Art, Science, and Cleaning Liquid

I've started doing some experimentation with discharge dyeing. That's "experimentation" as in "lab experiments".

I'm playing with discharge dyeing because I'm preparing to teach it to a bunch of middle school kids, and I haven't done discharge dyeing before. These kids are currently learning about the process of scientific inquiry and writing lab experiment reports. Their curriculum integrates that scientific method into several of their classes, and I'm going to integrate it into an art class too. I'm hoping they'll have fun doing the dyeing, so I won't make them write an actual report! In the meantime, it's time to brush up on doing lab reports myself (it's been quite a while!), and they can read mine. Here goes...

Lab Report

Title: Discharge Dyeing Using Liquid Cleanser with Bleach

Table of Contents

Introduction………………………….………………………………………………………page 1
Methods……………………..……………………………………………………………....page 2
Materials……………………..…………….………………………………………..page 3
Variables……………………..…………….………………………………………..page 4
Procedures……………………..…………….………………..……………………..page 5
Data & Observations……………………..…………….………………………………..…..page 6
Analysis……………………..…………….……………………………………..…………..page 7
Conclusion……………………..…………….………………………………..……………..page 8
Works Cited……………………..…………….……………………………………………..page 9

Introduction

Background & Purpose

Discharge dyeing is the process of stripping out color that is already in the fabric (bleaching it) for artistic effect. Sometimes discharge dyeing happens by accident, such as when a cleanser with bleach in it was spilled on my favorite electric blue bathmat. It took me a while to realize how it got those bright pink spots on it, since bleaching doesn't always make the fabric white--often other colors result, depending on the dyes that were used. Here is a good example of accidental discharge dyeing.

There are many ways to do discharge dyeing. The methods and chemicals used depend on what type of fabric you want to alter. For example, common chlorine bleach works well on cotton, but it will deteriorate wool or silk fibers. For silk or wool, sodium hydrosulfite or thiourea dioxide can be used instead.

In addition, you can use different methods to achieve different bleaching or lightening effects. For example, to lighten an entire piece of cotton fabric, you might dip it in a dilute solution of chlorine bleach and water. However, to create stenciled effects, it might be helpful to have a thicker bleaching compound. The web page "DISCHARGE DYEING WITH COMET GEL" suggests using Comet Liquid Gel or Soft Scrub with Bleach for discharge dyeing with stencils.

Since I am planning to do stenciling with discharge dyeing, I decided to investigate how well the Soft Scrub with Bleach worked. The store had that and Safeway Liquid Cleanser with Bleach (on sale), so I got both.

My research question asks whether there is a difference between using different brands of liquid cleanser with bleach (Soft Scrub and Safeway) and how it is affected by time on the fabric. I selected my research question because I was curious as to which bleaching compound would work better and what time period was needed.

Hypothesis & Prediction

The hypothesis is that there is a slight difference in the performance of the two cleaning fluids for discharge dyeing, because store-brand products usually do not completely duplicate the national-brand products they are emulating (occasionally they are better). Typically the store-brand products are cheaper and may be made from cheaper materials. Because this is a non-standard use for the cleaning fluids, either may be the better performer for this purpose.

I predict that the outcome of my experiment will be that both products work for my purpose of discharge dyeing because both contain bleach. I predict that there may be a slight variation in the shades achieved with the two products. The null hypothesis is that there is no difference in the shades achieved with the two products.

Methods

Materials

• Soft Scrub with Bleach cleaning liquid (24 oz.)
  
• Safeway Cleaning Liquid with Bleach (24 oz)
  
• Denim fabric scraps (denim scraps from my jeans circle quilt) in various shades
  
• Two small applicator squeeze bottles
• Permanent marker (blue or black) that will show up on the darkest and lightest denim scraps
  
• Warm water for washing off the liquid cleansers (running water in a sink)
  
• Old toothbrush or scrub brush for scrubbing liquid cleanser off of denim scraps as needed
• Goggles and plastic gloves
  

Variables

• variable – something that can vary (or change) each time an experiment is done
• controlled variables – the variables that you "control" or keep the same during all of your experiment. Controlling is also called standardizing.
• manipulated variable – the variable that you are intentionally changing so that you can make comparisons between different situations, objects, or conditions. Also called the independent variable and is graphed on the x-axis.

The manipulated variables in my experiment were the brand of liquid cleanser, the time the cleanser spent on the fabric, and the shade of denim fabric.

• responding variable – the variable that is changing due to differences in the manipulated variable. It is the variable you are measuring and recording as the outcome of the experiment. Also called the dependent variable and is graphed on the y-axis.

• Since my experiment samples made up a 2-dimensional matrix with denim shade on one axis and time on the other axis, I essentially had multiple experiments. I controlled for denim shade against cleanser brand in one experiment, and I controlled for time against cleanser brand in the other experiment.
  

• My manipulated variables were the brand of liquid cleanser on the sample, the time it was allowed to sit on the sample before being washed off, and the original shade of the denim.

• My responding variable(results) was the whiteness/brightness (visibility) of the discharge-dyed area (the bleached mark on the fabric).

Procedures

1. Put on gloves and goggles.
   
2. Put some Soft Scrub cleanser into squeeze bottle (about half full) and mark the bottle as "A" with the permanent marker.
3. Put some Safeway cleanser into squeeze bottle (about half full) and mark the bottle as "B" with the permanent marker.
   
4. Prepare samples of the clean denim fabric scraps. Cut samples to sizes at least 2 inches by 6 inches. Cut four samples of each fabric shade (that is, cut 4 samples from each pair of jeans so you have multiple matching samples for each shade of denim).
5. Use the permanent marker to label each sample with a time (in minutes): 10, 15, 25, and 60 or Overnight (Note: for some shades I did not have enough for all four samples, so I made fewer samples).
6. Lay out all the samples on a table. You will have a matrix of samples with time in one direction and denim shade in the other direction.
   
7. Using the "A" (Soft Scrub) squeeze bottle, write an "A" on one end of each sample.
8. Using the "B" (Safeway) squeeze bottle, write a "B" on the other end of each sample.
9. Start the timer.
10. At the end of each interval (10, 15, 25, and 60 minutes or Overnight), wash out the samples for that time period under running warm water. Use the toothbrush or scrub brush if needed to get the cleanser grit out of the sample.
11. Set the samples out to dry.
12. Lay out all the dry samples and look at the quality of the discharge-dyed letters (A, B) on the samples. Are they hard or easy to see? Are the edges of the letters sharp or blurry? What colors are the letters (white, blue, pale blue, yellow, and so on)?
13. Write down observations for each sample based on the key chart below.
    

Data & Observations

Without very sophisticated equipment, determining the amount of bleaching is fairly subjective, so I have made up a qualitative scale (key table) by which the bleaching can be judged.

Here are the results for the various samples, according to the key given above. Click on the following table to enlarge it:


Here is a bar graph of the results, where each group of bars represents all shades bleached for a specific period of time. Click on the graph to enlarge it:


Here are photos of the bleached, rinsed, and dried samples, arranged by denim shade (dark, medium, and stonewashed). "A" is bleaching from the Soft Scrub cleanser. A "B" should appear on the right-hand side of each sample, but it appears only faintly in two of the samples ("dark 60 minutes" and medium overnight, "BO").

Dark denim at 10, 15, 25, and 60 minutes:


Medium denim at 10, 15, and 25 minutes and overnight:

Stonewashed denim at 10 and 25 minutes (15 minutes not shown):

As listed in the results table, the "B" (Safeway brand cleanser) is not visible at all in most of the samples, and is only very faint in the two where it appears at all.

I observed that the Soft Scrub cleanser turned yellowish or orange around the edges as it bleached the dyes below it, probably from reacting with the dyes. It also became just a little less shiny than it was when it was applied. The Safeway brand cleanser remained bright white and shiny just as it was when it was applied. For the overnight samples, both cleansers became slightly dried out and less shiny.

Analysis

In this experiment, I compared the bleaching effects of two different brands of liquid cleansers with bleach. I compared them across various soaking times. I also compared them across three different shades of denim.

I used an advanced set of equipment, my eyes, to collect the data (the responding variable), and quantified my results using the qualitative scale above.

The data does not support either the hypothesis or the null hypothesis. The null hypothesis was that the results would be the same for both brands of liquid cleanser, and that was clearly not the case, since the performance was very different between the two brands (and the Safeway brand barely bleached the denim at all). The hypothesis predicted a slight difference in performance between the two brands. Because the Safeway brand barely bleached the denim at all, while the Soft Scrub worked as expected (bleached the denim visibly in 10 minutes, and more with increasing time), I maintain that there is a significant, not slight, difference in bleaching performance between the two brands.

Conclusion

My personal prediction about the outcome of the experiment was surprisingly incorrect. I had expected the Safeway brand cleanser to produce results only slightly different from the results of the Soft Scrub cleanser, since both purported to contain bleach, which is the ingredient of interest. Instead, the Safeway cleanser had almost completely failed to bleach the denim, while the Soft Scrub cleanser had bleached the denim as expected. As expected, the Soft Scrub had produced more bleaching effect (whiteness) over greater time periods. For what little bleaching it did produce, the Safeway brand cleanser had also produced more bleaching for longer times, as expected.

Keeping the bleaching times precise was a challenge because I was participating in other activities at the same time and did not have a timer handy (just a wall clock). However, given the imprecise nature of quantifying the results, a minute or two, plus or minus, does not seem to affect the precision of the results. Also, I had originally intended to do a set of samples at five minutes. This became a ten-minute sample set because I missed the five-minute rinse time.

If I were to repeat the experiment again in order to do it more carefully or accurately, I would use one or more kitchen timers so I could time my experiment more carefully. I would also prepare somewhat smaller and more uniformly-shaped samples, and more of them so I could get a more complete data set.

For a future experiment, I would try using the Soft Scrub cleanser with additional types of fabrics beyond denim, such as with wools, synthetics, and so on, and with different colors and dyes, such as over-dyed jeans, printed synthetic fabrics, tie-dyed t-shirts, and so on.

Works Cited

WEBSITE

"DISCHARGE DYEING WITH COMET GEL" Purrfection Artistic Wearables. Dana Marie Design Co. 5 October 2008.
http://www.purrfection.com/projects/dischargedye.htm

"DISCHARGE DYEING". 5 October 2008
http://tpa4244-01.sp00.fsu.edu/discharge.htm

Vintage Threads(blog). "Discharge Dyeing Tutorial". 5 May 2008, accessed 5 October 2008.
http://vintagethreads.blogspot.com/2008/05/discharge-dyeing-tutorial.html

Hewitt, Paula. The Beauty of Life (blog). "Discharge dyeing: husbands and bleach don’t mix". 20 January 2008, accessed 5 October 2008.
http://paulahewitt.wordpress.com/2008/01/20/discharge-dyeing-husbands-and-bleach-don%E2%80%99t-mix/

"Discharge Dyeing FAQ". 5 October 2008.
http://www.quilt.com/FAQS/DischargeDyeingFAQ.html

Grace, Twila. Twila's Threads (blog). "Dye Discharge Results". 23 September 2007, accessed 5 October 2008.
http://twilagrace.blogspot.com/2007/09/dye-discharge-results.html