Cleaning procedures, color reaction

Color Reaction to Historic Cleaning Procedures. Another set of colorfastness tests was adapted primarily to simulate conditions under which the dress may have been cleaned. X-ray analysis indicated the presence of potassium and the higher levels of sulfur on the dress, as compared with the unused remnant. In the earlier X-ray analysis, the Kevex-ray detected some detergent residues on the washed specimen. It is possible that the elements detected on the dress could be residues from cleaning processes used earlier in this century, which might have been used to care for this dress. 

Table IX. Color Reaction to Historic Pretreating and Cleaning Procedures...

Color reactions are carried out either in test tubes of various sizes, volumetric fls sks, and graduated cylinders, or in the form of spot tests on an analytical filter paper, or on white porcelain spot-test plates (provided with small hollows). The procedure depends on the nature of the reaction, on the amount and character of the sample, and on the skill of the analyst. The majority of reactions can be adjusted in various ways. As regards reagents and auxiliary solvents, etc., the same remark is valid as that on p. 55 for reagents and derivatives. The scrupulous cleanness of the vessels and of all auxiliary substances and solvents (which can be checked in control experiments), as well as very accurate and neat work should be a matter of course for every analyst. 

After completing the cleaning trials, the test substrates were visually examined under a microscope (40x) for residues. An ionic contamination test was performed on each substrate. To reveal activator residues from flux not shown by the ionic contamination test, the flux test, a qualitative color-reaction test, was applied on each individual substrate. This testing procedure detects the carboxylic acid-based activators from the flux, and provides exact information regarding the location and distribution of the acidic impurities (Figure 3). 

Highiy dried toiuene is the most usefui reaction medium.lt is obtained according to the foiiowing procedure. Pre-dried toiuene (over moiecuiar sieve) is refluxed over a iiquid sodium/potassium aiioy (5-10 mi for 2 i of toluene) for 4-5 days. An alternative method is the addition of n-butyllithium in small portions (ca.10 ml for 21 toluene) which can be visualized with benzophenone as indicator. When the toluene is sufficiently dried (change of color) it is distilled off and stored under argon (The used syringes or pipettes have to be flushed prior to use with argon after use they have to be cleaned immediately with toluene). 

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