PAT and Paul Bolster's analytical thought processes, honed over many years providing expert legal advice during their previous lives as lawyers, have made a smooth segue into ensuring the unqualified success of P. Guinane Pty Ltd, the couple's tea-tree plantation and production business at Chinderah.

Their fertile imaginations and methodical thinking have resulted in their business becoming one of the major players in the industry.

The Bolster's tea-tree plantation covers 106ha - there's 82ha at the home plantation along Tweed Valley Way and a further 24ha adjacent to Hanson's sand quarry in Cudgen.

They made the switch from sugarcane to tea-tree in 1993 and painstakingly planted 3.5 million seedlings. Not only do they reap their huge crop but the harvest is distilled on site, producing up to 35 tonnes of high quality tea-tree oil which is marketed both here and in the US, Germany and the UK.

Mr and Mrs Bolster had that grey matter working from the beginning - installing their own distillery and planting a productive variety of tea-tree to ensure maximum yield and financial return.

They planted normal tea-tree seedlings on the Cudgen farm but for the larger farm, opted for a scientifically enhanced seedling which was proving to yield thicker and therefore much more productive leaves.

And leaves are where it all happens in the production of tea-tree oil.

"When we harvest, we do it with hard love," Mrs Bolster said.

"The harvester cuts the stems of the trees - and in a good year they stand two metres tall - only a few centimetres from the ground, leaving only a short stalk, which amazingly, year after year, develops into another thriving tree.

"All the residue from the steaming process (in the distillery) is sold as mulch - we have had the one client who purchases it every year."

Planting high-yield seedlings, installing the distillery, finding someone to regularly purchase the distillery waste product as mulch and finding markets are just a few of the brainstorms which have ensured the success of P. Guinane Pty Ltd.

From the beginning, the Bolsters developed and defined a unique tea-tree product, Gelair.

Gelair is a biodegradable gel containing tea tree oil which is placed into an air-conditioning unit. When an air-conditioning unit operates normally, the gel vaporises in the air, releasing the tea tree oil.

The tea tree oil controls the mould and bacteria in the air handling units, ducts and rooms serviced by the air-conditioner.

Such was its success, the Bolsters accepted an "offer too good to refuse" and sold the business three years ago to a West Australian company.

That grey matter again! A proviso of the sale was the company use only the Bolsters' high quality tea-tree oil in production.

"Around 15% of our oil is sold to Gelair and the rest is marketed overseas," Mr Bolster said.