The atlas restorer

The atlas lay open under a row of cool lamps. Mara slid a sheet of support paper beneath the torn coastline, then stopped to check that its fibres followed those of the original page. She did not press the repair flat until the paste had settled. When I asked why such a narrow strip mattered, she placed an untreated offcut beside the repaired edge and invited us to lift both. One curled at once; the other stayed level. Her answer lasted less than a minute, but nobody asked her to repeat it.

From the passage, select one phrase showing that Mara carries out the repair with care and one phrase showing that her explanation is effective. Explain what each phrase suggests.