Concerns about hygiene on hospital wards – in particular the fight to stop the spread of infection such as MRSA – have been the subject of tremendous media coverage. As a result, more healthcare providers are now having to assess all services, including laundering of textiles, to determine hygiene standards.

Almost every medical procedure involves the use of textiles in some form and these textiles are routinely laundered (unless the healthcare operator has taken the more expensive route of 100% disposable).

Every laundry manager needs to be certain can they be that the laundry is achieving adequate levels of disinfection.

The contact dipslide (like those produced by CASP Products) is a simple and cost effective method that is available to any launderer.

While it not deadly accurate and will not identify the specific numbers of any specific micro-organism, it is an excellent management tool that gives potential warning of problems.

The dipslides are plastic “tongues” which are coated in agar, a medium that encourages microbiological growth, and, after contact with a textile or immersion in water, replaced in holder and incubated for up to four days.

There are two main types that are of great value to the launderer.

The MacConkey dipslide is designed to assess the total viable count (TVC) of micro-organisms on one side of the contact surface and on the other assess the level of coliforms, (normally present in faeces/excreta and a principle cause of gastro-intestinal infections).

The other dipslide is the Malt agar which also measures for TVC on one face but also looks for moulds and fungi on the other face.

It is really worth while using these to verify just how effective the laundry’s wash processes are at achieving implied disinfection by gently sandwiching a MacConkey dipslide in between layers of damp work as it exits the press (for tunnel washers) or the hydro.

Ideally the dipslide should be incubated at around 35C (within 1 or 2C either way) for three to four days – but often keeping them in a warm office or cupboard is sufficient.

It is then possible to assess the level of micro-organic growth left on the fabric after washing.

Ideally the dipslide should remain perfectly clear. If there is any growth, it will normally show as bright red marks on the dipslide contact surface.

The extent of the growth can be calibrated against the example illustrations which are supplied with the dipslides.

As a launderers’ tool, a dipslide assessment can be graded as follows:

up to 102 equates to “amber” and potential danger

between 102 – 104 is equal to a “flashing red light” and there is a real risk of danger

more than 104 – there is a serious problem that needs urgent investigation.

It is good practice to use these dipslides at least once a month (and ideally every week) in each of the following main areas in the laundry:

water supply to the washroom

damp washed articles

and finished, dry articles ready for despatch.

They can be used almost anywhere, for example, work surfaces, employee hands, conveyors, packing equipment, transport trolleys.

Indeed, they will provide a good general guide to the levels of hygiene almost anywhere in the laundry.



Saying goodbye to the halo effect

Fault: The blue and white pinstripe shirt pictured here appeared to have been well washed and laundered – but there was a problem with a blue aura or halo effect, which was particularly noticeable on the collar and cuffs along the seams.
Standard testing for colourfastness and residual bleaching agents failed to identify the cause.
Close examination of the shirt confirmed that although the blue halo effect was more noticeable on the collar and cuffs, it was also affecting other areas of the shirt (albeit to a lesser extent) on virtually every seam.
The blue marks totally disappeared when examined under ultraviolet light. This blue was excessive OBA, which was then re-confirmed when viewed under ultraviolet light using OBA filters.
Microscopic examination identified very fine particles of powder concentrated around the fibres closest to the multiple seams.
Cause: The detergent used to process this shirt has a high level of insoluble filler, which was used to carry the OBA in the detergent formulation. Due to the multiple thickness of material, especially on collars, cuffs and seams, the insoluble filler, with the OBA, was effectively “filtered” by the multiple layers of fabric to cause the result seen in the photograph.
Solution: A hot wash with just alkali was adequate to remove the insoluble filler/OBA build-up – combined with a change of detergent supplier.



Heat sensitive agent turns towel yellow

Fault: Towels sent in to a laundry by a new customer were turning yellow.
Normally when a white article turns yellow, experience suggests it is the result of one of three possible causes – poor rinsing (alkali “galling” or residual sodium hypochlorite); scorching from over-drying; or iron (Fe) build up on the fabric. Initial tests on the towel sent for analysis showed a higher than normal iron content. But this did not solve the problem as the launderer said that no other items in the plant were turning yellow and that only towels from this particular customer were affected.
Further tests on both new unwashed and washed towels confirmed a level 5 iron (Fe) contamination but the washed towel was pH 4.5 – somewhat acidic and when warmed had a slightly “vinegar” residual odour – against the new towel’s pH 8.
Treatment of the yellowed towel with hydrofluoric acid failed to remove any of the iron (Fe). It was not until the two towel samples were viewed together under ultra-violet light that a slight variation in the brightness between the sample towels could be detected.
Cause: Closer examination of the towels under strong direct UV light showed that the washed towel had a slightly lower OBA (optical brightening agent) level than the new towel, which shouldn’t happen.
The new unwashed towel was then subjected to contact with a standard domestic hand iron at 110C (v). When viewed under UV light, there was the outline form of the hand iron and a slightly cream tint. When the temperature of the hand iron was increased, so too was the creamy yellow discolouration, which was only affecting the tops of the loops forming the towel.
The basic weave of the towel, which had no direct contact with the heat from the sole plate of hand iron, was relatively unaffected. The yellow discolouration was due to the manufacturer using a heat-sensitive OBA during manufacture, which neither the supplier nor the launderer could have known about.
Solution: Once the towels are being used, the only solution is to remove the damaged OBA by using an OBA quencher, and then rely upon the OBA in the selected detergent formulation to gradually replace the original OBA.