Acid Orange II

Acid Orange II, also known as C.I. Acid Orange 7 (C.I. 15510), is an orange acid dye used for wool and silk dyeing, with additional applications on nylon, leather and paper that should be assessed according to the material and process. It is valued for bright, even color. Tianjin Leading supplies an Acid Orange II grade identified as CAS 633-96-5, with published 100% strength, moisture ≤5.0% and water-insoluble matter ≤1.0%.

If you are qualifying a new supplier or replacing an existing Acid Orange 7 grade, send us your target substrate, approved shade, required quantity and testing criteria. These details help establish whether the offered grade meets your production and purchasing requirements.

What Is Acid Orange II?

Acid Orange II is  C.I. Acid Orange 7 (C.I. 15510). Our published grade is an orange-red powder that dissolves in water to form a reddish-yellow to orange solution, with a reported water solubility of around 40 g/L at 25°C. The dye is used where buyers need to develop or match an orange shade on a suitable material.

Acid Orange II is generally known in the industry for bright, even color and easy application, though its fastness properties (light, soaping, rubbing) are more moderate than some other acid dye grades.

The name Orange II may also appear in chemical and laboratory listings. For an industrial dye purchase, confirm the offered strength grade, approved shade and intended application rather than relying on the shared name alone. 100% strength is the grade shown in our product specification.

Acid Orange II is part of our wider Acid Dyes range, and is also used to produce Acid Black ATT when blended with Acid Black 10B. Buyers sourcing multiple colors can review the range alongside this specific grade.

Is This Grade Suitable for Your Material?

The same dye name may appear across several industries, while the required results differ by substrate. Confirm the intended material before selecting Acid Orange II for a production order.

Wool Dyeing

Wool is a principal application described for Acid Orange II. For a new project, assess the orange shade and levelness on the actual wool material. For replacement purchasing, compare the new sample against the approved dye at the same color depth and under representative dyeing conditions.

Silk Dyeing

Silk is also a principal application. Buyers should evaluate the final shade on the intended fabric, then check the fastness requirements of the finished product. Provide a physical color reference or dyed sample if the new supply must match an established range.

Nylon and Polyamide

Nylon and polyamide materials are also listed applications, typically dyed in a formic acid bath. Confirm the exact substrate, bath conditions and required fastness before approving the grade.

Direct Printing

Beyond dye-bath application, Acid Orange II can also be used for direct printing on wool, silk and nylon fabric. If printing rather than dyeing is your process, mention this in your inquiry, as print paste formulation and fixation differ from standard dye-bath conditions.

Leather and Paper

Leather and paper coloring are additional listed uses. Share the substrate, processing method and target shade before ordering for either application. A trial on the intended material is the appropriate basis for approval.

Indicator and Biological Coloring

Acid Orange II is also referenced in laboratory contexts as a pH indicator and for biological/histological staining use. This is a distinct application from industrial dyeing — if this is your intended use, specify it clearly, as required purity and documentation may differ from a standard industrial dye grade.

Not Recommended for Direct Cotton Dyeing

Acid dyes such as Acid Orange II are formulated to bond with protein fibers (wool, silk) and polyamide fibers (nylon) through their amino groups. They are not effective for directly dyeing pure cotton or other cellulose fibers, which lack the same binding sites. If cotton or cotton-blend dyeing is your goal, a direct or reactive dye is generally more suitable — contact us and we can help point you toward the right product in our range.

Shade and Color Fastness

Packaging and Order Information

The product description lists 25 kg bags and iron drums.MOQ is 500kg.

Frequently Asked Questions

Is Acid Orange II the same as Acid Orange 7?

On this page, Acid Orange II is listed as C.I. Acid Orange 7 (C.I. 15510), CAS 633-96-5. For purchasing approval, also check the offered strength grade and shade against your standard.

What materials can this grade be used for?

Our product information describes wool and silk dyeing as the main applications, with nylon (formic acid bath), direct printing, leather and paper as additional uses. Confirm the actual substrate and required results through a sample trial before approving a bulk order.

Can Acid Orange II be used to dye pure cotton?

Not directly. Acid dyes like Acid Orange II are designed to bond with protein fibers (wool, silk) and polyamide fibers (nylon), not cellulose fibers such as cotton. If you need to dye cotton or a cotton blend, ask us about a suitable direct or reactive dye instead.

Can this industrial dye be purchased for food coloring?

No. This page offers an industrial dye grade and does not establish food-use suitability. Acid Orange 7 has historically appeared in food-dye references, but its use as a food colorant is now restricted or banned in many countries. If your project requires a food-grade colorant, that is a separate product category with its own regulatory documentation — please specify this requirement separately.

What is the molecular formula and weight of Acid Orange II?

Acid Orange 7 is commonly referenced as C16H11N2NaO4S with a molecular weight of approximately 350.3. Request our current COA if you need confirmed figures for documentation purposes.

Request an Acid Orange II Quote

Tell us the material you need to dye, your target orange shade and the quantity you plan to purchase. If you are replacing an existing Acid Orange 7, include the current grade or a dyed sample and your required fastness standard. We can then discuss the offered specification, evaluation needs, packaging and quotation for your order.