engineering

Putty

Putty is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Putty rather than just read about it. In short: Putty is a material with high plasticity, similar in texture to clay or dough, typically used in domestic construction and repair as a sealant or filler. Although some types of putty (typically those using linseed oil) slowly polymerise and become stiff, many putties can be reworked indefinitely, in contrast to other types of filler which typically set solid relatively rapidly.

Key takeaways

Putty belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Putty to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Putty from memory before moving on to harder problems.

Reference excerpt

Putty is a material with high plasticity, similar in texture to clay or dough, typically used in domestic construction and repair as a sealant or filler. Although some types of putty (typically those using linseed oil) slowly polymerise and become stiff, many putties can be reworked indefinitely, in contrast to other types of filler which typically set solid relatively rapidly.

Chemical composition Putty, or lime putty, is made from a mixture of calcium oxide (CaO) and water (H2O) in proportions of 38% and 62% by weight respectively. As a result, the solution forms hydrated lime (Ca(OH)2) which takes up about a half of the weight. The other putty mixture may be a calcium carbonate (CaCO3, 750-850 parts) based with an admixture of CaO (ash calcium, 120-180 parts), white cement (40-60 parts), and talc powders in much lower concentrations (fractions).

Applications

Use in construction Putty has been used extensively in glazing for fixing and sealing panes of glass into wooden frames (or sashes), although its use is decreasing with the prevalence of PVC and metal window frames which use synthetic sealants such as silicone. Glazing putty is traditionally made by mixing a base of whiting (finely ground chalk) with linseed oil in various proportions. Historically, white lead was sometimes mixed with the whiting. There are a number of synthetic alternatives such as polybutene-based putties, where the polybutene is a low molecular weight oligomer replacing the linseed oil. Butyl rubber is also added to the mixture to provide some strength and flexibility. Painter's putty is typically a linseed oil-based product used for filling holes, minor cracks, and defacements in wood only. Putties can also be made intumescent, in which case they are used for firestopping as well as for padding of electrical outlet boxes in fire-resistance rated drywall assemblies. In the latter case, hydrates in the putty produce an endothermic reaction to mitigate heat transfer to the unexposed side. In woodworking, water-based putties are more commonly used, as these emit very little odour, are more easily cleaned up and are compatible with water-based and latex sealers.

Two-part hardening putties Polyester putty and epoxy putty are thermosetting polymers that can be molded by hand, but become permanently rigid after curing. Pratley Putty is an epoxy putty used primarily for steel bonding. Milliput is another popular multipurpose epoxy putty. Bondo is a polyester-based automotive body filler, which is commonly used in collision repair.

Plumber's putty Plumber's putty is the common name encompassing a variety of products of completely different compositions, all used for making watertight seals in plumbing. It is a pliable substance used to make watertight seals around faucets and drains. The putty is a basic component of a plumber's toolkit and is often used when replacing plumbing fixtures. Plumber's putty formulations vary but commonly include powdered clay and linseed oil. Other formulas use limestone, talc, or fish oil. A similar material known as Tung putty, made from lime and tung oil, is used in plumbing and a waterproof sealing in Chinese cultures. Plumber's putty contains mineral oils and/or vegetable oils so it can stain porous materials such as marble or some plastics. The oils can also react chemically with some plastics, slowly making them brittle. RTV silicone or epoxy sealants may be used in place of putty.

Other uses Certain types of putty also have use in the field of terminal ballistics, where the putty can accurately represent the average density of the human body. As such it can be used, for instance, to test the penetrative power of projectiles, or the stopping power of body armour. Modeling clay and play putty, such as Plasticine and Silly Putty are common toys.

See also Blu Tack Caulk Grain filler Rope caulk Spackling paste Tung putty Wood putty Whitewash

References

"Putty" . Encyclopædia Britannica. Vol. 22 (11th ed.). 1911. Putty & Mastic at wiki.DIY FAQ.org.uk

Worked examples

Example 1 — a first encounter with Putty

Start with the simplest possible case. Write down what Putty claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Putty before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Putty ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Putty

In research: Putty appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Putty in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Putty is common in secondary-school and first-year university syllabi. It links to neighbouring topics Firestops, Materials, Passive fire protection, so understanding it makes those chapters shorter.
In everyday life: Look for Putty outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Putty in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Putty means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Putty out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Putty in simple terms?

Why does Putty matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Putty?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Putty.