Industrial optimization powerhouse

From reducing melting temperatures in fiberglass production to inhibiting corrosion in fuel additives, Optibor® has a multitude of uses across industries.

Optibor boric acid is theoretically composed of boric oxide and water. It can be purchased as granules or as a powder, both of which are stable under normal conditions, free-flowing, and easily handled by means of air or mechanical conveying. In solution, the product is mildly acidic.


Boric Acid  
Orthoboric Acid

Made In

USA and France

What can Optibor boric acid do for you?

The key to its usefulness is its simplicity—Optibor boric acids are a pure, multifunctional source of boric oxide.

Optibor improves industrial process and product

In manufacturing of fiberglass, borosilicate glass, and industrial ceramics, Optibor:

  • Acts as a flux and network former 
  • Assists in the melt of fiberglass and borosilicate glass  
  • Initiates glass formation at low temperatures 
  • Reduces viscosity and surface tension in ceramics 
  • Speeds the development of smooth, even glaze surfaces 
  • Ensures a thermal fit between ceramic glaze and body 
  • Increases refractive index 
  • Enhance strength, durability, and scratch resistance in enamels 
  • Facilitate lead-free formulations 

Optibor enhances industrial formulations

Optibor improves effectiveness of flame retardants and adhesives:

  • Changes the oxidation reactions and promote char formation—inhibiting combustion in cellulose material 
  • Reduces the flammability of cellulose insulation, wood composites, and mattress cotton batting 
  • Strengthens metal alloys and steel 
  • Improves the tack and green strength of casein- and dextrin-based adhesives by cross-linking conjugated hydroxyl groups 
  • Acts as a pH buffer and as a cross-linking agent to emulsify waxes and paraffins 
  • Catalyzes oxidation of hydrocarbons and increase the yield of alcohols by forming esters that prevent further oxidation of hydroxyl groups to ketones and carboxylic acids 

Optibor provides protective properties in heavy industry

The boric acid in Optibor is needed across such diverse applications as nuclear energy and metallurgy:

  • Absorbs thermal neutrons to help ensure the safety and control systems of nuclear power stations
  • Prevents oxidation of metal surfaces in welding, brazing, or soldering
  • Inhibits corrosion and stabilize thermal oxidation in aqueous and non-aqueous systems

When used in combination with a sodium borate (such as Neobor® or Dehybor® anhydrous borax), Optibor can adjust the sodium-to-boron ratio in glasses which require low sodium levels. This is important in borosilicate glass where boric oxide provides essential fluxing properties at low sodium and high alumina levels.


We’re here to help with your boron needs. 

Contact sales

Our regional sales teams are ready to help with your purchase

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Get technical support​

Your resource for borate-related technical and laboratory services across every industry

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​Request a sample

Get small quantities of our products to ensure you have what you need for your formulation or process

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Chemical and Physical Properties

Molecular weight: 61.83 g/mol

Specific gravity: 1.50 | Specific Gravity for Optibor Boric Acids Solutions (PDF)

Appearance: Free-flowing, white, crystal line granules or powder

Solubility: 5.46% boric acid by weight in saturated solution (water) at room temperature

Stability: Optibor is a stable crystalline product that does not change chemically under normal storage conditions. Wide fluctuations in temperature and humidity can cause recrystallization at particle contact points, resulting in caking. Care should be taken to avoid such fluctuations during product storage and to maintain the integrity of the packaging.

Bulk density: 55 lb/ft3 (881 kg/m3)

Angle of repose: 33°

Chemical Composition (Theoretical)

Boric oxide, B2O3: 56.30%

Water of crystallization, H2O: 43.70%

Containers: Grades may be available in bulk, IBCs, or small bags

Optibor reduces the linear coefficient of expansion in glass when silica is replaced proportionately with boric acid, facilitating a thermal fit in ceramic glazes and heat resistance in borosilicate glass.

When heated above 212°F (100°C) in the open, Optibor gradually loses water, first changing to metaboric acid (HBO2), of which three monotropic forms exist. These metaboric acid forms can volatilize at >600°C during heating, leading to potential losses of boron emissions. Dehydration stops at the composition HBO2 unless the heating time is extended or the temperature raised above 302°F (150°C). On continued heating and at higher temperatures, all water is removed, leaving the anhydrous oxide B2O3—an amorphous glass that begins to flow at 842°F (450°C). The amorphous form of Optibor TG has no definite melting point, softening at about 617°F (325°C) and becoming fully fluid at about 932°F (500°C).

Aqueous solutions of Optibor are mildly acidic, the pH decreasing with increasing concentration. Optibor’s sieve specification is U.S. sieve No. 20, with a mesh size of 0.850 mm and a retained guarantee of ≤ 2.0%. Optibor forms boric oxide above ~300°C, which softens and begins to flow between 350°C and 500°C.

Optibor is ideally suited to bulk transfer. Optibor shows little tendency to cake, except after prolonged storage or severe wetting.


Contact our sample fullfillment team.

We’re here to help with your boron needs.

Contact sales

Our regional sales teams are ready to help with your purchase

Learn More

Get technical support


Your resource for borate-related technical and laboratory services across every industry

Learn More

Request a sample

Get small quantities of our products to ensure you have what you need for your formulation or process

Learn More

Optibor in Action

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U.S. Borax, part of Rio Tinto, is a global leader in the supply and science of borates—naturally-occurring minerals containing boron and other elements. We are 1,000 people serving 650 customers with more than 1,800 delivery locations globally. We supply around 30% of the world’s need for refined borates from our world-class mine in Boron, California, about 100 miles northeast of Los Angeles.  Learn more about Rio Tinto.

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