Machine care

Modern computer-controlled drycleaning machines perform remarkably reliably, so cleaners may be surprised when a machine fault leads to problems in the load. Paying a little more attention to planned maintenance can help to avoid the problems seen here.

Most parts of the drycleaning machine are accessible for cleaning by the operator as part of the normal daily, weekly and monthly maintenance regimes. The big exception is the backplate – the hidden circular area on the rear of the stationary drum in which the cage turns. Over time this accumulates a build-up of gunge and fibrous debris and very occasionally a section of this debris and detritus will come away and fall into the liquid solvent in the drum. If this occurs towards the end of the second bath, then the entire load will become contaminated with fibrous debris and the mechanical action of the spin cycle will drive this into the textiles’ surface.

A boil-over in the still will also have dramatic results. The still contents start to foam, creating a voluminous froth that rises up the overflow and contaminates the working tank. This occurs if the still is contaminated by substances that lower the surface tension – such as excessive detergent, stain removal chemicals or certain textile finishes.

The contents of the filter must be dropped to the still once the filter pressure reaches the maximum allowable level or the stress on the filter fabric can cause a filter burst. This usually happens during the second bath, which generally features circulation over the filter so the entire load will be contaminated with deeply embedded particles.

Complaints about odours are again becoming common. These usually refer to sewer and vomit smells rather than solvent odour, which is well-controlled now thanks to improved dryness sensors. Sewer smells tend to come from microbes breeding in the water separator (at the interface between water and solvent) and acid smells, such as vomit, tend to start as the solvent breaks down in the still, which often happens beneath a residual deposit on the still wall where a hot-spot has developed.

Pastels ruined by greying

Fault: A load of pastels that was drycleaned on a normal process suffered widespread greying – far more than could have been caused by loose dye from the load. Investigation found that there had been a problem with still pressure after the previous load and the working tank’s contents had turned black.

Cause: The symptoms indicate that the still had boiled leading to “black-over”. The still contents have foamed and blown the pressure seal so that the contents have spilled into the working tank, along with the dark dissolved contamination normally found in the still.

Responsibility: The blame here probably lies with the cleaner if the foaming resulted from excessive detergent or from stain removal chemicals going to the still. The cleaner would also be to blame if the problem resulted from increasing the still temperature in an effort to speed distillation.

Rectification: The contents of the working tank should first be distilled. The load should then be re-cleaned on a two-bath program using the maximum detergent charge in both baths but the prospects for recovering the greyed items are not good.

Sewer smells spoil the work

Fault: Dank sewer smells started to affect heavy woollen coats, then the problem spread to all cleaned items.

Cause: Sewer smells come from amines, fatty acids, nitriles and other organic compounds produced by the breakdown of human and animal detritus. They can be produced in the still, in the water separator (at the solvent-water interface) or from the unknown, invisible debris that builds-up on the backplate.

Responsibility: The drycleaner is responsible as these smells result from inadequate cleaning regimes over the past 12 months.

Rectification: The only way to remove sewer smells from the machine is to remove or kill the breeding micro-organisms that are usually the main source. All the solvent must be distilled. The still must be cleaned and the water separator, the distilled water tank (and possibly the working tank) must be cleaned and sterilised with a weak (2%) solution of sodium hypochlorite. Follow strict health and safety precautions. It is wise to treat all pumps and pipework the same way. Some highly resistant bacteria will return again and again, so a single clean is rarely sufficient.

Shop smells of vomit

Fault: Drycleaning sales had been gradually declining as customers began to complain of vomit smells on clothes after cleaning.

Cause: Vomit odour is caused by butyric acid, a fatty acid produced by the human stomach and by a variety of other enzymatic and microbial reactions.

It can develop from the breakdown of animal slobber on hairs that stick to the backplate after cleaning horse blankets. It can also result from the breakdown of some dairy products such as parmesan cheese.

Alternatively this smell could be a by-product of the entire machine becoming acidic following the chemical breakdown of solvent and contaminants in the still. This usually results from a combination of certain food soiling and machine hot spots .

Responsibility: The cleaner is responsible for keeping the drycleaning machine as near to neutral as possible, by controlling distillation conditions carefully and by thorough and regular still cleaning. Any cleaner that is losing custom as a result of complaints about vomit odours should also take responsibility for more frequent and more effective cleaning of the backplate.

Rectification: Thoroughly clean the still, the water separator and the backplate. Then use pH papers to measure the separator water’s acidity after the next load. If it is outside the range pH6 – pH7.5 then a buffering additive should be dosed into the still to correct this immediately. It may be necessary to lower the distillation thermostat temperature by 2 – 3C if the pH continues to be outside the target range.

Dark fibres mark the load

Fault: When the cleaner opened the cage door he saw that the whole load was covered in dark fibres. The problem was too extensive to be caused by contamination from the load.

Cause: These symptoms point to a backplate drop in which part the normal build-up of debris has fallen into the solvent and so contaminated the load.

Responsibility: The cleaner is the only person who can ensure the backplate is as clean as possible.

Rectification: First distill the working tank’s contents. Then re-clean the load with distilled solvent, using the maximum detergent charge in both baths to try to trap as many of the dark fibres as possible. If this improves the result, repeat the process. In future, clean the backplate monthly on a maintenance cycle. This involves filling the empty cage with a high solvent dip then rotating the cage as in a normal cleaning program to try to clear the backplate as much as possible with lots of sloshing action.

Don’t neglect filter checks

Fault: A dark load cleaned well but every piece was marked with coloured particles and fibres.

Cause: The filter pressure has been allowed to exceed the maximum allowable so the supporting fabric has burst. Much of the particulate dirt, which the filter has removed from previous loads, has contaminated the circulating solvent and eventually affected the cleaned items.

Responsibility: Regularly checking the filter pressure and dropping the filter contents to the still is one of the most important maintenance tasks. This cleaner has almost certainly neglected to do this and is therefore to blame.

Rectification: Distill the working tanks as these could have been affected. Then re-clean the work on a two-bath program using the distilled solvent dosed with the maximum detergent charge for both baths. The prospects for full recovery are poor.