"Epoxy coated" on a delivery challan is a claim, not a specification. Two bars can carry the same description and age quite differently once cast into a foundation, because performance is decided by the coating's thickness, its continuity, and whether it survives being bent. All three are measurable, and all three are covered by a published Indian standard. That makes epoxy coating for TMT bars one of the few purchase decisions a buyer can verify rather than trust.
The standard behind the claim
Fusion bonded epoxy coated reinforcement in India is governed by IS 13620:1993, titled Fusion Bonded Epoxy Coated Reinforcing Bars: Specification, issued by the Bureau of Indian Standards. (Source: BIS, IS 13620:1993)
Conformity is not optional. Under the Ministry of Steel's Steel and Steel Products (Quality Control) Order, 2024, fusion bonded epoxy coated reinforcing bars must conform to IS 13620:1993 and be accompanied by a test certificate bearing the Standard Mark. (Source: Ministry of Steel, Government of India, Steel and Steel Products (Quality Control) Order, 2024)
That is the most useful thing a buyer can know: the certificate is something you are entitled to ask for. Note also what the standard governs. The coating, not the steel beneath; base bar properties fall under IS 1786:2008.
The numbers on the page
RustGuard's coating specifications sit against the BIS 13620:1993 requirements like this:
|
Parameter |
BIS 13620:1993 |
RustGuard |
|---|---|---|
|
Bare bar properties |
As per IS 1786:2008 |
Conforming to IS 1786:2008 |
|
Coating thickness |
100 to 300 microns |
175 to 300 microns |
|
Coating holiday |
6 per metre (max) |
5 per metre (max) |
|
Coating flexibility |
120 degree bend using 10D |
120 degree bend using 8D and 10D |
Three of those rows repay a closer look, because each measures something different.
Thickness sets the clock
Thickness is measured in microns and sets how long the barrier lasts before moisture and chlorides get through. Too thin, and the film offers little protection. Too thick, and it turns brittle and cracks when bent, which is why the standard sets a ceiling as well as a floor.
So the specified range matters more than the word "coated." A Rust Guard TMT bar is specified from 175 microns upward, above the standard's floor of 100.
A single break defeats the barrier
A holiday is a discontinuity in the coating: a pinhole, a scratch, a missed patch leaving bare steel exposed. The term sounds harmless; the defect is not. Corrosion needs only an opening, so a coating 99 percent intact can still corrode at the one percent that is not.
This is why the standard counts them per metre rather than treating coating as pass or fail. Detection uses an electrical instrument that finds breaks invisible to the eye, and a lower permitted count means a tighter tolerance.
Bend performance is where coatings fail
A coating that is perfect in the plant is useless if it cracks the first time a bar is bent into a stirrup. This test reflects site conditions most closely, and it separates well-applied coatings from poor ones.
The specification calls for a 120 degree bend around a 10D mandrel. The Rust Guard TMT bar is tested at 8D as well, a tighter radius that strains the coating more than required.
Asking the right questions
Specifications only help if you use them. Ask for the test certificate. Ask what thickness range the product is specified to, not just whether it is coated. Ask whether holiday detection and bend testing are done batch by batch.
Every figure above, plus the comparison of coated and uncoated bars across salt spray, impact and bond testing, is published on the Rust Guard TMT bar product page. Thickness, holiday detection and bend testing are done in Captain Steel's own laboratory, and a test report goes out with the consignment. The certifications page lists the certificates; the brochure carries the full technical detail.
That is the standard any coated bar should be held to, RustGuard included. Choosing epoxy coating for TMT bars sensibly is less about the right adjective than about asking for the numbers and checking them.
