Become richer: work for nothing. That's one of the slogans to attract volunteers. You have time on your hands, you have a social conscience, so why not give something back to society? The simple way would seem to be to volunteer; to trade what you have - time - to make someone else's life better.

Except it's not always that easy. Glasgow-based film-maker Kate E Deeming spends most of the year working on film and theatre projects in exotic locations. She was keen to spend a six-week break in December and January working for a local charity. She had spent the previous Christmas helping in a Gorbals soup kitchen but was keen get involved with a longer project. However, despite starting her search in October, she was unable to organise any volunteering.

Deeming, 33, believes charities are not set up to accept volunteers at short notice or for short periods and are, therefore, missing out on a large pool of people.

Her first idea was to call the Volunteer Centre in Glasgow, which puts potential volunteers in touch with organisations that need help. "I wasn't able to get an appointment with the relevant person until almost a month later. I said I was willing to do almost anything: stuff envelopes, serve soup," she recalls. "I am young and physically able and have lots of experience and am happy to work with special needs, elderly, homeless. I was like: I'm a here, I'm a resource, please use me.

"The people at the centre were lovely and they had wonderful resources but it quickly became apparent that volunteer organisations are really only set up to receive volunteers over a longer period; you need to make at least a six-month commitment. Because of the work I do, I can be away up to once a month so I can't do that."

After attending the interview at the Volunteer Centre, she was given several leads for vacancies and phoned the individual charities repeatedly. She never received a call back. She also called several nursing homes, offering to come in and keep residents company, adding: "They all wanted me to come in but it was not possible because of the disclosure procedure, which takes weeks."

After two months of searching, Deeming gave up. Did she simply have a run of bad luck or are charities missing out on potential volunteers because of red tape and protracted application procedures?

The bare statistics demonstrate that volunteers are vital to these organisations. Scotland has 50,000 voluntary organisations which employ 109,000 paid workers but rely on eight times that number of volunteers - around 850,000.

The Samaritans are one of the best known organisations and recruit constantly. But because of the skilled nature of the work, the application process is lengthy. Cassie Gibson, who chairs the Ayrshire branch, explains that after filling out an application, individuals receive an information pack, then a Disclosure Scotland check is carried out before they are invited to a selection day. For those who are successful, there is an eight-module training course and, finally, a six-week mentoring stage. "We do ask for a commitment in hours," says Gibson. "We get a lot of people who make an initial inquiry and realise what the commitment will be; it's not for everybody."

While the application is protracted owing to the training requirement, Gibson estimates the disclosure check can add six weeks to the process. It's the same kind of story at Glasgow City Mission, which is more geared to accepting help over a longer period. Office manager Susan Robertson explains: "We tend to get most of our volunteers by word of mouth. There is an application process, almost like a job application. We can't really have people just turning up because of disclosure. It also means that everything takes a wee bit longer, up to eight weeks. We make it clear in the application that we are looking for a long-term commitment."

David Maxwell, spokesman for Glasgow's Volunteer Centre, believes the process is becoming quicker. "In the past four years since the disclosure legislation was implemented, it may have taken weeks, even months, but since last year most enhanced disclosure certificates are taking four weeks at the most."

He also points out that disclosure checks only affect certain voluntary positions: those involving work with children or vulnerable adults. "Disclosure is just part of the process. References need to be taken up and there may be induction training before people can start. However, there are opportunities that don't require any major selection procedures, such as gardening or conservation work, and helping out in shops or at fundraising events."

The Volunteer Centre deals with all aspects of volunteering and has around 500 opportunities on its database. Maxwell says: "While most of these are looking for an ongoing commitment, we will do what we can to find roles for people who are only available in the short term. There are plenty of opportunities which offer tasters, where you can go along and try it out. We also help large companies with one-off projects that people can get involved with."

However, if the average time to get an appointment is almost a month, it would appear to exclude those who can only commit short-term. Maxwell confirms that at busy periods it can take weeks to get an appointment but says the majority of volunteers now use the online database. "In the past financial year to March 2006, between 3000 and 4000 people arranged volunteering through our online service, which allows volunteers to contact charities directly. A further 2000 people did so after coming in for an appointment or by phoning the centre."

Once in contact with a charity, it can be a relatively fast turnaround. Oxfam has a strong presence on the high street and around 2000 volunteers work in its shops across Scotland. John Connelly, manager at the Byres Road bookshop in Glasgow, says: "In some ways it is similar to applying for a job in that you need to fill out an application and supply references. The fastest time from initial application to being able to volunteer is a week, providing that references are received and that the shop has an immediate requirement for help."

Once individuals have volunteered for Oxfam, the shop will keep the original application for some time so volunteers need not re-apply each time they want to help out.

Marjory Wood, spokeswoman for the British Heart Foundation, admits that the charity does not have volunteering opportunities for people who have a month to six weeks to offer. "If an individual has a little spare time on a regular basis then BHF Scotland would be delighted to hear from them. It may be that they would like to help out with our events, for example by carrying out some marketing or by marshalling a walk or bike ride."

So while the majority of charities may not be able to accommodate short bursts of volunteering on a one-off basis, repeated short bursts once a person has signed up with a particular organisation might just be the key.