More small steel mesh-makers are using proper lab testing of their product than at the big end of the market.
Among the big three makers, only Fletcher Reinforcing has been forthcoming about how it tests mesh, including the critical seismic grade that goes into slab floors and some precast concrete walls to help them withstand big earthquakes.
Fletcher Reinforcing - which is part of Fletcher Building - gets its mesh and other testing done independently at steelmaker Pacific Steel's lab.
That lab is not accredited to test mesh but does get regular audits from Australasian accrediting body ACRS, which tests random samples to see if the results match up.
The number one player, United Steel, said it had no comment to make.
When RNZ rang to question this, United's executive director Richard Anyon said mesh testing was not as simple as the media was portraying it.
When asked if United used an independent accredited lab for testing, he said it was "absolutely not any of Radio New Zealand's business".
Number two player, Steel and Tube has confirmed it uses its own in-house testing, which is not required to be audited.
That testing is under question - the company passed a batch of mesh with ductility scores of between 10.5 and 12.5 percent.
The pass level is 10 percent.
But a sheet of that mesh, tested independently by top lab SGS, returned scores between just 3.6 and 6.8 percent.
The SGS results would not be good enough for Colin Fenwick of Fenwick Reinforcing in Christchurch
"It's nowhere near where it should be, but it wouldn't wear with us, having a test certificate with those sort of results on it," Mr Fenwick said.
Mr Fenwick was unusual among the minnow mesh makers - the only other two, which RNZ spoke to, were incredibly reluctant to say anything.
But Mr Fenwick wanted all the companies to have to use independent accredited lab testing, which he estimated adds 50 cents to the cost of a $75-$120 sheet of mesh.
"We have actually questioned some of the product. Some of our test results come out at 99 percent, it's a failure, if it comes at 100 percent it's a pass. I guess that's where you have got to draw the line in the sand. We have had some recently which hasn't been where it should be and we have basically put that aside."
Like Mr Fenwick, who says his firm regularly sends mesh samples off for testing to the accredited Holmes Solutions lab, the other small players - Anchor Wire, in Auckland, and Reinforcing Steel & Mesh in Napier - also say they test at independent labs.
RNZ has so far not confirmed that.
Steel and Tube, asked about the poor SGS test results, said it was uncomfortable commenting based on third-hand information and a report it had not seen.
RNZ has chosen not to provide a copy of the test certificate, redacted or otherwise, to Steel and Tube, but had offered to talk the company through all the numbers on it.
The Ministry of Business, Innovation and Employment said it had not seen the SGS test certificate either but, generally, if a first test failed, then more tests needed to be done to conclusively determine whether a product was up to the standard or not.
Two other mesh suppliers, the big Euro Corporation and small Brilliance Steel, have been barred from the seismic mesh market after their product failed Commerce Commission tests this month.
The dispute around that, and the commission's wider testing of a range of companies' mesh, is still going on.