Prestocure High Pressure Sap Displacement HPSD

The business known as Sisson Kayaks Ltd or before 1988, Sisson Industries Ltd actually started in 1972 – in the home garage – producing light engineered components for George Mason (the kind man), also known as (Cecil) C.G.W. Mason (the acclaimed industrial chemist)♦. George held patents for his ‘Perfusion’ brand ‘Improved Apparatus’ High Pressure Sap Displacement (HPSD) equipment.

Perfusion HPSD pamphlet.

Low pressure Sap Displacement treatment of freshly felled logs was perfected in Egypt thousands of years ago. At low pressure the process is very slow. The application of high pressure hastens the process and concentrates the level of treatment. George was THE true pioneer of HPSD. In the seventies I did not truly understood what motivated George. Thanks to the Internet, in 2018, I now understand his mission. George was trying to solve a widespread farmers problem created by the creosote shortage caused by the closing of coal fueled gas-works. George had for a decade been seeking to create an alternative on-farm Pufusion treatment option for farmers to use.

Reportedly, whichever engineering shop George entered,  his plans were handed to the apprentice. The plans were over-complicated – a tradesman’s simplification was required – and the end-operational-production was usually overlooked. Nothing worked. George became a frustrated man.

George and I were introduced by George’s sister – our Nelson next door neighbour. I owned some light engineering equipment and set out to assist George to commercialise his dream. My day-job was Service Manager for M S Motors, Ford Dealers in Nelson. My work for George was a weekend hobby.

Only now in 2018 – using Google search – do I (at last) understand George’s plan For at least twenty five years he had been searching for ways that would enable farmers to extend the life of their own timber thinning – to make their own posts and poles. I wish I had better understood George in 1974.

In early 1974 I resigned my job at Meager Salary (5 broken employment promises) Motors and decided to catch up with George’s back-log of work, before looking for a new job. George poured more work in. That new job was never to be! After the machining and production of many stainless steel components, final assembly was impossible. George had been let down (again) by the fibreglass factory he had arranged to produce the composite pressure cap bodies. Enter fibreglass into the Sisson home workshop – and a new hobby kayak (just for me) becomes a possibility. Simply how it happened.

C G W (George) Mason. Customer #1, who wrenched me from automotive service, into the manufacture of composite products.

Perfusion HPSD was commercialised within 12 months with quite a few plants exported. However, the Perfusion pressure cap design included many small parts – that were expensive to manufacture and assemble. In the forest settings these same parts broke due to each locking pin needing to be individually engaged – sometimes with a hammer! . The lower pin was too often overlooked – the adjacent pins failed under the huge pressure forces.

What to do. HPSD certainly worked. How to make a more durable – and cheaper pressure cap? I had a light-bulb (literally) inspiration

All 12 pins engage the aluminium sleeve simultaneously. Simple twist.

and loosely discussed my ideas with George. We agreed that I should develop the prototype myself – patent it – demonstrate it to George – and he would write me a sizeable cheque to purchase the patent. My chosen name was Prestocure HPSD.

Nine months later, just one week before the patent became valid, my customer, mentor and friend George passed away.

I became the owner of a venture that required capital to succeed. TNL Group (huge company then) were aware of my ‘improved apparatus’ invention and NZ patent. TNL Group purchased the offshore rights to the Prestocure patent – and proceeded to operate a plant.

The object was to gain full H3 approval from the NZ Timber Preservation Authority. The process worked. All of the scientific testing proved positive. Approval to treat timber to H3 (then C3) Standard was granted.

Meanwhile Sisson Industries sold Prestocure HPSD laboratory sets to Dow Chemicals and the NZ Forest Research Institute. Many farmers purchased Prestocure HPSD equipment. Zero Prestocure cap failures reported. No small parts to break. The fibreglass pressure caps were tested to thirty five Bar (500psi) – well beyond the possible pressure that a log would sustain – 13 Bar (200psi)

Resulting in

HPSD sap flow in pine – sweet nectar!

Followed minutes later with this

HPSD CCA treatment complete after 10 minutes

Or viewed on a faster flowing eucalyptus hardwood

eucalyptus treated in 3 minutes

The aluminium sleeves come in 125mm, 140mm and 150mm sizes. The cap is usually fitted at the small end (tree top) of the log.

The ‘O’ ring seals to the fibreglass cap whilst the twelve inner-cap pins lock onto the sleeve with a twist.  Shown is the inflatable ‘primary’ seal. The secondary timber crushing seal – not shown.

The TNL Group assisted with some NZ marketing

Article in TNL paper outlining Keith Owen’s efforts

So what happened? The farmers market perceived by George evaporated. Native trees could no longer be felled without consent. Tighter environmental laws made CCA preservative difficult for farmers to access. TNL baled out – but their involvement made them added after-tax revenue. Muldoon had set up some crazy 150% tax deductability export incentives for businesses with high tax bills. Sisson Industries Ltd simply resorted to  manufacturing products that the current customers ordered – mostly kayaks. Prestocure HPSD simply withered away by the mid 80’s due to lack of marketing and customer enquiry.

Forty years later I wonder if Prestocure HPSD would be better used to farm shiitake mushrooms! Make the logs rapidly rot using select fungi!

OK – time to come clean – Sisson Industries Ltd started a fibreglassing section to manufacture Perfusion HPSD caps – not kayaks. The kayaks happened later – by accident.

Why is this story relevant in 2018? Simple – in parts of Asia there is renewed interest in HPSD (as there should be) but it seems that lack access to decent reliable pressure caps is a problem.

I have a huge (dead) stock of Prestocure caps. Plus the tooling to manufacture more.

So – if you are an Asian HPSD timber treatment operator – with continued frustration due to broken equipment – email me here at

I may be able to assist.


Q      Does HPSD have a future.

A      Absolutely. Firstly we need to see the development of environmentally safer preservative chemicals – than the effective-but-evil Copper Chrome Arsenate (CCA). Ivan Watkins Dow (Dow) thought they had discovered such a safe preservative with their ‘ProteQU’ product. Scientifically – their workers could not understand why it worked. The passage of time proved – it did not work. A safe-to-handle preservative will become available at some time in the not too distant future.

Grahame Sisson     –    March 2018

PS: – I will never know why Cecil asked me to call him George. He seemed to prefer George for commerce. Ces for science. Cecil for family.

CGW Mason – scientist and inventor of the Perfusion Timber Treatment Cap.

♦ Cecil George Wilmot Mason was acclaimed for his science relating too: –

(a) increasing the generated gas quantity from a given tonnage of coal (b) Sustainable power generation in large tropical forests (c) Various United Nations projects aimed at better quality of life in emerging countries (d) Ground breaking science in the field of NZ 1950’s timber preservation (f) Making mankind aware of High Pressure Sap Displacement and its portable benefits. (G) Influential member of the New Zealand Association of Scientific Workers (see below) (H) Unsuspecting founding client of the largest composite kayak manufacturer in the Southern Hemisphere – Sisson Kayaks.

Contact Grahame

For all enquiries and orders please contact me directly:

Phone: 027 2755 499


Phone: 027 2755 499Email:

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