is possible to print flags with the screenprinting? If yes how?
Which fabric should be used as substrate?
Good flags are usually sewn together by color. Crappy flags can be easily printed. You can buy Nylon, polyester or similar synthetic banner material in any color. Just choose an ink based on what the banner material is made out of.
Most flags are printed using a dye sublimation process, wherein a chemical reaction bonds pigments to the actual fabric (Dacron and Poplin are two popular fabrics these days). Double-sided flags are often printed as two separate one-sided panels, and an opaque center piece is sandwiched between the two and the whole thing gets sewn up to prevent shine-through.
I would not recommend screenprinting flags, as the weight of the ink will have a substantial effect on the natural wind flow and hanging of the material, and likely the ink will crack over time due to the stress of the wind.
Your best bet is to sub something like this to a company that specializes in custom-printed flags. The equipment is too expensive to try and acquire on your own...
I did a consulting report for a company called the flag shop in vancouver, they print flags and street banners.
the flag material is stretched out and pinned to a table that has a thin cushion of foam, covered by a thicker fabric. this gives the printing base some flex.
Screens are prepared normally. the ink is actually a dye they mix up for each job - pigments and base, the same type of dye they use for textile bolt printing.
Screen is laid on the fabric - the tables are 100 feet long, and they have a guide rail along the side. Fabric is stretched over the whole table.
two people, one on each side, put the screen in place, they pull the squeegee one way, then the other. they don't flood.
they pick the screen up and move to the next stop on the guide rail and repeat.
for the second or next colors, they look through the screen to align the color then print and work their way down the line.
After all printing (the ink dries quixk) the fabric gets rolled with paper into metal sleeves. the sleeves go into a steamer. the steamer cooks the dye, producing the color and locking it in the fabric.
It;s then washed in setting solutions, then dried.
flag is then cut off the bolt and hemmed.
that's how it's done. the dye ink has no body after it is processed, it's just part of the fabric.
Yes this place also sews flags together too.
they also have a couple of digital printers
Fabio, Italy is one of the centres for fabric printing, they have automated roll to roll printers like this they make there. this method with the tables is old school, but still very common in third world countries where they make textiles. it used to be more common in North america, but people lost the technology when the manufacturing moved offshore. There are 3 places in Canada still do this, and probably a bunch more in the USA, but they are hidden. It's still the most economical way to do bold color graphics on fabric. Subdye is good for full color, but way more expensive when you get into quantity and not as durable.
thanks for the clarification. I imagined the old school method was the one with the long table and the rails. I've discovered it when looking how to print "furoshiki", the traditional Japanese foulard. the dyes imho are really fascinating.
A day i'd like to create a (little) table for small runs of 50-100 pieces.
Have you got Andy experience with the dyes, like Procion MX on fabric?
A customer asked to me 10 (ten) flags, so i believe i must go and find somebody who prints digitally on fabric with a (damned) plotter.
i worked for a flag shop that did custom flags for a few months. we cut the colors out of nylon on a huge plotter and then sewed them up. it was tedious and expensive but everyone always told us it was a lot better than getting them printed.