Logwood

Silk (qv) suture is made from the threads spun by the silkworm Bombjx mori. The fiber is composed principally of the protein fibroin and has a natural coating composed of sericin gum. The gum is usually removed before braiding the silk yams to make sutures in a range of sizes. Fine silk sutures may be made by simply twisting the gum-coated silk yams to produce the desired diameter. White silk is undyed. Silk is either dyed black with logwood extract or blue with D C Blue No. 9. The suture may be uncoated or coated either with high molecular weight polydimethylsiloxane or with wax. 

Nylon-6 [25038-54-4] (9) is made by the bulk addition polymerization of caprolactam. Monofilament Nylon-6 sutures are avadable undyed (clear), or in post-dyed black (with logwood extract), blue (ED C Blue No. 2), or green (D C Green No. 5). Monofilament nylon-6 sutures are sold under the trade names Ethilon and Monosof monofilament nylon-6,6 sutures, under the trade names Dermalon and Ophthalon and monofilament polyethylene terephthalate sutures, under the trade name Surgidac. 

Logwood extract—A reddish brown-to-black soHd material extracted from the heartwood of the leguminous tree Haemato>y/on campechianum. The active colorant substance is principally hematein. The latent coloring material is the unoxidized or leuco form of hematein called hematoxylin. The leuco form is oxidized by air. 

Logwood [8005-32-2] (Cl Natural Black 1 Cl 75290) is a modified ben2opyrone, and was the last of the natural dyes to survive after the appearance of synthetic dyes because of the desirable bluish-black hue it produced on chromemordanted fibers. However, for economic reasons and because it requires a mordant, it too is no longer used commercially. 

Although logwood had been known for several hundred years, it did not achieve technical importance until it was discovered that it combined with metallic salts to give various colored lakes, of which the chrome lake was the most important (81). After an enormous amount of research, the present formulas for the dye components were proposed (82) and later substantiated (83). 

Blank-draht, m. bright wire galvanized wire, -film, m. (Photog.) film base. -fix. blanc fixe, permanent white, -holz, n. logwood, blankkochen, v.t. (Sugar) boil down without gr ning. 

Braun-spkne, m.pl. logwood shavings, -apat, m. dolomite. 

Waid, m. woad. -blau, n. woad blue, woad. -farber, m. woad dyer, -kupe, /. woad vat. -kupenschwarz, n. woaded logwood black. Wal, m. whale. 

The mordants may be applied to the substrate either before, during, or after application of the dye. Premordants, as the mordants applied before the dye are known, seem to have been the most commonly used in antiquity. Some mordants not only are instrumental in attaching the dye to the fibers but also alter the shade and even the hue of some dyes a single dye often provides a range of hues when used with different mordants. The color or hue of textiles dyed with madder, weld, and logwood, for example, are determined by the chemical nature of the mordant used Table 95 lists hues obtained when dyeing with the same dye but with different mordants. 

Hematein and hematoxylin are known as the main components of logwood, but other characteristic colourants are also present in its preparations, e.g. tannins and... 

K. Pawlak, M. Puchalska, A. Miszczak, E. Rosloniec and M. Jarosz, Blue natural organic dyestuffs from textile dyeing to mural painting. Separation and characterization of coloring matters present in elderberry, logwood and indigo, J. Mass Spectrom., 41, 613 622 (2006). 

Fig. 2.20 SQWVs (first scan) of weld (a, b) and logwood (c, d) immersed into 0.25 M HAc + 0.25 M NaAc (a, c) and that electrolyte plus 0.05 M AICI3 (b, d). Potential step increment 4 mV square wave amplitude 25 mV frequency 15 Hz [124]...

Fig. 4.5 Square-wave voltammograms for commercial Brazilwood (a) and logwood (e), and mixtures of both pigments containing 50% (b), 75% (c), and 85 % (w/w) (d) of Brazilwood, attached to paraffin-impregnated graphite electrodes. Electrolyte ...

Fig. 4.6 Variation of the peak currents for peaks at +0.20 (squares) and at +0.65 V (rhombs) with the percentage of Brazilwood in square-wave voltammograms for Brazilwood plus logwood mixtures in contact with a phosphate buffer. Conditions are as in Fig. 4.5. Here, identical amounts of sample were transferred to the parafiSn-impregnated graphite electrode...

With hydrous zinc oxide there is a slight adsorption of yellow alizarinic acid and purple sodium alizarate. A variation in the degree of acidity with stannic oxide and zinc oxide will give all variations of color between yellow and purple, while the presence of alumina introduces a red. This accounts for the fact of alizarin being what is called a polygenetic color, because the color varies with the nature of the mordant. Other examples of this class are said to be cochineal and logwood but we have not yet studied these dyes. 

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