Attempts will be made this weekend to seal cracks around the ventilation shaft at the Pike River Coal mine and stop gases leaking out.
Foam that expands to 35 times its original volume and hardens within about five minutes will hopefully create an effective seal that will allow the GAGand Floxal machines - which are pumping water and nitrogen into the mine - to operate more efficiently.
Temperatures and methane gas levels inside the mine continue to fluctuate, hindering attempts to get into the West Coast mine and recover the bodies of 29 men killed in a series of explosions since November 19.
Operation commander, Superintendent Gary Knowles, said the sealing work was a critical next step in the process towards stabilising the mine, and technicians from Australia would undertake the work.
The expanding Rocsil Foam had been used effectively in coal mines in Europe and Australia, he said.
A second sealing product, Fenoflex, would be used if the foam did not work.
Mr Knowles said the sealing was specialised work which was complicated by the challenging terrain. The work was also weather dependent.
Mr Knowles said the GAG and Floxal teams worked throughout the Christmas period.
"(They) have worked long hours and carried out crucial work in terms of the effort to stabilise and make the mine safe," he said.
Both machines are still operating but both temperatures and gas levels being recorded from the mine continue to fluctuate.
Earlier this week Mr Knowles said temperatures in the mine had fluctuated by more than 100degC. The lowest had been in the 30s.
