Specifications of materials commonly used in Signage Systems.
Material and Process Specifications:
• Acrylic Sheets:
Signage’s need acrylic sheets that are white in colour and translucent so that this could be used for backlighting. It is suggested to use sheets of thickness 2 to 3mm for this purpose. It is essential that these sheets are UV stabilized - especially if they are used outdoors.
The Impact modified acrylic sheets have increased impact strength with no substantial loss of rigidity, and have better light transmission and weathering performance over the acrylic sheets.
Hot Forming:
The sheets can also be Vacuum formed into different forms using a mould.
Specifications:
Tensile strength: 62 MPa
Water absorption: 0.36 %
Light transmission: ca 92%
Suggested manufacturer: ICI Acrylics
• Aluminium Composite Material Sheets:
Aluminum Composite Material has two coil coated aluminum sheets on either side bonded to a thermoplastic inner material. This is available in a wide variety of finishes and colors.
The main advantages of using this material for signage’s is that you can get metallic finishes, its durable and maintenance free and easy to fabricate.
Specifications:
Suggested manufacturers: Di Bond and Aluco Bond
• Aluminium Components:
Fabrication:
- Cleaned and straightened
- Cut to size on shearing m/c
- Bent using guides and fixtures on bending press (only)
- All screw holes drilled
Treatment: Cleaned
Finish:
- Stoving painting withe poxy based paints (baking in oven). or
- Powder coating using epoxy based powders.
• Overall Surface Quality and Finish :
Surface Quality and Finish for all signage’s:
To maintain the quality of the signage the following points may be considered:
- No screws, nuts, bolts, welding marks, cutting marks, edge of the MS sections should be prominently visible from the outside. All details should be worked out from the inside.
- It’s a good option to provide grooves to have the fixing details embedded so that they are not prominently visible from outside. Place visible hinges, screws inside these grooves. If you do not want the grooves to be visible a beading could be fixed to cover it.
- Do not use putting and patching up to cover up misalignments in the panel sizes. Make use of jigs, fixtures and guides while fabricating the parts so that all of them match and align properly.
- Do not use hand painting to finish the surface. The paint should be sprayed in the factory in proper painting booths and not at site. This way you can maintain the required finish (glossy, matt, shiny or dead matt) constantly all over the signage.
- Do not directly paint the MS components - that are prone to rusting. Mild Steel (MS) parts have to be properly treated according to procedure and then only the final coat of finish should be applied.
• Over-laminate Sheets:
Vinyl signage’s can be protected with a transparent and clear, non-reflective, matt UV guard Cast over-laminate film. This will increase the life of the Vinyl stickers as well as offer additional protection from the weather.
Specifications:
- Construction: Polyvinyl Fluoride
- Thickness: 1.9 mil (with adhesive)
- Adhesive thickness: 0.9-1mil
- PVF thickness: 1mil
- Adhesive: PSA acrylic
- Film Cover: Clear
- Adhesive colour: Clear
- Liner: Poly-coated paper
- Dimension Stability: .5%
- Suggested manufacturer:
- Tedlar 7001 manufactured by DuPont,
- Gerber UVGuard by Arrow coated Products,
- 8910 by 3M India,
- DOL 1000 by Avery Dennison.
• Fibreglass Reinforced Polyester:
Glass Reinforced Polyester (GRP) is commonly known as fibreglass. Hand laid process is the simplest form.
In this process chopped glass fibre strand or mat is impregnated with Polyester resin. The application of several layers results in a laminate the thickness of which can be controlled (common thickness between 2mm-3mm). Hand lay process is carried out at room temperature and allows the use of relatively inexpensive mould made out of wood, plaster or GRP. This process is done on the negative mould so that a positive can be taken out.
Process:
- A release agent (wax or polyvinyl alcohol) is applied to the clean mould surface to prevent the laminate from sticking.
- Two coats of UV stabilized gel coat with pigment and along with catalyst and accelerator are applied to give the part its colour and to achieve the desired surface finish. This protective layer thickness should be 0.3mm ± 10% and it is normally given a drying time of between 15 to 30 mins. Depending on the room temperature, humidity and other conditions.
- A coat of UV stabilized Isophthalic Polyester resin along with pigments is applied. One layer of surfacing mat is applied wherever the surface has curves or bends. Once it has gelled to the gel coat another layer of UV stabilized Isophthalic Polyester resin is applied.
- Two layers of fibre glass chopped strand mat in criss cross directions are laid in position. Each mat layer is laid in different directions to maximize strength. A brush or roller is used to remove air bubbles and to make sure the mats are saturated in resin. A drying time of between 4-6 hours is given to this. Use of fillers in fabricating gel coat/laminates is strictly disallowed. Similarly, no additional monomer such as styrene should be added in the resin.
- A coat of UV stabilized Isophthalic Polyester resin is applied and it is left for curing and the surplus fibre and resin at the edges are trimmed away. Curing time can be between 8 to 20 hours.
- After release from the mould, there should not be any blistering or cracking on the surface.
- The finished FRP laminate should have 27%-30% glass loading by weight. This will usually correspond to 1 Kg fibre glass mat: 2Kg resin. Approved Polyurethene painting system on the final surface is also to be applied.
Materials and quantities:
- Fibreglass chopped strand mat (min. density 450gm per sq m) and surfacing mat (30 gsm) are to be used.
- Only UV stabilized Isophthalic polyester resin (UV stabilizer content 0.6%by weight) should be used.
- Gel coat is UV stabilized Isophthalic resin with catalyst methyl Ethyl ketone Peroxide (min 3% sol mixed in the ratio of 2% by weight) with accelerator Cobalt octate(min 3% sol mixed in the ratio of 2% by weight). Pigment (mixing ratio 20% by weight) also needs to be added.
- Manufacturers UV Stabilized Isophthalic Polyester Resin, catalyst Methyl Ethyl Ketone Peroxide, accelerator Cobalt Octoate:
. M/s Bakelite Hylam Pvt. Ltd.,
. M/s Network Polymers Pvt. Ltd.,
. M/s Sunteck Fibre Pvt. Ltd.
- Surfacing mat is in nominal thickness of 0.05cm supplied usually in 1m width rolls of 250m.
Manufacturers:
. M/s FGP Ltd.,
. M/s Owens Corning
. M/s UP Twiga
- Fibreglass chopped strand mat of density 450 gsm. Emulsion bonded:
. M/s FGP(450E), M/s Owens Corning(M705), M/s UP Twiga
. Powder bonded: M/s FGP(450P), M/s Owens Corning(M723), M/s UP Twiga.
- Pigments for FRP: M/s Kerox Ltd., Bangalore.
Warning:
If FRP is not properly UV stabilized, then it will develop cracks after a period of 2-3 years.
• Nuts and Bolts:
All Screws, nuts and bolts that are exposed to outside preferably should be Stainless Steel Fasteners that are Cold Forged. Hexagonal Bolts and Nuts (IS 1364-1983) can be used.
Process:
The nut should be welded to the structure and the bolt inserted from outside.
Suggested Party: M/s Kundan Industries Ltd
Note:
Use of hot dip zinc galvanized MS nuts and bolts are recommended for fixing the structure on to the concrete.
• MS used for Structure:
Fabrication:
- Cleaned and Straightened
- Welded and or bolted together as per relevant drawing and specification
- All screw holes tapped
Treatment:
- Sand Blasting or wire brushing
- Either cold dip phosphating or should be Zinc Galvanized as per IS: 2629-1985 or clean with Metal-prep -25
- Primer Coating (first coat)
Final Finish:
Primer Coated. (Second Coat)
• Mild Steel Components:
MS if used on the outside surface:
Fabrication:
- Cleaned and Straightened
- Cut to size on shearing m/c
- Bent using guides and fixtures on bending press (only)
- All screw holes drilled
Treatment:
- Alkaline degreasing
- Water bath
- HCL acid rerusting
- Water bath
- Water bath
- Phosphating
- Water bath
- Ceiling for crystallization
Finish:
IOC beige colour
- Stoving painting with epoxy based paints (baking in oven) or
- Powder coating using epoxy based powders
Warning:
If the above treatment is not done properly then the MS components will start rusting in humid climates after a period of one year.
• Polycarbonate Sheets:
Polycarbonate is a polymer that is produced as a resin and marketed by GE Plastics under the trade name 'Lexan'. Lexon polycarbonate is available in sheet form. The material is very strong and has tremendous impact resistance and also acts as fire retardant.
Signage’s need polycarbonate sheets, which are white in colour and translucent so that this could be used for backlighting. It is suggested to use sheets of thickness 3mm for this purpose. It is essential that these sheets are UV stabilized - especially if they are used outdoors.
Cold Forming:
The sheets can be cold formed and bent using the normal sheet bending equipment. Experience in this is essential; otherwise the sheets will get bent in odd directions.
Hot Forming:
The sheets can also be Vacuum formed into different forms using a mould. Experience in this is essential, and it is not as easy as vacuum forming acrylic sheets.
Specifications:
- Lexan S - 305 sheets,
- suggested manufacturer: GE Plastics
- Thickness: 2mm, 3mm, 5mm
- UV Stabilized
- Transparency: 32-35%
• Rubber Beading:
Rubber Beading is essential for fixing the polycarbonate sheet to the FRP cladding, to prevent water leakages, etc. made of UV stabilized EPDM rubber with min. 3 years outdoors life should have only carbon constituents with no mineral filling.
Specifications:
- Hardness (shore A): 70 + or - 5
- Specific Gravity: 1.2
- Tensile strength: 90-100 kg per sq cm
- Elongation min: 300%
- Ash content: 10% max
- Suggested Party: M/s Lion Rubber Industries
• Vinyl Sheets:
Self adhesive vinyls are sheets of pre-coloured adhesive vinyl’s for pasting on top of other materials like FRP, Polycarbonate etc. The pre-coloured sheets come in many of the pantone colour ranges.
Text and graphics on pre coloured vinyl sheets can be cut using a drafting cutter connected to a computer that can generate these fonts. The text and graphics can also be screen printed using UV stabilized inks on a clear transparent vinyl.
Vinyl’s and printing inks are made by many suppliers and the prices can vary drastically depending on their quality. It is essential to have the following specifications so that quality can be maintained.
Specifications for Vinyl:
- Film: Premium quality Cast Vinyl film
- Film thickness: 65 - 70 microns without adhesive and 100 microns with adhesive
- Life: make sure it comes with a guarantee of colour stability outdoors for atleast 4 years
Suggested manufacturers:
Avery Dennison or 3M-India
Specifications for the printing inks:
UV stabilized printing inks with an outdoor life of atleast 4 years
suggested manufacturer:
3M-India
Sericol India Pvt. Ltd.
