What is Putty made up of?
The Purpose of Putty
Putty is a paste-like material used as a filler. Its primary job is to fill minor imperfections such as cracks, holes, and open joints in a surface (commonly wood) before painting. To be effective, it must be soft and pliable enough to be pushed into gaps, but also capable of hardening over time to create a solid, sandable surface. Its composition is a simple combination of a solid filler and a liquid binder.
📝 Detailed Analysis of the Options
(a) Red lead and linseed oil
Analysis: This combination forms a traditional, highly effective anti-corrosive primer for iron and steel. Red lead is a pigment/base, and linseed oil is the vehicle. While it forms a paste, it is a paint primer, not a filler putty for general surface preparation.
(b) White lead and turpentine
Analysis: White lead is a paint base (a solid powder), and turpentine is a volatile solvent (a thin liquid). Mixing these two would create a thin, fast-drying paint, not a thick, slow-hardening paste needed for putty. There is no proper binder to hold it together and form a durable mass.
(c) Powdered chalk and raw linseed oil
Analysis: This is the correct answer. This is the classic, traditional formula for painter's putty or glazier's putty.
- Powdered Chalk (Whiting): This is finely ground calcium carbonate. It acts as the inert solid filler, giving the putty its body and paste-like consistency.
- Raw Linseed Oil: This is a slow-drying oil that acts as the binder. It coats the chalk particles, making the mixture pliable and sticky. Over time, it slowly oxidizes and hardens, turning the soft putty into a firm, solid mass that can be sanded and painted. The slow drying time is crucial as it gives the user ample time to work with the material.
(d) Zinc oxide and boiled linseed oil
Analysis: Zinc oxide is a paint base, and boiled linseed oil is a fast-drying vehicle (it has driers added to it). This mixture would create a fast-drying paint or cement. While it could be used as a filler in some cases, it would harden too quickly and become too brittle for use as a general-purpose putty, which needs to remain flexible for a longer period.
📊 Putty Components vs. Paint Components
| Component | Role in Putty | Role in Paint |
|---|---|---|
| Chalk | Primary Filler/Body | Extender / Filler |
| Linseed Oil | Slow-drying Binder | Vehicle / Binder |
| White/Red Lead | Not used | Base / Pigment |
| Turpentine | Not used | Solvent / Thinner |