Surface preparation for adhesives and best working practice

It is vitally important to ensure the maximum performance of the adhesive or tape is achieved, so we have put together this ‘best working practice’ for adhesive surface preparation.

It is always advisable to bond materials together in ambient temperatures i.e. between 15°C and 25°C . The first task before bonding your substrates is surface preparation, follow the guide below to ensure an optimum performance:

After selecting the correct adhesive, surface preparation is the most important thing you can do to achieve sufficient bond. This is because adhesives adhere to surfaces, and surfaces are often covered with dust, dirt, grease, oil, oxide films, rust inhibitors, and in the case of plastics, mould release agents. All these contaminants, even at a microscopic level, interfere with the adhesive doing its job. In fact, poor surface prep is the number one reason for bond failure.

For the strongest and most durable bonds, the goal is to apply adhesive to the substrate itself. However, often there are layers of surface contaminants that obstruct the surface. The ‘loose’ layer is all dust, dirt, and other loose particles. Beneath the loose layer lies surface oils and grease. Finally, there is sometimes an embedded layer clinging firmly to the surface such as rust, other oxide films, rust inhibitors, additives that have migrated to the surface such as mould release agents, and surface coatings like paint and sealants. All of the aforementioned prevent a strong bond, which is why surface preparation is so important.

How much surface preparation do I need?

Below are our recommendations for preparing surfaces for adhesive bonding. Please note that all manufactured materials vary significantly, even within the same type, as a result of different additives and methods used in the manufacturing process. This is especially true for plastics. Always test first on samples to determine suitability.

As a general rule, the more surface prep you do, the stronger and more durable a bond. Minimal surface prep, such as wiping the area clean, might be fine for simple bonds. For structural strength bonds, more treatment is required.

Here are the types of surface prep you can do, in order of greater effectiveness:

  1. Clean the surface
  2. Degrease
  3. Abrade
  4. Surface Alteration

1. Clean the surface

Prior to bonding all surfaces must be made clean and dry ready to apply your adhesive. Remove as many surface contaminants as possible from the bond area, including dust, dirt, and grease. For delicate surfaces, clean off as much as is practical, especially any loose particles or surface films. If you use detergents or liquids to clean the surface, make sure the surface is dry and void of trace cleaners before applying adhesive. Ideally use CTA IPA

2. Degrease

The next step you can do is to degrease the surface. Degreasing removes all traces of oil and grease (even relatively clean surfaces have oils from fingerprints). If possible, use a solvent such as methyl ethyl ketone (MEK), acetone, or isopropyl alcohol CTA IPA. Wipe the surface clean in one direction. We recommend degreasing whenever possible, because surface oil or grease will get in the way of almost all adhesives and weaken adhesion (with the exception of methacrylates).

How to test if your surface is clean and degreased: For many surfaces, especially metals, a simple test to determine if your surface is clean and degreased is to drip a few drops of water on the cleaned area. If the water spreads to cover the area with a continuous film, the bond area is clean. If the water beads, that means the surface needs to be degreased further. Remember that all surfaces need to be dry before bonding. Also, bond the surfaces as soon as is practical after cleaning and degreasing to avoid having a re-contaminated surface. Also this test will not work well for certain plastics, because the water might bead, even though the surface is not clean enough for bonding.

3. Abrade

For the strongest and most durable bonds possible, we also recommend abrading. Abrading a surface gets rid of surface films, mill scale, paint, and oxides and also gives a much better area for the adhesive to “grip”. We only recommend abrading if practical for the material you are bonding. Use fine grain sand paper (120-200 grit), emery cloth, steel wool, or grit blasting. Abrade enough just to clean and roughen the surface. After an abrasion treatment, remember to remove all loose particles before applying adhesive. Brush the surface or blow with compressed air, and then degrease to clear away all loose particles and residual oils. Abrading and degreasing is enough surface preparation for all but the most demanding industrial applications.

4. Surface Alteration

Finally, some materials are simply difficult to bond. These include EPDM rubber, and “polyolefin” plastics (such as polyethylene, polypropylene, acetal, and hard nylon). Also, some metals such as copper, stainless steel, and aluminum are slightly more challenging to bond than other metals. If you are bonding these materials, you might need to change the surface properties or tension to get good adhesion. Specifically, these are considered low surface energy surfaces, and you need to alter the surface to increase the surface energy. This involves using chemical primers, scorching the surface, grit blasting, or acid etching the surface. Because all materials are slightly different, please call for advice or use our chat box to speak to an advisor. Always first determine if a solvent can be used without harming your material, especially in the case of plastics. Also, note that organic solvents are highly flammable. Follow all safety instructions and local regulations when using such solvents.

Surface preparation can be critical to achieving a satisfactory bond. Feel free to call our technical team to discuss any questions you may have.


Metal bonding adhesives

Two part structural adhesive 2105..With a wide variety of metal bonding adhesives available, CTA can offer great solutions for your project. We can supply in small amounts or offer bulk purchase solutions for larger businesses. Our experience in the industry is huge and our service is unrivalled.

Take a look now at our popular metal bonding products such as our 2 part structural adhesive which is suitable for bonding most metals and plastics. You can purchase directly from our website in large quantities or even trial kits for smaller projects or to experiment with. If you need more help or friendly advice on adhesives for metal (or any other applications), give our team a call on 0121 378 2909 or drop us an email here


Metal bonding glue

Two part structural adhesive 2105..If you’re looking for a metal bonding glue, then we have lots to choose from. In short, it really depends on the application and what you are trying to bond together. We can bond most materials together though as we have a very wide range of products and many years of experience.

Start by checking out our 2 part structural adhesive which is suitable for a very wide range of metal bonding applications. We even have trial kits for sale so the price is kept very low!

Have a browse through our site to see what you need or call us on the numbers above during office hours. You can also use our contact form here to get in touch with any questions.

 


Which Adhesive do I need?

Which Adhesive do I need?  A common question when determining which product to bond substrates together successfully.  This part of our website including it’s links are an informative guide to assist you in your quest for the right adhesive, giving a basic knowledge and understanding of common terminology used in the industry.

• Types of adhesives and adhesive terminology

Adhesive comparison; Advantages versus limitations

Structural Adhesives

Types of adhesive joints


Fast Exhibition 2014

Fast Exhibition banner

Thank you for supporting us at the Fast Exhibition 2014, we hope you enjoyed your time at the Heritage Motor Centre as much as we did, it was nice to meet new people and say hello to some familiar faces.  We were overwhelmed with questions about our products and it was great to to spend some face to face time with you, providing technical support which is what we at CTA do best, provide innovative solutions to your bonding challenges.

This years exhibition we launched our Pre Powder Coat Seam Sealer which is technologically advanced in it’s making and a great addition to our already comprehensive metal bonding range.

Profile

Central Tapes & Adhesives Ltd are a midland based company, supplying specialist adhesive and tape solutions to numerous industries and niche market sectors.  The majority of our products are UK manufactured and supplied throughout the UK, Europe and Worldwide.

A team of people forward thinking, passionate about adhesive with numerous years of knowledge and expertise in the field.  We work hard to retain what is important to our customers;

• Innovative solutions – resolve bonding challenges & provide technical support.

• Improve production processes, eliminate bottle necks and reduce costs.

• Comprehensive range of quality bespoke and made to order products.

• Professional and effective customer service and reliable delivery.

Extensive portfolio of specialist adhesives; two part structural acrylic adhesives, polyurethanes, epoxies, Cyanoacrylate, anaerobic, high bond tapes and much more in our ever expanding product range.  In addition to the CTA brand we are the UK & European distributor for Hernon® Manufacturing, supplying extremely high specification products i.e. MIL specs, offshore etc. which complement our range.

If you are unable to attend the event.  However, wish to discuss any of our bonding range then please contact us, we can visit your premises and perform a demonstration, call our friendly technical team T: 00 44 (0) 121 378 2909 or e-mail us at sales@ctaltd.co.uk or contact us now!


Problem Solving

Problem Solving  this category has been designed to share our knowledge on all aspects of bonding to assist you with your projects and understanding of adhesive selection, Joint design, Loads and stresses on bonded joints.

At Central Tapes & Adhesives Ltd, we are always on hand to discuss your application, visit your premises and provide a demonstration and perform product trials on your behalf. We have the technical knowledge and experience in most industries, we keep up to date with competitor products available in the market place and go above an beyond to remain innovative in providing the best solutions in all your bonding needs.

Please use the following links to help with your adhesive selection:

Types of adhesives and adhesive terminology

Adhesive joint design

Adhesive stress loads

Calculate adhesive quantities

Conversion chart

• Surface preparation for adhesives and best working practice


Stress loads on adhesive joints

Stress loads on adhesive joints can vary from application depending on the substrates being bonded and how pressure/force is loaded upon a joint. It is difficult to determine how differing stress loads on adhesive joints may affect the overall performance and durability of a bonded joint within an application.   Various tests can be performed to ascertain each adhesives optimum performance and also what performance can be achieved when differing stresses are applied to a bonded joint.  Stress is a force applied to a bond, usually expressed in N/mm² (Newton’s per square millimetre) or MPa (Mega Pascals).

Below you will see a variety of diagrams with an explanation about the stresses commonly found in adhesive bonds.  One type of stress is Impact stress which occurs when a sudden force or shock is applied to a joint.  for more information on joints view adhesive joint design. 

Tensile Stress

Tensile stress:   to pull an object apart.  It also tends to elongate an object.

 

 

Compressive stress:  the opposite of tensile stress, compressive stress tends to squeeze an object together.Compressive Stress

 

 

Shear stress:  created by two surfaces sliding over one another.

Shear Stress

 

 

 

Cleavage stress:  occurs when a joint is being opened at one end.Cleavage Stress

 

 

 

 

Peel stress:  occurs when a flexible substrate is being lifted or peeled from the other substrate.

Peel Stress

 

 

 

 

To speak with out technical team on any of the above contact us.

 

 

 

 

 


Adhesive joint design

Adhesive joint design can vary tremendously dependent upon materials, dimensions and various limitations.  This section has been put together to help determine and understand the numerous ways of bonding joints together and how this can benefit in strength and performance or adversely be detrimental to the overall performance and durability of the adhesive joint.

Their are many different attributes that need to be considered when metal bonding, these factors are types of joints, types of stresses and distribution of stress across the joint.

Types of joints

Please view the images on this page to assist in understanding popular joints.  These images are cross sections of joints, grey signifies your chosen metal and blue signifies adhesive.

Double Lap Joint

Double lap joint:   Incorporates two lap shear joints in one.

Butt joint:   Formed by bonding two objects end to end.

Butt Joint

 

Joggle lap joint:   Offset joint very similar to the lap joint.

Joggle Lap Joint

 

Lap/Overlap joint:   Formed by placing one substrate partially over another substrate. Lap Overlap Joint

Scarf joint:   An angular butt joint.  Cutting the joint at an angle increases the surface area.Scarf Joint

Cylindrical joint:   Uses a butt joint, to join two cylindrical objects.Cylindrical Joint

 

Single or Double strap joint:   A combination overlap joint with a butt joint.

Strap Joint

Double Strap Joint

Buiscuit Lid Joint

 

Biscuit Lid Joint:  a variation on a joggle lap joint

 

Flange Joint

 

Flange Joint:  A variation on an overlap joint

 

 

 

Toggle joint:  Formed by fitting the two substrates together in a ‘tongue and groove’ type formation

Toggle Joint

 

 

Stepped lap joint:  a variation of a lap shear jointStepped Lap Joint

 

If you would like to discuss adhesive joint design further, please contact our technical team.

 

 

 

 

 

 

 


How much adhesive do I need?

Bead of adhesive

 

How much glue do I need?    How much adhesive will I get out of a cartridge?

These are the most common questions asked of our technical team here at CTA. Below you will find a quick reference guide to the most popular cartridge and bulk formats used to dispense different adhesives. When dispensing or applying adhesives, you will most likely apply a linear bead. Depending on your application this could be differing greatly in volume and rate of delivery. We have calculated volumes and therefore lengths of the most commonly used beads per tube, cartridge or pail of adhesive. This will help you to answer the question “How much adhesive do I need?”

Bead length chart for CTA Adhesive products

Drag the table left and right to see more.

# 6.35mm : 1/4″ 9.52mm : 3/8″ 12.7mm : 1/2″ 15.8mm : 5/8″
50ml 1:1 3.15m / 124″ 1.4m / 55″ 8m / 31″ 0.5m / 20″
300ml 18.95m / 746″ 8.45m / 332″ 4.75m / 186″ 3m / 120″
380ml 10:1 10.7m / 420″ 1.4m / 55″ 6m / 236″ 3.85m / 151″
400ml 1:1 25.25m / 995″ 11.25m / 442″ 6.3m / 248″ 4.04m/ 159″
Bulk 1:1 / 10:1 240m / 9450″ 106.7m / 4200″ 60m / 2360″ 38.4 / 1510″

Use the above chart to determine the approximate bead length for any CTA cartridge, tube or bulk application in comparison to the bead profile. To calculate the cost of adhesive per part produced, divide the cost per cartridge (or price per gallon for the bulk applications) by the appropriate bead length given above, and then multiply by the length of the bond line on the part.

For any technical help or to talk through your requirements with a member of our team, please call us or use the quick contact form here


MOD and Aerospace adhesive

MOD and Aerospace adhesive and sealants from Central Tapes & Adhesives Ltd have been developed and tested over many years and can be used for a variety of applications such as Bullet sealant, bonding, Thread & Bolt Locking and Bearing Sealants.

We are able to supply military specification products.  We are the UK & European distributors for Hernon® and able to supply extreme high quality and specification products to the MOD & aerospace industry.  Call our technical team to discuss your application.

Trusted Products for MOD Applications

How Hernon can help your MilitaryThe technological world leader for ammunition sealants and application machine technology, Hernon Manufacturing provides trusted, military-grade products for MOD applications.

For more than three decades, Hernon Manufacturing has been a proud supplier to the U.S. GSA and DLA, and our products continue to serve as the preferred adhesive and sealants for modern fighter jets, nuclear submarines, armed vehicles and more.

We make it simple to find the military-grade product you’re searching for. Simply search Hernon product database by NSN number or Mil-Spec. For questions, recommendations or customized formulas for your application, talk with an engineer at CTA.

Ammunition Sealants and Other Solutions for Military Applications

Our dedication to providing solutions for the military continue to this day as our Research and Development team pursue specialty sealants for ammunition, explosives, mines missiles and more to support military applications.

Our military-grade adhesives certify to a military specification and have NSN National Stock Numbers used in military product cataloging. We make it simple to find military-grade ammunition sealants and adhesives for MOD applications on this site.

Please contact us to discuss how we can help cut costs and bring our high quality products to your projects.