Customers regularly ask us for “double sided flags” sometimes not really knowing or understanding how they are made, leading to misunderstandings, especially when trying to reply to e-mails. Our question is always – ” Does this customer really know how they are made, and do we need to explain”
We understand the confusion; the flags which most people see when walking down the street, or at events and festivals, do appear to be printed on both sides. It is the general assumption that flag fabrics are the same as paper you have to print on both sides, to produce an image both sides.
Since the colour density is full and rich, to both the front and the back, they must have been printed on both sides ?
This however is an illusion. While it is possible to print both sides of flag textiles, the technique of doing so requires a much heavier weight fabric, and a printing process not usually associated with flag making.
Most feather flags are digitally printed using one of two techniques
Understanding how double sided feather flags are constructed, therefore requires some explanation of both the fabrics used and the printing processes.
Feather flags are normally printed on lightweight polyester fabrics, normally 110 gm – 160 gm per square metre. Their key feature is that the yarns are knitted, not woven. As a consequence they are not only porous to the wind, but also porous to printing ink. Printing inks are applied to one side only, and depending on the process used, they will permeate to some degree to the rear. The colours to front and back are almost the same density, hence the illusion of being printed – both sides : The rear image is however always is mirror of the front.
Dye sublimation is the most popular method of digital printing. With this method, the ink is sprayed onto the flag fabric, and as a liquid it permeates from the surface though to the rear. The inks are “fixed” by heating to 200+ degrees. The ink however only colours the surface of the yarns.
Disperal printing, is similar but in this process the inks are vaporised, and as pressurised gas are blown into the fabric. Since the ink molecules are smaller, they penetrate more into the polyester yarns, rather that just staying on the surface, giving a more durable and colourfast print. Again the ink is fixed using a high temperature fan. The dispersal process also demands both washing and ironing post printing.
In both cases visual impression is a flag which has been printed on both sides. The graphic, text and images, will be visible from both sides, but obviously the rear will be a mirror image of the front. In most situations this may not matter too much, since the brain is perfectly capable of interpreting images, text and logos, the wrong way round, as it does faces. And for branding and visibility, this construction should satisfy almost all situations. However they are not truly “Double Sided”
Double Sided Printing
For the design, texts and logos to be right reading both sides, there has to be two printed layers. If you print an image on the two pieces of paper, place them back to back and hold them up to the light, the outline shapes will not coincide. The same true with flags. And since both prints are porous, the amount of show through will be significant.
Manufacturers will try to limit this show through by adding a third, interlayer. This may be the same fabric as use for the outer layers, it may be a heavier more opaque material, or it may be a lighter fabric in a dark colour for example – black. The result however, will be a flag at least three times as heavy as the single layer. And this has important consequences how it performs, and for safety.
Show though is going to be a a major problem, and whatever style of interliner the manufacturer may use, it cannot be totally eliminated. To overcome many of the issues regarding show through, the design has to be symmetrical ; images and text should be centrally placed. The final positions of each element of the design, should be in the same position on each panel – and be so to mm accuracy. Design costs are usually more than twice that for the single layer.
Double sided flags, because of their increased weight will have greater inertia : they do not flow or flutter in the wind as actively as would single sided. Colleagues have described the performance as “fly like bricks” or “limp” which are the best descriptions I have some across.
Safety will be the most crucial consideration when and when not to use double sided flags. The two extra layers, have already increased to weight of the flag, and the lack of inertia, and its ability to flutter, will increase the amount of water that will absorb during periods of rain. If a single side flag is recommend for use at wind speeds below 20 mph Force 4: then the recommendation for the same size double sided version would be 14 mph.