Questions from Sign Makers

2.1. BSGA Membership and Commercial

Q: Why should my company become a member of the BSGA?
A: The BSGA is a pro-active organisation working on a continual basis across a number of key initiatives and member services. In addition to the marketing advantages membership provides, members have access to, and a voice in the services provided by the Association. These include: Technical Guidelines, Education, Representation and Planning. For more information on the Association and how to become a member, follow the links from the home page of the BSGA web site.

Q: What are the benefits to my company of BSGA membership
A: As a member of the BSGA you will have access to a wide range of services and benefits. You will also have the opportunity to promote your company through the BSGA web site, the primary portal for the sign industry in the UK. The unique Sign Search facility gives members have the opportunity to reach sign buyers and specifiers across the country.

Q: What will the BSGA do to market and promote my company?
A: The BSGA have a number of marketing initiatives aimed at promoting its members and their services. The primary one being this website which now features a sponsored link on Google, the world’s most used web search engine. Through our web site sign buyers can find all members of the BSGA and identify those with the specific skills to meet their requirements. The BSGA web site also provides facilities for signmakers to source the materials and equipment they need and, through the SignPost forum, to debate online any subject close to your heart with other signmakers.

Q: Will the BSGA recommend my company to a potential customer?
A: The BSGA is a trade association whose primary aim is to represent the interests of its members and promote the high standard of quality, design, workmanship, health and safety and commercial practice within the sign industry. As such we do not recommend one member over another however; we do provide members with opportunities to promote their companies. The most significant of these is the Sign Search facility of the BSGA web site, the major internet portal for the sign industry in the UK.

2.2. Finding a Supplier

Q: How or where do I find a supplier?
A: The quickest and easiest way to find a supplier for a particular item or material is to use the Supplier Search facility on the BSGA web site. This unique facility, not only allows you to find and select a supplier, it includes company profiles and gallery images which allow you to see their products.

2.3. Materials and Processes

Q: What are the differences between cast and extruded acrylic and how does this influence my selection of the [correct] material?
A: Cast and extruded are the two principles manufacturing methods for acrylic sheet.

Cast acrylic sheet is formed between two sheets of glass and generally has wider thickness tolerances, is available in a greater range of colours and textures, has a better surface spread of flame rating and due to its smaller batch size production method can be obtained sooner and in smaller quantities for special colours etc.

Extruded acrylic sheet is produced on a continuous production line by extruding the acrylic through a die to form the sheet material. This process results in better consistency with good thickness tolerances and typically lower cost. Due to their different molecular structures the two types of acrylic sheet behave slightly differently to one another, extruded sheet is easier to thermoform and well suited to the vacuum forming process whilst cast sheet is more resistant to thermoforming and consequently best suited to pressure forming where definition is not an important factor.

In flat panel applications the higher molecular weight of cast acrylic gives it a better creep resistance and hence, tends, especially for thinner sheets, to resist warpage associated with moisture absorption.

Q: What’s the difference between Cast and Calendered vinyl?
A: Cast and calendared refers to the two different production methods for vinyl films. Cast vinyl film is considered to be the premium material and benefits from better dimensional stability, thinner film thicknesses, and better conformability. Cast vinyl film can also be expected to have a longer service life in outdoor applications with better colour retention and durability. Calendared vinyl films are generally thicker making them easier to handle and due to the high volume nature of their production process a cost effective alternative to premium priced cast films.

Q: Can I laminate two pieces of clear acrylic to one another without the use of adhesive?
A: Techniques do exist to allow the production of clear laminates; however they have not been widely used by the industry as they can be restricted in terms of the area of lamination. Typical techniques for laminating large areas of acrylic are either by the use of adhesives or double-sided tapes.

Q: Are VHB tapes and structural adhesives better than mechanical fixing?
A: The use of very high bond (VHB) tapes and structural adhesives is now commonplace within the sign-manufacturing environment and often driven by the demands of design for concealed joining methods. VHB tapes are relatively quick and easy to apply to prepared surfaces, but are unsuitable where post-painting processes are required as heat and solvents will affect them. Structural adhesives perform well but typically require components to be clamped together during their cure time slowing process times likely to result in higher volumes of ‘Work in Progress (WIP)’. The use of adhesive bonding often results is a stronger, weatherproof join where the load is more evenly distributed.

Although often visible, mechanical fixings benefit by good alignment and faster process times due to the self-jigging capabilities. They are not reliant on clean, dry prepared surfaces, survive post processes such as painting and powder coating better and are the most suitable fixing method for use on site. Typically mechanical fixings are more cost effective.

2.4. Technical

Q: Where can I get advice on…
A: The BSGA publish a number of Technical Guidelines, available exclusively to members, which cover a range of topics including sign design and manufacture, health and safety, and environmental regulations. In addition we provide a telephone helpline service and an ‘ask-an-expert’ facility via our web site.

Q: How do I find out the expansion and contraction rate of substrate(s)?
A: Expansion and contraction of materials is an important design consideration for external signs, particularly long fascia signs to shops, petrol filling stations etc. To determine the thermal expansion of any material it is first necessary to know the ‘Coefficient of Thermal Expansion’ or ‘Thermal Expansivity’ often expressed as 10-6 per ^oC. The coefficient for thermal expansion of aluminum is 24x10-6 per ^oC or 0.24mm per 10^oC per M. For a south facing aluminum skinned sign within the UK an expected temperature range of 50^oC is considered reasonable. Therefore given a 2.4m sign panel the expected expansion/contraction is (0.24x5)x2.4 = 2.88mm. For further information refer to BSGA Technical Guideline C2.5(c).

Q: What method do I use to compare the different thermal expansion of plastic substrates?
A: Similar methods are used to those outlined above for metal substrates. However, for plastic materials the expansion is typically greater than for metal products. Taking acrylic as an example, a typical expansion allowance is of the order of three times the vale for aluminium e.g. 0.7 mm per metre per 10^o C. It is therefore more important on large panels to expansion allowances exist for acrylic and other plastic substrates.

Q: What is the difference between low and high voltage signage and what are the consequences?
A: In the sign industry low voltage refers to a sign using mains voltage and often fluorescent lamps (hot cathode) for illumination (230V) and high voltage refers to the use of neon (cold cathode) for illumination (5000v). National and International standards govern both low and high voltage means of illumination and it is essential that the designer/manufacturer complies with and is trained in the use of these standards if a serviceable and safe product and installation is to be ensured. BSGA members can find specific details of the standards in the relevant Technical Guidelines, which are available in the Members area of the web site.

Q: How do I measure gloss levels for paint finish?
A: Gloss is measured by shining a known amount of light at a surface and quantifying the reflectance. The angle of the light and the method by which the reflectance is measured are determined by the aspect of the surface appearance to be measured. A universal gloss meter or reflectometer having a reflectance angle of 60^o is used for measuring flat surface of paints, metal, anodised aluminium and varnish.

Q: What are the permissible levels of illumination for an external sign?
A: Guidelines for the ‘Upper limits of Luminance (cd/m2) For a Given Location’ are published by the Institute of Lighting Engineers (ILE). BSGA members can also find the information in Technical Guideline C2.2(a), which is available in the Members area of the web site.

Q: What formula do I use to compare the power consumption between different forms of illumination?
A: Different types of illumination may be considered for a sign, fluorescent (hot cathode), neon (cold Cathode), light emitting diodes (LEDs) etc. and its first necessary to determine the number and positioning of the light source as well as the required level of luminance to give an even and uniform illumination. Once this has been done the power consumption and capital cost (and its recovery) can be calculated for each type of illumination being considered. For calculating the power consumption:

• System watts - w
• Number of operation hours per annum - h
• Kilowatt per annum rate - kA
• Kilowatt hour rate - Kh

Total power consumption per annum - (wxh)/1000 = kW
Total running cost per annum - (kWxkH)+(kAxkW)/1000

Q: What typical value can I use for the minimum ground bearing pressure for an external sign within the UK?
A: In general for a UK application a minimum ground bearing pressure is 50kN/m2 can be assumed; however if a specific figure for the site location should be obtained. Foundations are normally calculated using a concrete mix is in accordance with BS CP110 (Structural use of concrete) Grade 20/20. 20 refers to strength @ 20kN/m2, 20 refers to aggregate size in mm. Recommended curing time 7 days minimum.

Q: What basic wind speed/pressure should I apply for design of externally signs within the UK?
A: Wind codes for the UK are published in BS6399-2:1997 ‘Loadings for Buildings – Part 2: Code of practice for wind loads’. Figure 6 ‘Basic wind speed Vb (in m/s) shows the wind contours for the UK. For generic application throughout the UK a basic wind speed of 25m/s it reasonable but it should be noted that locations in the extreme north and far west of the UK exceed this basic wind speed.

Q: Why should I use more expensive tri-phosphor coated tubing for neon or cold cathode lighting?
A: The phosphor coating to the inside of a lamp enables a wide range of different colours and quantity of light to be emitted.

Tri-phosphor coatings combine the 3 colours of blue, red and green, and by adjusting the proportions of these colours in the phosphor mix colour temperatures of ‘White’ between 2700 and 6000 K can be achieved. Tri-phosphor lamps give high efficacy with good colour rendering, in normal lighting applications the extra cost of tri-phosphor lamps is often offset by the reduce number of lamps required, however for signs the primary requirement for an even and uniform appearance can conflict with this benefit.

In summary, tri-phosphor lamps offer a higher lumen output, improved colour rendering, greater range of colours, improved efficacy and longer maintenance life but at an extra cost and there is a need for greater care in design to achieve an even and uniform appearance for an illuminated sign face. Some of the benefits of tri-phosphor lamps are not advantageous to the sign designer and maintenance life aside single phosphor lamps are often the preferred choice.

2.5. Education and Training

Q: How do I become a Signmaker?
A: There are a number of routes to becoming a signmaker including Foundation and Advanced Apprenticeships, which are designed to bring suitable young people into the sign industry. These apprenticeship schemes are complimented by the S/NVQ qualifications in Signmaking. Details of these and other courses are available in the Education section of our web site.

Q: What training courses are available for Signmakers?
A: There are a number of training courses available for signmakers; these include the S/NVQ at Level 2 and Level 3 which are supported by the BSGA. For more details of these and other courses or to download a BSGA information leaflet ‘A Structured Approach to Developing a Better Workforce’ please go to the education section of our web site.

Q: Where is my nearest college offering NVQ in Signmaking?
A: Contact details for all the colleges and accredited centres offering the S/NVQ qualifications in Signmaking can be found in the BSGA Members Directory, which can be accessed from the home page of this site.

Q: What is a CSCS Card?
A: The Construction Skills Certification Scheme (CSCS) card is the easy way to prove that you are competent in your occupation and have health and safety awareness. It is the size of a credit card, has your photo and unique reference number on it and is easy to slip into your wallet to use as instant identification when you arrive on site.

You can get more information on the CSCS scheme, which has been in existence for over 10, by going to the CSCS web site at www.cscs.uk.com

Q: What do I need to do to get a CSCS Card?
A: After negotiations with CSCS the BSGA have agreed a route by which sign installers may obtain a CSCS card. A short leaflet prepared by the BSGA, which details of the requirements and the application process, can be downloaded from the Legislation section of our web site.


> top of page