the problem by running slightly more adhesive – it needs to be tacky at this point. The downside is that this will increase the cost of production as you’ll be using more adhesive.

Cobwebbing is normally caused by one of two problems – either the running temperature is too low or the machine is running at high speeds. The solution is to make sure the tank/hose/nozzle temperatures are correct and consider increasing. Usually these are set at increasing 5 °C increments. Alternatively Pafra Adhesives has developed a range of clean running packaging grade adhesives suitable for bonding at high line-speeds.

Melting rate is affected by several factors including your machine, the environment and adhesive selection. We recommend keeping the bath topped-up little and often rather than letting it run too low. Pafra Adhesives can advise other ways to improve your productivity. Please call us on 01268 290 610 for more information.

There may be a number of possible factors that have contributed to this type of failure. Possible solutions may involve using an adhesive that allows a longer open-time, a higher specific adhesion, adhesive alignment or incorrect adhesive selection.

If you find that hot-melt bonds fail at the end of your production line, it’s possible that the adhesive being used is not setting fast enough, causing cohesive failure. We have a range of packaging hot melt adhesives specifically designed for packaging, covering a range of setting speeds and application requirements for most end of line packaging requirements. Please call our technical team on 01268 290 610 to see how we can help.

Using an incorrect grade can cause cartons to ‘pop open’ during the microwave process. If this happens with your packaging, please call us on 01268 290 610. We have a range of food-safe adhesives for carton side-seam that are suitable for packages that will be used in a microwave oven.

A common problem with cartons for use in freezers is that the cartons can ‘pop open’. This happens when the adhesive becomes brittle at low temperatures. If this occurs with your packaging, you are using the wrong grade of adhesive. We have created a range of carton side-seam grades that are suitable for cartons that will be placed into a refrigerator or freezer. Please call us on 01268 290 610 for more information.

One of the challenges for the food packaging industry is bonding difficult surfaces that require chilled storage. Our laboratory has developed a range of food safe adhesives suitable for applications involving combinations of substrates to be used in chillers and freezers.

UV varnishes can be difficult to bond, requiring higher levels of adhesive. This is because UV varnish does not absorb water. As there is only one absorbent surface, line speeds have to be reduced to achieve good adhesion. Applying paper labels to PE bottle sometimes causes patches of un-bonded areas.This is usually an equipment issue, assuming you are applying the correct amount of adhesive over the whole label.

Should you find that bottle labels curl, it is probably that the labels have been cut in the wrong direction. You should discuss this with your printer or you could use a faster setting adhesive.

Many grades of adhesive will not bond a carton with a PE coating. The PE board is more difficult to bond than plain board as it has a lower surface energy, but a fibre-tear bond can be achieved by using a high adhesion grade adhesive. Fibre-tear development is slower on PE-coated boards than plain board due to the non-absorbent PE surface. Plastic windows can be bonded to PE-coated board but this requires a specialist adhesive. A full 24 hours is required to achieve maximum bonding performance as neither side is absorbent.

If your adhesive ‘cracks off’ (sometimes known as crystallising) when the bond is opened, it is a sign of poor adhesion. This is because the adhesive grade used does not bond the surfaces i.e the adhesive is not suitable for the job. A higher adhesion grade is required that is still suitable for the end use and application. Some boards have a clay coating to improve ink acceptance and general appearance. If the bond is opened and there is a white layer on each surface, the failure is not in the adhesive layer but within the clay coat. When the clay coating is thick and has been applied in several layers it is possible that this will separate. Our scientists have developed an adhesive that will prevent clay-coat stripping. Please call us for more details.

Pafra Adhesives has a range of peelable / fugitive adhesives suitable for a wide range of applications. These applications include for very weak substrates where conventional peelable grades give fibre-tear to grades suitable for pressure jetting systems. Hot melt peelable products are available when water-based products are not suitable.

Peelable adhesives are very sensitive to changes in the surfaces they bond and to the amount of adhesive applied. It is possible that the coat weight applied has increased over time. Alternatively the ink and/or varnish on the paper has changed, or may be variable. A minimum-sized spot of adhesive and low absorbency paper is recommended.

Water-based adhesives can thicken on water loss through evaporation. The extent of thickening depends on the grade and ambient conditions of temperature and humidity. Viscosity also changes with temperature. We recommend that you keep the lid on your storage tank at all times to prevent evaporation and check the temperature of the adhesive. Ensure that the temperature of the adhesive cannot go too low by insulating your storage tank or locating it in a warmer area of your factory.

All adhesive emulsions develop a skin over time. It is not a problem provided the skin does not become detached from the tray sides. The skin actually helps to reduce the of the adhesive below the skin thickening.

Adhesion failure on one side of a laminated sheet and not the other may be caused by a number of factors. The most likely is an uneven adhesive coat-weight across the sheet. The higher coat weight areas will give slower fibre-tear development than the areas of lower coat weight. The solution is to adjust the rollers and/or check the roller bearings for wear. Less likely causes are variations in water content across the virgin board or variations in board thickness. This can be a problem with some boards.

If nothing in your system has been changed and you are finding differences in you adhesive, there are a number of things to confirm. First, check the temperature of the adhesive on the machine. A bearing may have failed on the roller, causing friction and consequently a rise in the adhesive temperature. If your adhesive is fed to the roller via a flat tray, try to minimise airflow across the surface of the adhesive. The best way is to fit a lid to the tray if this is practical. You should also check to see if there is a heat source or fan near the machine that directs heat and/or airflow across the adhesive. If possible, this should be moved.

There could be a number of reasons for failures where nothing appears to have changed: including substrates, surface contamination and temperature. If this is something you have experienced, please contact Pafra Adhesives Technical Team for some practical advice.

If you find excessive bubbles in set hot-melt adhesive, this could be the result of too much moisture in the carton board when bonded. Ensure that materials to be bonded are stored in suitable cool, dry conditions.