A Sticky Problem

A Sticky Problem Activity Card Dear Weekly Woodworker magazine, I am making a box cart and could do with some advice. I need to know: • Which glue is the strongest (in case it’s a bumpy race)? • Which glue is the most waterproof after it dries (in case it’s a rainy day)? • Which glue will clean off my clothes most easily (in case of accidents)? I hope you can help me to solve my sticky problem. Yours faithfully, Ineda Ineda Bond (age 9) Your challenge Can you help Ineda Bond to find out what kind of glue would work best for her box cart? Make and compare some different recipes for glue. Some of your fellow investigators have had some ideas to get started with. “Let’s find out about glue strength. I think we can glue two blocks of wood together and see how easy it is to pull the blocks apart once the glue has dried. We could even use a force meter to measure the force needed.” “I think we should find out if the glues can be removed from cloth. I think we could stain some cloth with different glues and wait for them to dry. Then we can stir the cloth in soapy water for a minute, squeeze out the water and see what has happened to the glue.” “We could find out about how waterproof the glues are. I think we could stick two lolly sticks together with the glue. We will find out how strong the glue is when it is dry and then after we have wet it.”

Discuss Do you think that all glues are the same? What do you think are the most important properties for glue? How are you going to test the glue recipes to find out how well they work? What will you try to stick together? What will you need to observe or measure in your tests? Getting started Now make and test your glue recipes. Remember to label your containers of glue. Recipe B Recipe A Ingredients Method 1/4 cup of water 1/2 cup of flour Add 1/4 cup of water to 1/2 cup of flour and mix until smooth. Ingredients 2 tablespoons of vinegar 1/2 cup of hot skimmed milk (or non-fat milk powder mixed with water from a hot tap) 1/2 teaspoon of Method Pour 2 tablespoons of vinegar into a cup and stir in 1/2 cup of hot skimmed milk (or non-fat milk powder mixed with water from a hot tap). Let the mixture sit for about 3 minutes. Ingredients 3 tablespoons of cornflour 4 tablespoons of cold water 2 cups of boiling water Recipe C Method Mix 3 tablespoons of cornflour and 4 tablespoons of cold water in a small bowl. Pour in 2 cups of boiling water, stirring all the time. When liquid is clear and thick, let it cool for your finished glue. bicarbonate of soda (NOT baking powder) 2 teaspoons of water Line a funnel (or sieve) with a paper towel. Carefully pour the mixture into the funnel and catch any liquid that drips through in an empty cup. You should have a solid lump collected in the paper towel. Scrape this into an empty cup and stir in 1/2 teaspoon of bicarbonate of soda (NOT baking powder) and 2 teaspoons of water. Watch for bubbles of gas. When no more bubbles can be seen, you have made glue.