Changes to the way glass is used during the past 10 years have put pressure on firms involved in the industry.
While glaziers that can replace a broken window with a handful of putty are still relatively easy to find, those that can specify and supply glass as a building product, to fabricate walls, floors and staircases, are thin on the ground.
Debbie Paul, chief executive of the Joiner Industry Training Association, which administers glazing apprenticeships, says in the 1990s apprenticeships were not really promoted and that during that time architecture changed to include glass in all aspects of building construction - all of a sudden it was not something you just looked through.
And she says the reason youngsters aren't taking up training options is because the industry has a low profile among school leavers.
"They don't know about it," she says. "People think the industry is just a glazier up a ladder replacing a sheet of glass with some putty. But our glaziers never touch putty. Today, glass is such a versatile product because it is not heavy on maintenance. It can now be used in places that ten years or so ago were unthinkable."
Paul says the government's introduction of double glazing alone has led to new machines being imported to fabricate window units - but finding people to operate them has been difficult. With the glass industry developing here, firms are unable to simply lure people from competitors - the people just don't exist.
"There is a lot of pressure on the glass industry at the moment and it is a well-paid industry," she says. "People can choose to work inside fabricating or outside as glaziers."
Stewart Knowles, CEO of the Glass Association of New Zealand, says with the tailing off of construction projects due to the downturn in the economy, demand for skilled labour in the glazing industry has subsided, but that pressures still exist in some parts of the industry.
"It has certainly been a very difficult situation for a long time to find skilled people to do work. Certainly some firms using new machinery will be in the thick of it - they will really be struggling as they need decent staff that can run processing machinery.
"There are various levels that you can work at in the industry. There's your glaziers replacing a window that a ball went through, and then there are your more specialised people doing construction with offices and high-rise buildings - and this is where the shortages are."
Marijke van Nooijen is general manager at Glass Relate and says finding staff with the ability to accurately measure glass to the exact millimetre required is harder than people think.
"No longer can a short piece of glass be hidden under putty. With frameless installations, glass has to be cut exactly right. If it is one or two millimetres out you've got a complaint because it needs to line up perfectly."
Van Nooijen says the company works closely with architects specifying which glass can be used where.
There are many rules covering schools, homes, business premises and public places. The high level of expertise that is now required is not something the average old-school glazier has, she says.
"And this is another point of difference to what the industry used to do. We even have toughening furnaces where we process imported glass."
Van Nooijen says the glass trade is still changing and people working in the industry need far more skills and education than they used to. But her firm is playing a part in developing the people the industry needs. At any one time, she employs three apprentices.
"It is up to glass companies to take on people and train them - most young people are keen to be trained."
One of Glass Relate's apprentices is Andrew Ball. He has almost completed his four-year apprenticeship at the firm and says he was blown away with the things that can be done with glass.
"When I started I thought the job would just involve putting glass in a wooden frame. Today you can make a building made entirely from glass - including its roof. I have been involved in installing glass bridges, a glass staircase, pool fences - people are using glass for everything now."
One of Ball's recent projects was erecting a glass wall outside a client's home to block the wind from whistling around the property.
"Once the glass was in place we had a sandblaster come and create wonderful designs and pictures of knights on horses in the glass - it looks great," he says. "I love what I do."