What is Sodium Tetraborate Decahydrate CAS 1303-96-4?

It is the refined sodium borate commonly called borax decahydrate, with the typical formula Na2B4O7·10H2O. This white crystalline grade contains about 36.5-38% B2O3 and differs from pentahydrate because it carries ten water molecules per formula unit.

Why is borax decahydrate used as a flux in soldering, brazing, and metal recovery?

At high temperature it forms a glassy melt that dissolves metal oxides and shields the metal surface from further oxidation. This improves wetting and flow of solder or braze alloy and helps recover precious metals from slags and concentrates.

What pH and water solubility should I expect?

A dilute aqueous solution of sodium tetraborate decahydrate is mildly alkaline, typically around pH 9.2-9.5 in the specification range shown above. Water solubility is about 50-60 g/L at 20 degrees C, so warm water or mixing time may be needed for higher concentrations.

Is this borax decahydrate suitable for food or cosmetic applications?

No. This product is labeled Industrial Grade, so it is not offered as a food additive or cosmetic ingredient. Applications requiring food, pharmaceutical, or personal-care compliance should use the appropriate regulated grade and confirm the required purity and documentation.

Sodium Tetraborate Decahydrate CAS 1303-96-4

Sodium Tetraborate Decahydrate, also called borax decahydrate or sodium borate decahydrate, CAS 1303-96-4, is an industrial-grade white crystalline material supplied as a flux, pH buffer and detergent builder. Confirm the required grade and specification, then request a quotation with COA/TDS/SDS for bulk supply.

CAS: 1303-96-4
Synonyms: Borax decahydrate, Sodium borate decahydrate, Disodium tetraborate decahydrate, Borax 10H2O, Sodium biborate.
Einecs: 215-540-4
Molecular Formula: Na₂B₄O₇·10H₂O
Grade: Industrial Grade
Package: 25kg/bag, 50kg/bag, or 1000kg jumbo bag.

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Product Description

Sodium Tetraborate Decahydrate CAS 1303-96-4 is a white crystalline borate, also known as borax decahydrate or sodium borate decahydrate, with the formula Na₂B₄O₇·10H₂O and EINECS 215-540-4.

Synonyms: Borax decahydrate; Sodium borate decahydrate; Disodium tetraborate decahydrate; Borax 10H₂O; Sodium biborate.

CAS: 1303-96-4.

Molecular formula: Na₂B₄O₇·10H₂O.

It appears as a white crystalline powder or granules.

A dilute aqueous solution is mildly alkaline, typically around pH 9.2-9.5.

At high temperature it forms a glassy melt that dissolves metal oxides and shields the metal surface from further oxidation.

This fluxing action improves wetting and flow in soldering, brazing and metal recovery.

It is used in borosilicate glass, fiberglass and ceramic glazes, as a flux in metallurgy, and as a pH buffer and water softener in detergents.

The typical boron trioxide (B₂O₃) content is about 36.5-38%, and sodium oxide (Na₂O) about 16.0-16.5%.

Water solubility is roughly 50-60 g/L at 20 °C.

It can slowly lose water of crystallization in very dry or warm conditions, so containers should stay tightly closed.

Store in a cool, dry, well-ventilated area away from moisture and heat.

Protect from moisture and keep containers closed when not in use.

Confirm appearance, assay, B₂O₃ content, pH, insoluble matter and grade as required.

Use suitable eye and skin protection during handling, and wash skin contact with soap and water.

Confirm packaging with the requested quantity and destination requirements.

The page is an RFQ entry point and does not state stock, price, MOQ or fixed lead time.

For an RFQ, state the intended application, required grade, quantity, packaging, destination and document needs.

FAQ - Technical & Supply Chain

Q:
What is Sodium Tetraborate Decahydrate CAS 1303-96-4?

A: It is the refined sodium borate commonly called borax decahydrate, with the typical formula Na2B4O7·10H2O. This white crystalline grade contains about 36.5-38% B2O3 and differs from pentahydrate because it carries ten water molecules per formula unit.
Q:
Why is borax decahydrate used as a flux in soldering, brazing, and metal recovery?

A: At high temperature it forms a glassy melt that dissolves metal oxides and shields the metal surface from further oxidation. This improves wetting and flow of solder or braze alloy and helps recover precious metals from slags and concentrates.
Q:
What pH and water solubility should I expect?

A: A dilute aqueous solution of sodium tetraborate decahydrate is mildly alkaline, typically around pH 9.2-9.5 in the specification range shown above. Water solubility is about 50-60 g/L at 20 degrees C, so warm water or mixing time may be needed for higher concentrations.
Q:
Is this borax decahydrate suitable for food or cosmetic applications?

A: No. This product is labeled Industrial Grade, so it is not offered as a food additive or cosmetic ingredient. Applications requiring food, pharmaceutical, or personal-care compliance should use the appropriate regulated grade and confirm the required purity and documentation.
Q:
How should Sodium Tetraborate Decahydrate be stored to prevent caking?

A: Keep it in a cool, dry, ventilated area and keep the package tightly closed. The decahydrate can slowly lose water of crystallization in very dry or warm conditions, so protecting it from heat and moisture swings helps preserve its free-flowing crystalline form.

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