Basic blue 9 also called methylene blue, is a type of very popular dye. It is stable in air, but it is sensitive to light. It is economical and it has excellent brightness.
It is yellow green in concentrated sulfuric acid and turns blue after dilution. In the concentrated nitric acid, it was gray-green. The dye solution with sodium hydroxide was purple with dark purple precipitation. Adding hydrochloric acid did not change. Dyed in silk green light blue, tungsten light green dark. Dyed with tannin mordant cotton cloth green bright blue, tungsten light green.
TRADE NAME:Methylene blue 2B,Basic Lake Blue BB,Basic Blue BOC,Basic Blue 4RF,Basic Blue BO,Methylene violet
Economical and easy to dose for both batch and continuous processes
Basic Blue 9 used in dyeing fibers, silk, wool and linen. it is soluble in ethanol, chloroform, slightly soluble in pyridine, and it is insoluble in ethyl ether.
| Light Fastness | 5-7 |
| Perspiration Fastness(fading) | 5 |
| Perspiration Fastness(stain) | 3-4 |
| Soaping(fading) | 3-4 |
| Soaping(stain) | 5 |
Fiber | Item | light fastness | Flooding | Soaping (40℃) | Perspiration | Rubbing | Ironing | Sulfuric acid resistant
| Acetate resistant | Alkali resistant | |
Dry | Wet | ||||||||||
Silk | Sample change | 1 | 3~4 | 2~3 | 3 | — | — | 4~5 | 3 | 4 | 1~2 |
white silk stain | — | 1 | 1~2 | 1 | — | — | — | — | — | — | |
white cotton stain | — | 2~3 | 3 | 1~2 | 3~4 | 2~3 | 5 | — | — | — | |
The dye’s uptake and final hue are pH-dependent: mildly acidic to neutral baths favor uptake on protein fibers, while strongly alkaline conditions can shift shade and reduce affinity. For consistent results, control the dye bath pH and document the pH used for each recipe.
Basic Blue 9 (methylene blue) should be handled following standard chemical safety procedures: avoid ingestion, inhalation, and prolonged skin contact; use gloves and eye protection; provide local exhaust if powders are handled. Refer to the product SDS for specific hazard classifications and first-aid measures.
Shade shifts can result from differences in fiber lot, pH, temperature profile, liquor ratio, or auxiliaries. Documenting and replicating critical process parameters (bath pH, temperature ramp, liquor ratio, dye dosing method) and using production-scale trials reduces shade variance.
