Special printing technique?
The Argentine postal service issued a series of four stamps on the occasion of the 15th Men's Volleyball World Championship in Buenos Aires, to be held from September 28 to October 12, 2002. So far, nothing unusual, as it is very common for stamps to be issued on the occasion of world championships.
The Argentine team finished third in 1982 with a bronze medal, also in Buenos Aires. In 2002, Brazil won gold, Poland silver, and France bronze. Volleyball players for Argentina include Mariano Baracetti, Martin Alejo Conde, Marcos Milinković, and Alejandro Spajić.
But what is so special about the four stamps? The net! Thanks to a special printing technique, the black net is clearly palpable on the stamps. It lies on top like shimmering threads.
And under strong magnification, it is clearly visible that there are tiny droplets of glue lying beneath the threads. On the first stamp, the threads are so close together that it looks as if an entire tube of glue has been squeezed empty onto them.
Which printing technique was used here? Since I only have one series, it is not possible for me to compare the same stamps. But are all the glue droplets (or whatever they may be) in the same place on the stamps? Or are there any deviations to be observed here as well? Stamps, they never cease to surprise!
The Argentine team finished third in 1982 with a bronze medal, also in Buenos Aires. In 2002, Brazil won gold, Poland silver, and France bronze. Volleyball players for Argentina include Mariano Baracetti, Martin Alejo Conde, Marcos Milinković, and Alejandro Spajić.
But what is so special about the four stamps? The net! Thanks to a special printing technique, the black net is clearly palpable on the stamps. It lies on top like shimmering threads.
And under strong magnification, it is clearly visible that there are tiny droplets of glue lying beneath the threads. On the first stamp, the threads are so close together that it looks as if an entire tube of glue has been squeezed empty onto them.
Which printing technique was used here? Since I only have one series, it is not possible for me to compare the same stamps. But are all the glue droplets (or whatever they may be) in the same place on the stamps? Or are there any deviations to be observed here as well? Stamps, they never cease to surprise! 
It has remained deafeningly silent regarding the question: how were these stamps printed? I had hoped that Rein, who knows EVERYTHING about printing techniques, would have answered this. But perhaps that will still happen?
'@Cees
I would have to see the stamps myself, but they remind me of Turkish stamps from 1963 [?] in offset, where a special effect was achieved using heated resin powder. I think the term “heatset” was used back then, but nowadays that term is used for many more things….