The woman, now in her mid-70s, denied being someone that youngsters would have been scared of.
She agreed there was "probably" a strict regime at Nazareth House in Aberdeen but told a probe she had not witnessed any abusive practices at the orphanage.
The Scottish Child Abuse Inquiry (SCAI), sitting in Edinburgh, is continuing its examination of four former children's homes operated by the Catholic congregation the Sisters of Nazareth in Scotland.
The inquiry has previously been told of various alleged abuses at the institutions.
The witness, who cannot be identified, said she worked at its homes in Aberdeen and Lasswade, Midlothian, from the late 1960s to the mid 1970s.
Senior counsel to the inquiry Colin MacAulay QC told the nun about evidence from another witness who described her as the children's "mother" at the Aberdeen home, tasked with looking after them and controlling them.
"She was hard as nails and we were scared of her but at times she was alright," the man said in a statement read by the QC.
Asked if she agreed with that assessment, the sister replied: "Not really."
"Did you get an impression that children might have been scared of you?" Mr MacAulay continued.
"No," the nun answered.
The inquiry heard how the man had recalled a time when he dropped a Bible and "got a skelping", adding the nun "had a terrible temper on her".
"Do you think you had a temper?" the lawyer asked the sister.
She replied: "Not really." She added that she could not remember carrying out an alleged assault.
SCAI chair Lady Smith later pressed the witness: "Is it possible there were occasions on which you lost your temper?"
"Maybe," the nun said.
She told the inquiry that she had not seen children punished or humiliated for wetting the bed, said she had not seen them be forced to eat food and insisted that youngsters "weren't abused" for misbehaving.
She agreed with Mr MacAulay's summation that she had not witnessed abusive practices "in any shape or form" in Aberdeen.
The woman did, however, tell the inquiry it was possible that children could have been expected to kiss the bodies of dead nuns when they went to church.
The nun said she could not remember such a thing happening but told Lady Smith it "could be possible".
However, she added that no nuns had died during her time in Aberdeen.
The inquiry later heard a statement from Sister Oliver Larkin, who was sent to Nazareth House in Aberdeen for 10 months in 1972 and worked in a hostel, or annex, on site.
In her statement, read to the inquiry by a lawyer, she said: "I don't think we ever had to discipline any of the children in the hostel ... I can say for sure the children in the hostel were never subjected to any abuse."
Regarding allegations of abuse in the main building which have been heard by the inquiry, the nun - who had no complaints against her and waived her right to anonymity - told the probe: "I would not be aware of what happened there ... I never saw anything untoward."
The statement added: "There was nothing I ever saw constituted abuse or would have needed reported."
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