Vacuum Formed Pan and/or Embossed Plastic Sign Faces

 THERMOFORMING DEFINITION  If your plastic sign face is to be unusually shaped, three-dimensional, or two-dimensional with a lot of surface detail, it is essential to choose a sign plastic with excellent thermoforming characteristics. Definition is such a characteristic. Good definition means that the plastics material under consideration is capable of forming to very sharp profile contours. Here at Magic Signs we pull at a high vacuum close to sea level and that gives a lot of force to the product, Good tight edges and detail in all products just not plastic sign faces.

 FLEXURAL STRENGTH  This is another way of saying ‘stiffness," and it is measured in terms of "flexural modulus?’ The higher the modulus, the greater the stiffness. The greater the stiffness, the less likely it is that the sign-face material will bow in or out, thus distorting the appearance. (This is a particularly important consideration with flat sign faces.) Obviously, in virtually every situation, good flexural strength (high flexural modulus) is what you want. Modified acrylics, polycarbonates and UV resistant PETG have lower flexural modulus. They will flex and bend more than standard acrylics, which in general have the greatest flexural strength. UV-modification of polycarbonates reduces flexural modulus only slightly. Low modulus can be modified by increasing sheet thickness, or by bracing the sheet to compensate for high wind loads. Sign faces with low modulus should be top hung, not merely fitted into their retainer system.

We take flat plastic and put it into a special designed oven, heat up the plastic and the vacuum pulls down the plastic over a mold to form a plastic pan face. Pan  embossed forming adds to the rigidity of the plastic sign  face.  Text or graphics can either be sprayed to the second surface (back of pan) or vinyl can be applied to the first surface (front) of the pan face. Pan faces can also be used as reader boards or changeable letter signs by adding tracks.

SIZE Is the sign you need too large to be formed of a single sheet of plastic? If so -- and it has to be fabricated in sections  the seams between sections could spoil the look.

 CLARITY The "second surface"— that is, the inside surface of the plastic sign face, unexposed to the elements -. is where most sign decoration is applied. That means there’s a sheet of plastic between your message and the customer. Clarity (light transmission) of the plastic therefore becomes of the first importance, because you want your logo and message to appear in their true colors.

 SURFACE TEXTURE The surface appearance of your sign should be a specific decision. Would a glossy or matte (dull) finish provide better readability? Most standard sign-face plastics are available in both matte and smooth textures. Custom textures for formed plastic sign faces can be achieved by lining the  sign face mold with different materials. Formica, brushed metal, pool table felt and other materials are used by thermo formers to achieve specific surface appearance.

 FLAT OR EMBOSSED PLASTIC SIGN FACE The two primary options are flat plastic face or formed (embossed) plastic face. In the case of an embossed sign face, especially one with variations in surface detail, the plastics material you need is one that will deliver maximum crispness of detail after the thermoforming process. Flat plastic sign faces need to be a stiff material, because they do not get the increase in rigidity that embossing adds to sign faces.

 YELLOWING The most evident effect of the elements on a rigid  plastic sign face is yellowing. This is particularly true of plastic sign faces with white backgrounds. For long-term clarity (8-10 years), the acrylics are often recommended because they will not significantly alter the color of the underlying sign graphics during that time period. But today’s UV resistant plastic sign-face materials are also excellent for long-term color retention, and can be used very successfully with white backgrounds.

 UV-DAMAGE A UV problem related to the yellowing of the plastic sign face itself is the fading of the design painted on the second surface, that is, on the inside surface of the sign. In this connection, UV resistant PETG and polycarbonate can actually out-perform the acrylics in laboratory testing, and as SIGNS OF THE TIMES magazine stated in its February 1992 issue, sign-users have often failed to recognize the long-term value of using UV-treated sign plastics.

 WATER HAZING This is an additional weather-related problem, especially in climates where high moisture levels combine with high temperatures. Standard acrylics score highest on tests for this kind of haze-resistance, while "ultra-weather able" polycarbonates run them a very close second.

 HEAT DISTORTION Heat distortion is especially important to the retaining system of a sign. In construction, allowance must be made for heat expansion which might bow or buckle the plastic sign face. The most desirable characteristic, obviously, is minimum thermal movement (an important cost factor) because a plastic sign face with minimum thermal movement enables the fabricator to use the smallest possible and therefore the least expensive retainer. Remember, the heat generated by the sign itself must be considered. For signs with high-temperature lighting -- such as with mercury vapor or incandescent lamps -- additional ventilation may be required when utilizing materials with lower HDT (Heat Deflection Temperature) ratings. (For signs used in extremely cold climates, of course, low temperature contraction must be considered. Such contraction can result in the plastic sign face surface pulling out of the retainer.)

 IMPACT STRENGTH Impact Strength means the ability of a material to withstand being struck by projectiles, and the standard testing procedure is the ‘falling dart test," using a free-falling steel weight. Polycarbonates and PETG offer the best high-impact resistance, and their impact strength improves with higher temperatures. In general, extruded plastics have a higher impact-resistance than the cast plastics. Although the acrylics have the least impact resistance, they generally have greater tensile and flexural strength. Something to look out for: because polycarbonates have such high impact strength, thinner sheets can be and are used, and therefore the amount of wind-deflection and the resulting tendency to pull out of the sign box retainer are increased.

 TENSILE STRENGTH Tensile strength simply means the strength of a material when under tension. Tensile strength is critical at points where the sign face is being retained, because the weight of the face, plus tension created by wind against the face, increase the pressure on the retainer. Tensile strength is especially important when considering single or double-faced signs to be mounted on a support column, or wall signage to be installed at a height of thirty feet or more.