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The Skinny on Moisturizers: Which Works Best to Keep Skin Moist?

Difficulty
Time Required Long (2-4 weeks)
Prerequisites None
Material Availability You will need to purchase petri dishes online. See the Materials and Equipment list for details.
Cost Average ($50 - $100)
Safety Adult supervision is recommended for using the stove.

Abstract

Does your skin get dry? Or do you know someone with dry skin? Dry skin can be a real medical problem for some people. You may have seen many kinds of lotions, creams, and ointments advertised as restorative for dry skin, especially dry hands. But how well do they work? And which ingredients are most important in making them work? In this science project, you will create a model of human skin using JELL-O® and test how well skin moisturizing products with different ingredients keep the model skin moist.

Objective

Investigate how well different ingredients in skin moisturizing products (i.e., lotions, creams, and ointments) work at keeping a model of human skin moist.

Credits

Teisha Rowland, Ph.D., Science Buddies

This science project idea is based on the following California state science fair project:

  • Wilcox, K. (2006). Fishing for relief: A remedy for ichthyosis. California State Science Fair.
  • JELL-O is a registered trademark of Kraft Foods.
  • KidsHealth is a registered trademark of the Nemours Foundation.
  • Eucerin and Aquaphor are registered trademarks of Beiersdorf AG.
  • Aveeno is a registered trademark of Johnson & Johnson.
  • Burt's Bees is a registered trademark of the Clorox Company.
  • Vaseline and Suave are registered trademarks of Unilever.

Cite This Page

MLA Style

Science Buddies Staff. "The Skinny on Moisturizers: Which Works Best to Keep Skin Moist?" Science Buddies. Science Buddies, 7 June 2013. Web. 23 July 2014 <http://www.sciencebuddies.org/science-fair-projects/project_ideas/BioMed_p015.shtml?from=Blog>

APA Style

Science Buddies Staff. (2013, June 7). The Skinny on Moisturizers: Which Works Best to Keep Skin Moist?. Retrieved July 23, 2014 from http://www.sciencebuddies.org/science-fair-projects/project_ideas/BioMed_p015.shtml?from=Blog

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Last edit date: 2013-06-07

Introduction

By weight, skin is the largest organ in the human body and serves many important functions. Your skin protects you from disease and infections (such as those caused by bacteria and viruses), cold and hot temperatures, and from the sun. Clearly it is important that your skin be healthy and intact so that you as a whole can be healthy.

A common problem people have with their skin is dryness. Dry skin looks and feels rough instead of smooth, may have small cracks and/or peel off in flakes, and, in some serious cases, may have redness, bleed from deep cracks in the skin, and/or itch intensely. If a person has dry skin and the symptoms are severe enough, such as open sores or large affected areas, medical attention might be needed. Dry skin can be caused or worsened by a number of factors, including living in a dry climate (or a cold, arid winter), excessive bathing (such as repeatedly washing hands), using harsh soaps, or scrubbing the skin too much. Sometimes having dry skin is a symptom of an underlying medical condition, such as eczema, psoriasis, dermatitis, xeroderma, and ichthyosis.

Often doctors recommend treating dry skin with moisturizers (which should help keep the skin moist), such as ointments, creams (often spelled "crèmes" by their manufacturers), and lotions. (If the case is severe, other medicines may also be prescribed.) Figure 1 below shows many different types of moisturizers sold to treat dry skin.

Medical Biotechnology science project Image of different lotions, cremes, and ointments
Figure 1. Several different types of moisturizers are sold to treat dry skin.

Dry skin may be lacking water or important oils that help keep the skin moist. Moisturizers usually have many ingredients that should work to add, or keep, oils and water in the skin. The three main groups of moisturizer ingredients are:

  • Occlusive agents. Basically, they create a physical, protective film on the skin that keeps water in. Some examples include petroleum jelly (also called petrolatum), oils (like mineral oil or coconut oil), waxes (like beeswax), and others.
  • Emollients. These work by filling in tiny cracks in the skin to smooth out flakes and roughness. (The term "emollient" is also used to refer to moisturizing products in general.) Many occlusive agents are also emollients, such as petroleum jelly, mineral oil, some other oils, and waxes.
  • Humectants. These bring water to the skin's surface from sources nearby, which often means deeper layers in the skin. Specifically, when you have dry skin, the top layer of the skin, called the epidermis, may be dry, but the layer of skin below it (called the dermis) may have water, and so humectants draw the water up from the dermis to the drier epidermis. (Humectants can also use water from the environment, but only if it is humid enough.) Some examples of humectants include glycerin (a thick liquid made from fats and oils), alpha hydroxyl acids, urea, and honey.

In this medical biotechnology science project, you will investigate how well different ingredients in skin moisturizers work at keeping a model of human skin moist. While many different types of occlusive agents, emollients, humectants, and other ingredients can make up a given moisturizer, in this science project only a few ingredients will be investigated, so it will be easier to draw conclusions about them. Specifically, you will investigate petroleum jelly, mineral oil, glycerin, and triethanolamine, an ingredient sometimes added to skin moisturizers that is suspected of actually causing skin dryness. Triethanolamine is added to make a moisturizer less acidic, or, in other words, increase its pH. (This is a complex topic, and understanding it is not essential to doing this science project, but if you want to learn more, check out the Science Buddies resource Acids, Bases, & the pH Scale.)

The skin model you will use will be JELL-O® in petri dishes. JELL-O is a gelatin dessert mostly made from water and gelatin, which is a substance derived from collagen. Collagen is a group of fibrous proteins found in many tissues in humans and other animals, where it helps connect and support tissues. It is commonly found in the skin and is particularly important in the dermis layer. While this gelatin dessert will be used as a model for human skin in this science project, it is clearly different from human skin. As with any model, keep in mind how your model is different from the real thing (i.e., human skin). Check out the KidsHealth® resource in the Bibliography below to learn more about human skin.

To investigate mineral oil, glycerin, petroleum jelly, and triethanolamine in moisturizers, you will need to examine closely the lists of ingredients on different products. Look for moisturizers marketed for "dry skin" specifically, and then look not only at the list of ingredients in the product, but also the order in which they are listed. (Ingredients are listed by most abundant to least abundant. In other words, if mineral oil is listed first, the product contains more mineral oil than any other ingredient. If it is listed second, it is the second most abundant ingredient, but the product still probably contains a lot of mineral oil.) Figure 2 below shows ingredient lists from three different products to give you an idea of what you will examine.

Medical Biotechnology science project Image of the ingredients in different lotions and cremes
Figure 2. This image shows ingredient lists from three different lotions or creams (none is from an ointment). The top shows a product that lists glycerin as its second ingredient (after water). The bottom left is a product that lists glycerin second, but also includes triethanolamine (near the end of the list). The product on the bottom right lists glycerin fourth (as "vegetable glycerin").

To investigate how mineral oil in a moisturizer affects the human skin model, you will need a moisturizer product that lists mineral oil as the first or second ingredient. This may likely be an ointment, because ointments are mostly oil. To investigate glycerin, look for a product that lists glycerin as the second ingredient (after water) and a product listing glycerin as the fourth or lower ingredient so that you can see the effect different amounts of glycerin have. (These products will be either lotions or creams; lotions usually contain more water than oil, making them thinner than creams, or cremes, which contain about equal amounts of water and oil.) To investigate petroleum jelly, use a product that is 100% petroleum jelly (commonly sold by Vaseline®). To investigate triethanolamine, find a product that lists it anywhere in the ingredients. For additional details, see the Materials and Equipment section in the Materials tab.

Terms and Concepts

  • Skin
  • Dry skin
  • Moisturizers
  • Occlusive agents
  • Petroleum jelly
  • Mineral oil
  • Emollients
  • Humectants
  • Epidermis
  • Dermis
  • Glycerin
  • Triethanolamine
  • Gelatin
  • Collagen
  • Ointments
  • Lotions
  • Creams (or cremes)

Questions

  • Why can it be harmful to have dry skin?
  • Why do manufacturers include mineral oil, glycerin, petroleum, and triethanolamine in skin moisturizers?
  • How well do you think each ingredient (mineral oil, glycerin, petroleum jelly, and triethanolamine) will enable the human skin model to stay moist?
  • Which ingredient(s) — mineral oil, glycerin, or petroleum jelly — do you think will keep the human skin model moist the longest? Why?

Bibliography

For help creating graphs, try this website:

Materials and Equipment

  • Permanent marker
  • Different skin moisturizers to test (at least 5). You will need 3 fluid oz. of each one. Look for products marketed specifically for "dry skin." See Figure 2 in the Introduction in the Background tab for examples of what to look for. Pick at least three of the following five types of skin moisturizers to test (examples of each type are given):
    • A moisturizer that lists glycerin as the second ingredient, after water. Make sure it does not also contain triethanolamine.
      • Examples: Eucerin®'s intensive repair extra-enriched hand cream, or Aveeno®'s active naturals skin relief hand cream intense moisture, which is available online at Amazon.com.
    • A moisturizer that lists glycerin as its fourth or lower ingredient (and does not contain mineral oil or petrolatum [petroleum jelly] among the first three ingredients, or triethanolamine anywhere in the list). This may be a cream that is mostly oil and/or butter-based.
      • Example: Burt's Bees®'s honey and grapeseed oil hand crème, available online at Amazon.com.
    • A moisturizer that lists mineral oil as the first or second ingredient. This may be an ointment. If mineral oil is listed as the first inactive ingredient, it can be used if only one active ingredient is listed and it is less than 50%. Make sure it does not also contain triethanolamine.
      • Example: Aquaphor®'s healing ointment, advanced therapy (or advanced healing), available online at Amazon.com.
    • A 100% petroleum jelly moisturizer.
      • Example: Vaseline®'s 100% petroleum jelly, available online at Amazon.com.
    • A moisturizer that contains triethanolamine somewhere in the ingredient list. This may be a lotion that lists glycerin as the second ingredient, after water.
      • Examples: Vaseline's intensive rescue repairing lotion, or Suave®'s skin solutions advanced therapy lotion, which is available online at Amazon.com.
    • Note: If you use the example products given, be sure to confirm the ingredients list on the product, as manufacturers might change their formulas.
  • Petri dishes, 100 mm diameter x 15 mm deep (18, or three dishes for each skin moisturizer you test plus three more for controls). A pack of 20 is available online at Amazon.com.
  • JELL-O® gelatin dessert (two 3-oz. packages are needed for 18 petri dishes)
  • Stove
  • Measuring cup
  • Cooking pot
  • Clock or timer
  • Stirrer
  • Cup with a pouring spout
  • Graduated cylinder (50 mL volume); available online at Amazon.com.
  • Refrigerator
  • Paper towels or rags
  • Scale, which must be able to accurately measure 0.1 g increments. A digital scale that is this accurate (the Fast Weigh MS-500-BLK digital pocket scale) is available from Amazon.com.
  • Measuring tablespoon
  • Optional: Plastic wrap
  • Plastic knife or butter knife
  • Clock
  • Ruler, metric
  • Optional: Camera
  • Toothpick
  • Calculator
  • Lab notebook

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Experimental Procedure

Preparing the Skin Models

In this part of the science project, you will prepare your petri dishes with the skin models (JELL-O gelatin dessert). As a control, you will prepare three dishes with the gelatin dessert only (you will not add any skin moisturizers to them).

  1. Assign a number to each skin moisturizer you want to test.
    1. Use the permanent marker to label the containers, as shown in Figure 3 below, or you can write these numbers down in your lab notebook along with the moisturizer's name.
    2. This will make it easier for you to keep track of your results.
Medical Biotechnology science project Image of skin moisturizers that are numbered.
Figure 3. Number the skin moisturizers, either by using a permanent marker to label the containers, as shown here, or by writing numbers for the names of each moisturizer in your lab notebook.
  1. In your lab notebook, also assign a number to the control samples that contain only the gelatin dessert.
  2. Label three petri dishes for each skin moisturizer you want to test, plus three dishes for the gelatin dessert-only controls.
    1. You will be testing each sample in triplicate because repeating your results like this helps show that they are accurate and reproducible.
    2. Use a permanent marker to label the edge of the petri dishes with the skin moisturizer and control numbers (do not label the lids). For each dish with the same number, also write a letter on that dish, such as "5a," "5b," and "5c," so that each dish is uniquely labeled. Figure 4 below shows an example.
Medical Biotechnology science project Diagram of an empty, labeled petri dish.
Figure 4. Use a permanent marker to label the edge of each petri dish with the skin moisturizer number and a letter so the dish is uniquely labeled. (The label "5a" is used as an example.)
  1. Follow the instructions on the gelatin dessert packaging to prepare at least 50 milliliters (mL) of gelatin dessert for each petri dish. You should prepare a little extra gelatin dessert in case some is lost while transferring it to the dishes.
    1. If you want to fill 18 petri dishes with gelatin dessert, you need to prepare at least 900 mL of it (18 x 50 mL = 900 mL).
    2. A 3 ounce (oz.) package of gelatin dessert can be used to prepare 473 mL (2 cups) of gelatin dessert. So if you want 900 mL of it, you need to prepare at least two 3-oz. gelatin dessert packages (because one package will give you 473 mL, and two packages will give you 946 mL).
    3. Prepare the gelatin dessert packages together, following their instructions. You may want to ask an adult to help you use the stove.
      1. On the stove, boil 1 cup of water per package, add the gelatin dessert mixes to the boiling water, then stir continually for two minutes (while keeping the pot on the hot burner). The mixture should look clear (but probably colored) and it should barely start boiling again after the two minutes are up.
      2. Take the gelatin dessert mixture off of the hot burner and add 1 cup of cold water per package, stirring it in as it is added. Immediately go on to step 5.
  2. Pour 50 mL into each petri dish.
    1. Use a cup with a pouring spout to ladle the gelatin dessert mixture out of the pot and pour it into the 50 mL graduated cylinder.
    2. Slowly pour the 50 mL of gelatin dessert into each petri dish (one at a time) to avoid splashing any gelatin dessert out of the dish.
    3. Work as quickly as you can without spilling too much gelatin dessert. This step can easily become messy, so try to work only over surfaces that are easy to clean.
    4. The 50 mL of gelatin dessert should fill each petri dish a little more than halfway, as shown in Figure 5 below.
Medical Biotechnology science project Diagram of a petri dish half filled with JELL-O
Figure 5. Pouring 50 mL of gelatin dessert into a petri dish should fill it a little more than halfway.
  1. When you have poured 50 mL of gelatin dessert into all the dishes, put their lids back on and carefully move them to a shelf in the refrigerator where they will not be disturbed for four hours.
    1. Move slowly and carefully to avoid spilling any gelatin dessert while you move the dishes.
    2. You can stack the dishes carefully to save space in the refrigerator.
  2. After refrigerating the dishes for four hours, the gelatin dessert should be firm. At this point, immediately go on to the next section in the Procedure, "Testing the Skin Moisturizers."

Testing the Skin Moisturizers

In this part of the science project, you will add the skin moisturizers you want to test to the petri dishes you prepared and then investigate how the JELL-O gelatin dessert and skin moisturizers change over the next two weeks. You will investigate this by weighing all the petri dishes over time (including the controls, which will have no moisturizers added) and by measuring the change in height of the gelatin dessert in the dish. You will assume that weight and height loss is mostly due to water that has been lost (i.e., evaporated).

  1. In your lab notebook, create two data tables: one like Table 1 below and a second like Table 2 below. You will be recording your results in these data tables.
  Weight of Petri Dishes
Time1a 1b 1c 2a 2c 2b 3a 3b 3c etc.
JELL-O Alone
Before Adding Moisturizer
          
0 hours           
1 hour           
2 hours           
3 hours           
4 hours           
8 hours           
16 hours           
24 hours (1 day)           
48 hours (2 days)           
72 hours (3 days)           
96 hours (4 days)           
Etc.           
Table 1. In your lab notebook, create a data table like this to record the weight over time of your petri dishes. You will be recording the weight of the petri dishes (in grams) with just JELL-O gelatin dessert, and then the weight with moisturizers over time (every few hours over the first 16 hours, and then every 24 hours after the first day), for two weeks.

  Height of the JELL-O in the Petri Dishes
Time1a 1b 1c 2a 2c 2b 3a 3b 3c etc.
JELL-O Alone
Before Adding Moisturizer
          
0 hours           
1 hour           
2 hours           
3 hours           
4 hours           
8 hours           
16 hours           
24 hours (1 day)           
48 hours (2 days)           
72 hours (3 days)           
96 hours (4 days)           
Etc.           
Table 2. In your lab notebook, create a data table like this to record the height of the JELL-O gelatin dessert over time in your petri dishes. You will be recording the height of the gelatin dessert in the petri dishes (in centimeters [cm]) with just the gelatin dessert, and then adding the moisturizers and recording the height of the gelatin dessert over time (every few hours over the first 16 hours, and then every 24 hours after the first day), for two weeks.
  1. Remove the lid from each petri dish and set the lids aside (they are no longer needed for this project).
  2. Use paper towels or rags to wipe away any gelatin dessert on the outside (such as the sides or bottom) of the dishes.
  3. Weigh each petri dish and record its weight (as "JELL-O Alone Before Adding Moisturizer") in Table 1 in your lab notebook.
  4. Using a ruler, measure the height (in centimeters [cm]) of the JELL-O in each dish, including the controls, as shown in Figure 6 below. Record this data (as "JELL-O Alone Before Adding Moisturizer") in Table 2 in your lab notebook.
Medical Biotechnology science project Diagram of a petri dish having the height of the JELL-O measured.
Figure 6. Measure the height of the gelatin dessert in each dish.
  1. Add 2 tablespoons (tbsp.) (30 mL) of the correct skin moisturizer to each petri dish.
    1. This may be easiest to do using a measuring tablespoon and pieces of plastic wrap to scoop the moisturizer out of the measuring tablespoon. (Either put the plastic wrap around your fingers to scoop out the moisturizer or you could try lining the measuring tablespoon with plastic wrap.) Use a fresh piece of plastic wrap for each moisturizer, and clean the tablespoon between moisturizers, so you do not contaminate your samples.
    2. Make sure the moisturizer covers the entire surface of the gelatin dessert in a thick layer. The layer will probably go up to around the rim of the dish, as shown in Figure 7 below.
    3. Smooth out the surface of the moisturizer using a plastic or butter knife. Use a new knife (or clean the one you re-use) for each dish.
    4. Do not forget to leave three petri dishes with gelatin dessert only and no moisturizer as controls.
    5. In your lab notebook, record any observations about how each moisturizer looks and feels. Are you surprised by the appearance and feel of any of them, based on what you know of their ingredients?
    6. When you have finished, record what time it is so that you will know the elapsed time since you added the moisturizers to the dishes.
Medical Biotechnology science project Diagram of a petri dish with skin moisturizer.
Figure 7. When you add 2 tbsp. of a skin moisturizer to a petri dish, it should fill up the dish to around the rim, as shown here.
  1. As soon as you have finished with step 6, weigh each petri dish again and record its weight as "0 hours" in the Table 1 in your lab notebook. Also measure the height of the gelatin dessert (not including the moisturizer) in each petri dish again and record the height as "0 hours" in Table 2. Keep the dishes on a flat surface while measuring their height so that moisturizer does not spill out.
  2. If you have a camera, take a picture of each petri dish at this time.
  3. Again weigh, and measure the height of the gelatin dessert in, the dishes at one, two, three, four, eight, and 16 hours after you added the skin moisturizer. Write their weights and gelatin dessert heights in the corresponding data tables in your lab notebook.
    1. If you cannot do these exact time points, write the actual time points you use (in hours) in your data tables.
  4. Then continue to weigh, and measure the gelatin dessert heights of, the dishes every 24 hours (after adding the skin moisturizer) and write the dishes' weights and gelatin dessert heights in the corresponding data tables. Do this for a total of two weeks.
    1. When you check the dishes each day, also record in your lab notebook any other observations you make over time, such as if and when the moisturizer on any of the dishes starts to develop cracks.
  5. After two weeks, make more detailed observations on how the skin moisturizer in each dish looks. Record your observations in your lab notebook.
    1. If you have a camera, again take a picture of each petri dish.
    2. Gently poke the moisturizer in each petri dish. Is it soft and cushiony, or is it hard? Is the moisturizer in some dishes cracked? Do some dishes look unchanged? Can you see the gelatin dessert below the moisturizer in some dishes?
    3. Use a toothpick to scrape away some of the moisturizer in each petri dish so you expose the gelatin dessert beneath it. Poke the gelatin dessert. Is it hard and firm, or is it soft? Try to arrange the petri dishes from hardest to softest gelatin dessert and record this order in your lab notebook.

Analyzing Your Results

In this part of the science project, you will analyze your results and determine which skin moisturizer worked the best and how this correlates with the moisturizer's ingredients. You will specifically determine the percentage of initial weight and JELL-O gelatin desert height of each petri dish over time and assess how the moisturizers changed in other ways.

  1. In your lab notebook, create a data table like Table 3 below. You will calculate the percent of initial weight for each petri dish over time and record these values in this data table.
  Percent of Initial Weight of Petri Dishes
Time1a 1b 1c 2a 2c 2b 3a 3b 3c etc.
0 hours 100%100%100%100%100%100%100%100%100%100%
1 hour           
2 hours           
3 hours           
4 hours           
8 hours           
16 hours           
24 hours (1 day)           
48 hours (2 days)           
72 hours (3 days)           
96 hours (4 days)           
Etc.           
Table 3. In your lab notebook, create a data table like this one to record the percent of initial weight for each petri dish at each time point. The weight at 0 hours will be considered 100%; it is already recorded in this data table.
  1. To calculate the percent of initial weight, first make the value at 0 hours be 100%, as shown in Table 3 above.
    1. This means that the initial weight of the petri dish with the gelatin dessert and skin moisturizer will be thought of as 100%.
  2. Then, for all following time points for each dish, calculate their percentage of the 0 hours' weight and record these values.
    1. For example, if at 0 hours a petri dish weighed 84.5 grams and after three days it weighed 75.1 grams, you would record 88.9% for day 3 for this dish. (75.1 grams divided by 84.5 grams equals 0.889, which is 88.9%.) This means that after three days it only weighted 88.9% of what it weighted at 0 hours.
  3. Next make a line graph of the data in this table. You can make a graph by hand or use a website like Create A Graph to make a graph on the computer and print it.
    1. Put the time (in days or hours) on the x-axis (the horizontal axis) and the percent of initial weight on the y-axis (the vertical axis).
    2. Make a different line for each petri dish.
      1. If you tested many different skin moisturizers, you may want to average your results from the three dishes for each skin moisturizer and graph the averages to save space on your graph.
  4. Analyze your graph.
    1. Did some types of skin moisturizers consistently (between all three dishes tested) lose more weight than other types?
      1. If some dishes lost a lot of weight, did they lose about the same percentage each day, or was there a point after which they did not lose as much weight?
    2. Did some types not lose much weight at all?
    3. How do the samples compare to the controls (the gelatin dessert only dishes)?
  5. In your lab notebook, create a data table like Table 3 above, but instead of "Percent of Initial Weight of Petri Dishes" label this one "Percent of Initial Height of the JELL-O Gelatin Dessert." Use Table 2 in your lab notebook to calculate the percent of initial height of the gelatin dessert for each dish over time and record these values in this new data table. Do this by repeating steps 2 and 3, but this time use the data from Table 2.
    1. For example, if a dish had an initial height of 1.4 cm and after three days it had a height of 1.0 cm, the percent of initial height would be 71.4% (1.0 cm divided by 1.4 cm equals 0.714, which is 71.4%).
  6. Next, make a line graph of the data in this data table as you did in step 4 above. Put the petri dishes on the x-axis and the percent of initial height of the gelatin dessert on the y-axis.
  7. Analyze your graph.
    1. Did some types of skin moisturizers consistently (between all three dishes tested) lose a greater percentage of their gelatin dessert height than other types?
      1. If some dishes lost a lot of height, did they lose about the same percentage each day, or was there a point after which they did not lose as much height?
    2. Did some types of skin moisturizer remain about the same height?
    3. How do the samples compare to the controls?
  8. Now look at both of your graphs together and any other observations you made and see if you can draw some conclusions.
    1. Do your graphs agree with each other, giving similar results for each skin moisturizer over time? In other words, did a skin moisturizer that lost a lot of weight also lose a lot of height? Do the shapes of the lines on the graph for a given moisturizer look similar?
    2. Do the results from your graphs agree with your observations from step 11 in the preceding section about how soft or hard the gelatin dessert was in the different petri dishes at the end of the experiment?
    3. Based on your graphs and other observations, which skin moisturizer(s) performed the worst in your experiment? Which performed the best?
    4. Can you explain your results based on the ingredients in each skin moisturizer?
      1. Hint: You may want to re-read the Introduction in the Background tab.
      2. See if you can find correlations between how well the skin moisturizers performed and which skin moisturizer(s) lists mineral oil as the first or second ingredient, which lists glycerin as the second ingredient (after water), which lists glycerin as the fourth ingredient, which contains triethanolamine, and which contains 100% petroleum jelly. Do your results make sense to you?
      3. If your results seem surprising, see if any other ingredients in the moisturizer (especially the first three listed) might help explain your results.
    5. What do you think this tells you about which skin moisturizer would be best to use on dry skin? What about the ingredients that you would prefer having (or avoiding) in a moisturizer?
      1. To answer this, be sure to think about how the model you used in this science project is different from what it is trying to model. For example, think about how JELL-O gelatin dessert is different from dry human skin, how often people usually apply skin moisturizer to dry hands, how much they apply to their skin, etc.
      2. If a skin moisturizer performed better than others, are there reasons someone with dry skin might not want to use it anyway? For example, does it have other ingredients that a person might not want to put on their skin?

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Variations

  • In this science project, you used JELL-O gelatin dessert as a model of human skin to test how well different skin moisturizers keep the skin moist. Can you make an even better model and test the skin moisturizers again? Hint: Think about and do some research on how gelatin dessert is similar and different from human skin, and how people normally apply skin moisturizer (e.g., frequency of application, frequency of washing their hands and possibly removing the skin moisturizer, etc.).
  • Skin moisturizers have a lot of other ingredients than the ones you investigated in this science project. Pick some other ingredients, develop a hypothesis about which ones will keep the skin model moistest, design a way to test your hypothesis, and then try it out. Tip: You may want to re-read the Introduction in the Background tab to help you pick other ingredients to test.
  • Humectants work by bringing water to the skin's surface from sources nearby. How does humidity affect how well humectants keep skin moist? Try this science project again, but this time test skin moisturizers (that have humectants) at varying amounts of humidity. You can use a hygrometer to measure the humidity.
  • After doing this science project, take the skin moisturizers that you used and ask several people to tell you which skin moisturizer(s) they like the most and which they like the least. Be sure to ask them why they like or dislike it. They can put a little bit on their skin if they want to. Does the skin moisturizer that people like the most correlate with being the best skin moisturizer based on your experiment and vice versa? Or do people prefer a skin moisturizer that did not do very well in your experiment? Why do you think this is, based on the reasons that people give you? How could you make an effective skin moisturizer more appealing to people?
  • Find several volunteers who claim to have dry hands and ask them to try a certain type of hand skin moisturizer or cream for two weeks. Observe and photograph their hands before they start using the skin moisturizer and after they have applied it for two weeks. Also ask them to take daily notes of how many times they applied the skin moisturizer and how many times they washed their hands or showered. Any other hand-intensive activities they did (such as weeding without gloves) should also be recorded. Did a certain type of hand skin moisturizer or cream work better than another one? If you used them in this science project, do your results correlate with each other?
    • If you want to do a science project involving human subjects, you should consult the rules and regulations regarding this for the science fair that you are entering. See the Science Buddies resource on Projects Involving Human Subjects to find out more.
  • Can you design your own great skin moisturizer based on your results? Look more into what the different ingredients in the moisturizers are. Then decide which ingredients you want to include in yours. Make sure not to include any potentially hazardous chemicals. You can make a few variations of your skin moisturizers and try them in this science project or you can try them on some volunteers. Are your skin moisturizers effective?
  • In this science project you used JELL-O gelatin dessert as a model of human skin to test how well different moisturizers keep that model skin moist, but what are other ways that you could keep the model moist? For example, you could prepare petri dishes with gelatin dessert and then cover them in plastic wrap, or leave the dishes' lids on. How does this affect how well they retain their moisture? Clearly, wrapping yourself in plastic wrap is not a good idea, so you would want to discuss the advantages of moisturizers to using other methods that may more efficiently keep moisture in when using a model.

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