UK weather poses unique challenges for outdoor signage. With everything from damp rain and gusty winds to intense sunlight and coastal salt exposure, it’s crucial to choose materials, print methods, and assembly techniques that stand up to the elements. This article explores the best practices in sign blank materials, printing/vinyl application, and assembly techniques to help you create signage that endures.
1. Sign Blank Materials
Selecting the right base material is the foundation for a weather-resistant sign. Here’s a look at common options:
PVC Foam Board (Foamex, Foamalux)
- Pros: Lightweight, easy to work with, and cost-effective for short-term projects.
- Cons: Best suited for temporary outdoor use. Over time, PVC foam board can shatter and become brittle, especially when exposed to prolonged heat. Black foam, for instance, tends to absorb heat, causing warping and expansion.
Aluminium Composite Panel (ACM)
- Pros: Offers an excellent weight-to-strength ratio and a rigid structure. ACM is versatile—ideal for post and panel signs, wall-mounted signage, tray signs, and shop fascia's. It also comes in different grades, with thicker aluminium skins (around 0.3mm) recommended for long-term exterior use.
- Cons: Thinner skins (around 0.12mm) can bend easily and are prone to delamination, particularly in coastal areas where weather conditions are harsher. Manufacturers typically guarantee the sheet before it’s cut into shape, so flat cut letters might risk panel delamination.
Cast Acrylic
- Pros: A high-quality material often used for entrance plaques, shop fascias, and lightbox panels. Its clarity and finish are ideal for premium applications.
- Cons: Acrylic expands and contracts with temperature fluctuations. When using wall mounts or standoffs, oversize the holes to accommodate expansion. Also, if the sign is in a high-traffic or vandal-prone area, consider alternatives such as polycarbonate due to acrylic’s tendency to shatter on impact.
Solid Aluminium Sheeting
- Pros: The traditional choice for durable road signs, tray signs, and shop fascias. Solid aluminium offers excellent durability, can be powder coated to custom RAL colours, and is available in popular thicknesses (typically 2mm or 2.5mm).
- Cons: Fabrication requires more skill—welding may be needed before powder coating. In rural areas, its high scrap value can make it a target for theft, and it is generally more expensive than ACM.
2. Printing and Vinyl Application
Decorating exterior signage typically involves printed or self-coloured self-adhesive vinyl, or direct-to-substrate (UV) printing. Each method has its own set of considerations:
Vinyl Application
Types of Vinyl
- Monomeric Vinyl: The most basic type with the shortest lifespan (2–5 years). It tends to shrink and fade, making it suitable only for short-term or promotional signage.
- Polymeric Vinyl: Offers improved dimensional stability and longevity. Modern polymeric vinyl can now achieve lifespans of up to 8 years.
- Cast Vinyl: Manufactured to provide excellent stability and the ability to conform to 3D surfaces (ideal for vehicle graphics or curved fascias). This option can last 12 years or more.
Additional Vinyl Options
- Self-Coloured Vinyl Face Films: Best for simple signage with limited colour use. While monomeric versions are acceptable for short-term use, polymeric films are preferred for longer-term installations.
- Printed and Laminated Films: With advancements in print technology, sign shops can produce high-quality prints in-house. Matching the print and laminate from the same product line is critical—mismatched shrinkage rates can lead to tunnelling or cracking.
Direct to Substrate (UV Print Application)
- Advantages: UV printers apply ink directly onto the board and cure it with UV light, significantly speeding up production.
- Considerations: Despite being advertised as not requiring lamination, UV prints can be vulnerable to scratching, fading, and failure. If lamination is applied, ensure the laminate has an extra thick adhesive coat to overcome the slight raised profile of the UV ink and avoid “silvering” around the graphic edges.
3. Assembly Techniques
Even with the best materials and print applications, the final assembly plays a vital role in ensuring longevity and weather resistance.
Adhesives and Double-Sided Tapes
- Double-Sided Tapes: Commonly used for post-mounted signage, structural bonding tapes like Stykra 700 EXT require a strict cleaning, priming, and application process. This is particularly important when bonding low surface energy (LSE) materials like plastics and powder-coated surfaces—always choose an LSE-compatible tape.
- Adhesives: MMA or PMMA glues (e.g. Stykra 1000 or 4000) are widely used for bonding components such as locators to flat cut lettering or aluminium angles for reinforcing sign trays. Caution is advised with fast-curing adhesives; the exothermic reaction during curing can cause “read through” issues, where the heat deforms the sign material.
Traditional Assembly Methods
- Mechanical Fixings: Techniques such as using rivets or welding are still popular, especially for larger scale projects and architectural signage. Flush riveted panels, for instance, are favoured for highways signage, though they require specialised machinery.
- Welding and Fabrication: For bespoke or larger projects, welding remains a robust option. This method is typically reserved for manufacturers with full workshop facilities and is ideal for high-quality, custom production.
Conclusion
For UK signmakers, designing weather-resistant signage is all about matching the right materials with the appropriate print and assembly techniques. Whether opting for the economical ACM or the high-quality solid aluminium, understanding each material’s strengths and weaknesses is key. Similarly, choosing the correct vinyl or print application, along with meticulous assembly methods, ensures that your signs can withstand the unpredictable UK weather—providing reliable, long-lasting performance.
Adopting these best practices will help you deliver products that not only look great but also stand the test of time, regardless of the elements.