Acid wash to the 30c plate NGR
This 30cNGR specimen (a PERFIN) shows evidence of acid washing to the plate.
[Blockierte Grafik: http://www.somestamps.com/images-arg3551/reference-collection/foro/200906/PERFINs/CQ/arg3551-PERFINs-CQ-06.jpg]
[Blockierte Grafik: http://www.somestamps.com/images-arg3551/reference-collection/foro/200906/PERFINs/CQ/arg3551-PERFINs-CQ-06-b.jpg]