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Disposables Consultancy Service

Testing


If you are, or want to be,  involved in any facet of the manufacture or sale of baby diapers, sanitary napkins, adult incontinence or similar absorbent products, please read through our pages and contact our Consultant, Philip Hardy, by phone or  e-mail. 

DCS Testing Laboratory
Diapers, Napkins & Underpads

Design and Testing for absorbent products:

The DCS Testing Laboratory is a testing facility for the design and monitoring of absorbent disposable products. We are not allied to any machine or material suppliers and so can provide a totally independent service for manufacturers and buyers.

In order to give a deeper understanding of the products and to aid in innovative design, we have developed new laboratory equipment to add to the standard testing systems prevalent in the industry.

Absorbent cores:
The key working part of an absorbent product is its absorbent core, where the fluid diffuses, is absorbed and is retained. Testing with variable pressures at increasing levels of saturation reveals the strengths and weaknesses of the core in handling the fluids. Our testing results and analyses provide a detailed understanding of the fluid mechanics within the core and the effectiveness of the absorption.
In conjunction with the absorption tests, the core is also tested for strength to ensure that it will reach its maximum absorption potential before core failure occurs.

The above chart relates to baby diapers and gives a clear visualisation of the fluid in a core related to the ability of the core to retain it. The blue surface shows the fluid as it is distributed in the core and the yellow columns show the amount of fluid that each zone of the diaper can retain under normal "baby" pressures. The area of the blue surface above the yellow columns is the amount of fluid that will wet the baby's skin each time the pressure is applied.
We work with our clients to better match the 'required' and the 'actual' profile in terms of retention, so that the raw materials are used most effectively, thus reducing the material content to the optimum level (the key to profitable manufacturing).

Please click here to view or download the recent Nonwovens Industry magazine article on diaper absorbency written by DCS Consultant Philip Hardy in May 2009

For Manufacturers    
  • Our tests and analysis will show clearly how effectively your materials are being used and where improvements can be made. (See SAP distribution and diaper cross section photos in right hand column)
  • All tests are closely related to real life usage and so can be directly related to test panel and customer feedback. Once the performance is understood, it is a simple step to achieving improvements.
  • With 2 devices that we have designed, you will be able to carry out your own design and controls in your Company laboratory. They are the Retention & Rewet Tester and the Hardy Integrity Tester. Please contact us for details and quotations.
 
For Buyers & Importers  
  • Many laboratories will carry out tests and provide wetness and leakage results and graphs. We take the process a step further and reach an understanding of why the product performs at its particular level of effectiveness. In this way the costs can be analysed and an understanding of the 'effectiveness per dollar' paid can be achieved.
 
 

New tests - new apparatus
Here at DCS we have developed an improved set of tests using new and innovative testing devices. The traditional centrifuge retention test has been replaced by a variable pressure test that gives results directly related to the full range of "real life" situations.

These new tests are described below. If you wish to have your baby diapers tested please contact us at Testing or ring us at the number shown on our Contacts page.

Baby and Adult diaper design & testing

Step by step

Step 1 - SAP Indicator analysis
Special combinations of chemicals and indicators are applied to the diapers to show the mix and spread of SAP when back illuminated. (Photo in RH column).
High SAP density (green square) and low SAP density (blue square) areas can be clearly identified.
Photos of these spreads are then combined with zoned retention tests to quantify the SAP distribution. In this way a 3 dimensional mapping of the SAP is built up for the diapers. The variation from diaper to diaper will indicate the level of control of the core formation. Click to see larger photo

Step 2 - Retention
Full and zoned retention tests indicate the fluid retention under stepped pressure. These provide a clear indication of the amount of fluid that will be released at each pressure equivalent to the baby lying down, sitting or moving. (DCS use different ranges of pressure for the different diaper sizes directly related to the baby’s weight range).
This test rig can also be used by diaper manufacturers for the monitoring of SAP quantities during production. Its advantage over the centrifuge method being that it applies a range of pressures that are similar to those encountered in usage and thus can be directly related to customer feedback. Click to see retention graph.

Step 3 - Rewet
Rewet tests are carried out in front, central and back zones, with and without the ADL layer, to show the intrinsic ability of the absorbent core to prevent fluids from resurfacing, and the effect that the ADL has on the rewet of the diaper within the critical load range. Using a zoned rewet combined with the zoned retentions of Step 2 it is possible to fully map the diffusion of the fluid through the diaper core and to understand why those rewet values are being achieved. This better understanding of internal fluid movement makes the core design a more logical process, rather than one of trial and error. Click to see rewet graph

Step 4 - Redistribution
The rewet testing device is also used to check the redistribution of the fluid caused by repeated loading of the diaper. This mimics the movements of the baby during use and indicates if the retained fluid within the core will wet the skin only once or continue to wet the baby each time that pressure is applied. A well designed diaper will allow the fluid to redistribute throughout the core when pressure is applied rather than to repeatedly come to the surface, thus reducing the incidence of diaper rash. Click to see redistribution graph

Step 5 - Pad Integrity
The diaper is tested using the Hardy Integrity Tester (HIT) apparatus. This indicates the overall ability of the diaper core to remain unbroken when subjected to impact. It can also be used to indicate the variation in strength from diaper to diaper in normal production. A diaper brand is often judged by the weakest performer in the pack, so this variation in strength can be a key factor influencing consumer satisfaction. Click to see picture of Integrity Tester

Step 6 - Wicking
The diaper is tested for wicking with saline solution. The results of this test are combined with those of the pad integrity to assist in determining the optimum density of the core. Increased strength and wicking must be balanced against the speed of absorption and the soft feel of the diaper.

Other Diaper Testing

Inspection
A full inspection of the diaper and a 3 dimensional analysis of the "fit". The fit is not just a factor of comfort or visual aspect, it affects the point of application of the urine thus affecting the spread and potential leakage of the diaper.

Test Panel
The diapers are tested on babies of different genders and different relative "shapes" to give as wide a range of performance as possible
The results are then correlated with the Inspection and Absorption tests to give a complete picture of the diaper performance. Any anomalies will be highlighted when the performance in the test panel does not match the performance predicted by the lab results.

Materials
Material testing can be carried out to determine strengths, tape adhesion, elastic tension etc, and can assist in resolving any remaining performance anomalies.

Conclusions and Design (For manufacturers)
The final conclusions reached will give a clear indication of the actions that should be taken to improve your diapers to the level that you require. We can then assist you to achieve these levels by machine tuning, material changes, machine modification or retrofitting of new units.

Please contact us if you wish to receive a proposal for testing of your product.

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Disposables Consultancy Service
Copyright © 1999  [DCS]. All rights reserved.
Revised: June 2013

 

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Backlit_Diaper

SAP distribution

Integrity

Hardy Integrity tester

 

Retention & Rewet Tester

 

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Diaper Cross Sections

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