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Invisible ink, also known as security ink or sympathetic ink, is a substance used for writing, which is invisible either on application or soon thereafter, and can later be made visible by some means, such as heat or ultraviolet light.
Homemade ink. On left, a solution of iron (from nails) and vinegar. On right, oak extraction. The two are mixed immediately prior to use to produce the ink, centre. The ink was traditionally prepared by adding some iron(II) sulfate (Fe SO 4) to a solution of tannic acid, but any iron ion donor can be used.
Messages written by a UV marker can be discovered by unintended viewers when there is a change of reflectivity of the paper, or a pen scratches marks on the paper. The smell of the ink also reduces the security of secret messages as the hidden messages can be easily found with the help of trained animals.
Fill it to the MAX line with fresh water and perform 12 rinsing brews using the largest cup size to remove any traces of vinegar or descaling solution. Re-insert or replace the water filter. How ...
The different cartridge must be smaller in some dimensions than the original design cartridge, and since smaller cartridges are usually cheaper, the device allows less expensive fire practice. Alternative names sometimes imply the type of dimensional difference. A chamber insert may be used for a shorter cartridge of similar base diameter.
Research to determine whether it is possible to calculate the service life of respirator cartridges (if one know the conditions of their use) have been conducted in developed countries since the 1970s. This allows one to replace cartridges in a timely fashion without the use of sophisticated and expensive equipment. [citation needed]
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The decoder pen, yes-no pen, yes-know pen or magic pen book is a combination of decoder pen or marker specially designed to reveal invisible ink-encoded pictures or writing, [1] in the form of answers to questions or hidden parts of pictures, with specially created children's books with hidden words and pictures. They were most popular in the ...