It might be that next of kin have moved overseas or died themselves.
"It's important to us that we do what's right and get back in touch with these families and if we can't by the end of the year we will have a committal service at the crematorium and the ashes interred after a ceremony."
He said it was not uncommon for funeral homes to hold on to ashes. Sometimes they keep them until other family members die so ashes can be scattered together, or until family members return from overseas.
Richard Bennison, funeral director at Grays, said he had 142 sets of ashes, the oldest dating back to 1963.
He is still operating in Rotorua but all his prep work is carried out in Tauranga.
"We'll hold on to these ashes until they are claimed," he said. "I'm pretty sensitive about it."
Leftover ashes are not a problem for Mountain View funeral home.
Attitudes towards death were different these days, said managing director Erin MacDonald.
"There's no right time for someone to pick up ashes as every family is different," Mrs MacDonald said.
"We make ourselves aware of how they are coping. Our baby boomers are the ones now caring for their parents and they're a different generation.
"They want to do things by mum and dad and there's a different attitude towards death as it would have been 20 to 40 years ago. It's a lot more accepting and easier as a funeral director to talk to families about collection."
Collingwood funeral home is one of the newer funeral homes in the city. "I've heard of some funeral homes having ashes dating back 50 or 60 years and it can be hard contacting next of kin, but being relatively new in Rotorua we don't have that problem," said owner Todd Gower.
"I know of a home in Auckland that was in a similar situation and any unclaimed ashes would be buried on a certain date in a mass burial. It's not ideal but something needs to be done.
"We're lucky that we don't have that issue at this stage, we've only been here 12 months and these days people aren't so afraid, it's not such a taboo subject."
He said most of the families they worked with collected ashes within a month of a funeral.
A Whitehaven Funeral Home spokeswoman said they did not have any outstanding ashes in their care.
-If you think the ashes at Osbornes may belong to a family member, call Mr Fullard on 07 348 3600.