The founder of stone conservation and restoration company Stonehealth has warned specifiers and building owners of the risk of using imitation machinery.

Brian Crowe said that since the latest iteration of the company's Doff III machine launched earlier this year, a photo has surfaced showing an alternative machine being used on a project carrying a Doff sticker in an attempt to appear authentic.

“For the past 30 years we have created a reputation as the leaders in our field,” said Mr Crowe. “So while in a way it’s a compliment to have impostors pretending to be us, it’s not one that we welcome.

“What we are often finding is that our products are specified for projects but then, to save costs, inferior machinery is used by unqualified personnel. While this is a serious issue for our business – we risk suffering damage to our brand – we have a major concern about the impact of our heritage buildings.

“If damage is done, it’s irreversible. If you remove the surface of stone or break then you can’t get it back.”

Mr Crowe, who founded Stonehealth in 1989, said education was key to ensuring that buildings continued to be properly treated.

“Our intention is to make architects, surveyors and other specifiers – including conservation officers – aware of people working with something different to what’s been specified or approved. Any queries on whether the contractors and machines are genuine should be directed to us. We know where our machines are and the personnel who are trained to use them.

“We place great emphasis on training the contractors who use our equipment, as well as ensuring that our machines are properly specified.

“Our reputation has been earned over decades of innovation and care for our industry and we won’t tolerate abuse of it, or the risk of unsatisfactory results from impostors harming the likelihood of our products being specified again.”

To help ensure that only bona fide contractors are considered and awarded contracts, Stonehealth has set up its Approved Rosette Contractors Scheme.

Approved contractors must meet stringent criteria including: full training in use of Stonehealth equipment, reviewed every year; use of only genuine Stonehealth parts and materials; annual inspection and servicing of machinery by Stonehealth; provision of at least two customer testimonials per year to maintain Rosette status.