I roto i te wāhanga whakapūpū o te umanga pepa hou, ko te mata wiri mō te mīhini pepa he taputapu matua mō te purenga me te tātaritanga o te penupenu. Ka pā tika tōna mahi ki te kounga o te hanga pepa me te whai huatanga o te whakaputa, ā, he whānuitia te whakamahinga i roto i te wāhanga maimoatanga o mua o ngā penupenu rerekē pērā i te penupenu rakau me te penupenu pepa para.

Mō te kaupapa mahi, ka whakaputahia e te mata wiri te wiri ahunga mā te motuka hiko e taraiwa ana i tētahi poraka rerekē, ka meinga te anga mata kia taraiwa i te mata mata kia mahi i te nekehanga auau teitei, iti te whānui. Ina uru te penupenu ki te tinana mata mai i te tomokanga whāngai, i raro i te mahi a te wiri, ka haere ngā muka whai tohu (iti rawa) e tutuki ana i ngā whakaritenga tukanga mā roto i ngā āputa mata mata ka tomo ki te tukanga e whai ake nei; ko ngā toenga penupenu, ngā poke, me ētahi atu (rahi rawa) ka haria ki te putanga tuku para i te taha whakarara o te mata mata ka tukuna, ā, ka oti te wehenga me te purenga o te penupenu.

Mō te hoahoa hanganga, e rima ngā wāhanga matua o te mata wiri: tuatahi, ko tetinana mata, e mahi ana hei tinana matua mō te pupuri me te wehenga o te penupenu, he mea hanga te nuinga ki te maitai kore waikura hei whakarite i te ātete ki te waikura; tuarua, ko tepūnaha wiri, tae atu ki te motuka, te poraka rerekē me te puna mimiti-ru, i roto i ēnei ka taea e te puna mimiti-ru te whakaiti i te pānga o te wiri ki te turanga taputapu; tuatoru, ko temata mata, hei wāhanga tātari matua, ka taea te whiriwhiri i te mata whatu maitai kore waikura, te mata poka, me ētahi atu, kia rite ki te momo penupenu, ā, me whakatau te maha o ōna mata me ngā whakaritenga momo pepa; tuawhā, ko tetaputapu whāngai me te tukunga, ko te tomokanga whāngai he mea whakarite ki tētahi ārai hei karo i te pānga tika o te penupenu ki te mata mata, ā, me ōrite te putanga tukunga ki te teitei whāngai o ngā taputapu e whai ake nei; tuarima, ko tetaputapu tuku, ko ētahi mata wiri nui he taputapu whakaiti tere hei whakahaere tika i te auau wiri.

I roto i te whakamahinga mahi, he nui ngā painga o te mata wiri: tuatahi, he pai te horoi, ka taea e te wiri auau teitei te karo i te aukati i te mata mata, me te whakarite kia neke ake i te 95% te tere o te whakawhiti muka; tuarua, he watea te whakahaere, ka taea te whakarerekē ngāwari i te auau wiri mā te whakarerekē i te tere o te motuka kia urutau ki ngā kukū penupenu rerekē (ko te kukū maimoatanga he 0.8%-3.0%); tuatoru, he iti te utu tiaki, he tere te wetewete o te mata mata, ā, ka taea te whakapoto i te wā whakakapinga ki raro iho i te 30 meneti, ka whakaiti i te wā kore mahi o ngā taputapu.

I te whanaketanga o te umanga pepa ki te "tino whai hua, te penapena pūngao me te tiaki taiao", ka whakahoutia tonutia te mata wiri. Hei tauira, ka whakamahia te pūnaha whakahaere tahuritanga auau atamai hei whakatutuki i te whakarerekētanga aunoa o ngā tawhā wiri, ka arotauhia rānei te hanganga mata mata hei whakapai ake i te tika o te tirotiro o ngā wāhanga pai, kia tutuki ai ngā whakaritenga pakari o te pepa kounga teitei me te hanga pepa motuhake mō te parakore o te penupenu.