Laundry Science Slides
Textile Chemistry
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Thread Thermodynamics
The hidden science of temperature in laundry. Why does hot water shrink wool, while cold water protects cotton? Let's zoom into the fibers!
Cold Water Hot Water
Science of Fiber Care
Under the Microscope
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What is Fabric Made Of?
Your clothing is woven from thousands of tiny hair-like strands called fibers.
At a molecular level, these fibers are made of long chains of molecules called polymers. Heat supplies the kinetic energy that can change these chains forever!
Two Main Fiber Types:
Natural Cotton, Wool, Silk
Synthetic Polyester, Nylon, Acrylic
Molecular Polymer Chains
Natural Fibers (Coiled & Interlocked)
🧬~•••~🧬
Synthetic Fibers (Straight & Heat-Sensitive)
━━━━━━━
How these chains react to heat determines their wash temperature!
Unit 1: Thread Science Properties of Materials
The Power of Cold Water
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Why Wash in Cold Water?
Cold water (below 30°C / 85°F) is the ultimate protection layer for most everyday clothing.
Fibers Stay Relaxed
No thermal stress to shrink wool or cotton chains.
Color Retention
Dye molecules stay locked inside the fiber walls instead of dissolving.
Cold Wash Mechanics
Fibers under cold conditions: Stable & Closed
Tight polymers hold shape and trap dye tightly.
Eco Fact: 90% of a washer's energy goes to heating water. Cold washing cuts carbon footprints!
Unit 1: Thread Science Safe Temperature: < 30°C
The Power of Hot Water
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Why Wash in Hot Water?
Hot water (above 50°C / 120°F) adds thermal energy that speeds up chemical reactions and physically alters materials.
Melts Fats & Oils
Seabum, grease, and body oils dissolve easily when thermal thresholds are met.
Sterilization
Kills pathogens, allergens, and dust mites. Ideal for bedsheets and towels.
Hot Wash Mechanics
Fibers under hot conditions: Expanded & Relaxed
Loose polymers allow stains to exit, but dyes can leak out!
The Trade-off: Thermal energy can damage heat-sensitive polymers, leading to shrinkage and warping.
Unit 1: Thread Science Sanitize Temperature: > 50°C
Thermal Reactions of Fibers
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Fiber Reaction Profiles
COTTON Plant Fiber
Hot Wash: Heat breaks the hydrogen bonds holding the coiled polymers. When dried, they contract, causing moderate, temporary shrinking.
Best Wash Temp: Cold/Warm (Safe)
WOOL Animal Fiber
Hot Wash: Animal hairs have microscopic shingles (scales). Heat and agitation slide these scales over each other, interlocking them permanently (felting).
Best Wash Temp: Strictly Cold & No Agitation
POLYESTER Plastic Fiber
Hot Wash: Synthetic fibers are made of extruded plastic polymers. Extreme heat relaxes the polymer molecules, causing warping or permanent wrinkles.
Best Wash Temp: Warm/Cold (Heat Sensitive)
Unit 1: Thread Science Molecular Structural Differences
Decoding the Care Label
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Reading Temperature Dots
The international laundry symbol for washing is a water tub. Inside the tub, manufacturers use dots to represent the safe temperature ceiling of the polymers.
●
1 Dot (Cold): Max 30°C / 85°F. Protects colors and delicate animal fibers.
●●
2 Dots (Warm): Max 40°C / 105°F. Standard for synthetics and blended cottons.
●●●
3 Dots (Hot): Max 50°C / 120°F. Heavy-duty cleaning for sturdy whites/towels.
Global Care Symbols
|_| Machine Wash Safe for normal wash cycles.
|_|\ Gentle Cycle Double underline means slow spin.
X Do Not Wash Fibers will permanently degrade.
✋ Hand Wash Only Extremely fragile fiber structure.
Unit 1: Thread Science Reading Labels Saves Clothes!
Ready for Investigation
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Time for a Hands-On Experiment!
We are going to test how real wool, cotton, and polyester fabrics behave when submerged in boiling hot water versus ice-cold water.
1. Measure & Cut
Draw precise squares on swatches.
2. Submerge
Expose swatches to hot vs. cold water.
3. Remeasure
Calculate shrink ratios of each material.
Get your "Fiber Heat Lab" student guide ready to record your predictions!
Unit 1: Thread Science Hands-On Investigation
Fiber Heat Lab Worksheet
Hands-On Lab Sheet
Fiber Heat Lab
Name:
Date:
Objective & Concept
Investigate how thermal energy affects the molecular structures of natural and synthetic polymers. You will measure shrinkage rates of Cotton, Wool, and Polyester after exposing them to hot water vs. cold water.
Materials Needed
✔ 3x Swatches of Wool, Cotton, Polyester (10x10 cm)
✔ Beaker of Boiling Hot Water (>65°C)
✔ Beaker of Ice-Cold Water (<10°C)
✔ Precise Ruler (cm) & Fabric Scissors
✔ Fabric Marker & Stirring Rods
✔ Tongs or tweezers
1 Formulate Your Predictions (Hypothesis)
Predict how each fiber's size and texture will change after exposure to high temperatures.
100% Cotton Swatch Prediction:
100% Wool Swatch Prediction:
Synthetic Polyester Prediction:
2 Step-by-Step Lab Procedure
STEP 1
Cut two squares (10 cm x 10 cm) for each of your three fabrics. Mark one set "COLD" and the other "HOT" using your fabric marker.
STEP 2
Submerge the "COLD" labeled swatches into the beaker of ice-cold water. Let them soak for 3 minutes, stirring gently with the rod.
STEP 3
Submerge the "HOT" labeled swatches into the beaker of boiling hot water. Let them soak for 3 minutes, stirring continuously.
STEP 4
Using tongs, carefully extract all swatches and lay them flat on paper towels. Blot dry (do not twist or wring them!).
Unit 1: Thread Science & Thermodynamics Turn page for data collection and analysis Page 1 of 2
Lab Data & Critical Analysis
Section 3 & 4
3 Measurement & Observation Data Table
Use your metric ruler to measure the swatches to the nearest millimeter. Record your values below.
| Fabric Swatch Type | Starting Size | Size in COLD (10°C) | Size in HOT (65°C) | Shrinkage % (Change/Start) |
|---|
| Cotton Plant Fiber | 10 cm x 10 cm | | | |
| Wool Animal Hair | 10 cm x 10 cm | | | |
| Polyester Synthetic Plastic | 10 cm x 10 cm | | | |
4 Analysis & Conclusions
Fiber Science Visual Guide
Visual Scaffold Support
Fiber Science Visual Guide
Super simple science explanations with picture supports.
Quick Helper
1. The Three Main Fibers
🐑 WOOL
Animal Fiber
Has tiny scales on it. Like shingles on a roof!
HEAT EFFECT:
Scales lock together like glue. Shrinks!
🌱 COTTON
Plant Fiber
Made of twisted curly strings of molecules.
HEAT EFFECT:
The curls relax, then squeeze tighter. Shrinks!
🧪 POLYESTER
Plastic Fiber
Long, smooth plastic chains melted into threads.
HEAT EFFECT:
Softens and warps or locks in wrinkles. Heat Sensitive!
2. Cold vs. Hot Wash: Simple Chemistry
🧊 Cold (Below 30°C / 85°F)
Fibers stay relaxed. Colors do not melt out. Keeps wool safe and protects dark clothes.
🔥 Hot (Above 50°C / 120°F)
High kinetic energy melts dirt, body oil, and kills bad germs. Great for cotton bedsheets!
3. Care Label Helper
●
1 Dot = Cold
Max 30°C. Protects colors and delicate wool.
●●
2 Dots = Warm
Max 40°C. Good for polyester & synthetics.
●●●
3 Dots = Hot
Max 50°C. Heavy duty wash for white cotton towels.
Hand Wash
No machines. Gentle hand squeeze only.
Quick Concept Challenge
Try to solve these with a classmate:
- Situation A: You have a dirty polyester athletic shirt. What happens if you wash it on HOT (3 dots)?
- Situation B: You spilled milk on a wool sweater. Why shouldn't you wash it in hot water?
Unit 1: Thread Science & Thermodynamics Differentiated Learning Support Card Page 1 of 1
