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- 42 Main Street ● PO Box 778 Phone: (845) 856-2995
- Sparrow Bush, NY 12780 Fax: (845) 856-4665
- E-mail: George@sciservsd.com
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Report of Effect of Age of Blood Stains on Ease of Removal About a year ago a client brought to our attention a serious problem with our Blood Stained Cloth. They found that stain removal changed drastically over a period of several months. Since we had never used a single lot of Blood Stain in a study that lasted more then a few weeks, we had never encountered this problem. To check these reports, we laundered a number of different lots of Blood Stained Cloths that were various ages; we found that stain removal varied by large amounts but with no obvious relationship to age or any other factor for that matter. We then set up a long term study to monitor Blood Stain removal vs. time; large lots of Blood Stain on three fabrics were made and laundered over nine months. The results are shown in Chart 1. Unfortunately we ran out of Blood Stain before the stained cotton had set completely. There is a long "incubation" period and then stain removal drops rapidly. If a test had been planned during the period of rapid stain setting, the comparisons would not be independent of time. In an in-house test we found that the comparison of several detergents for blood stain removal could be modeled mathematically if Blood Stain Age was treated as an independent variable, but we were fortunate that we were on a part of the curve where stain removal was declining linearly with age.
To stabilize the amount of stain removal we tried aging the Blood Stain at an elevated temperature. Data plotted in Chart 2 shows the effects of such treatment on the Blood Stain on the three (3) common fabrics: cotton, cotton-polyester (durable press) and polyester. Note that heat treatment made the percent stain removal lower indicating that the stain has been set somewhat. However, there is still a decrease in stain removal over the four week period. For much of 1998, we used this technique.
On the advice of a client we tried another approach. John Barrett told us that high humidity will accelerate the setting of Blood Stain. We experimented and found a set of conditions of time, moisture content and temperature that set the Blood Stain and gave the results shown in Chart 3.
Although the amount of stain removal is low, the Blood Stained Fabrics are reproducibly sensitive to household detergent and laundry conditions. So, our current standard procedure is to age our Blood Stained Cloths damp and warm. You will see much lower stain removal, but the results with a single lot should be reasonably stable over time. If you want to see a more complete Blood Stain removal, we can provide you with a special lot made to order. You should be cautioned, however, that the age of the stain and degree of setting may then be a large variable in your experiment and thus, should be taken into account. |
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