Module 25: Automotive Refinishing and Painting (Optional)

Autobody 10, A20, B20, A30, B30 Main Menu

Module 25: Automotive Refinishing and Painting (Optional)

Suggested time: 45-55 hours Level: Advanced

Module Overview

Students will learn the procedures leading to the refinishing of a total automotive body. The vehicle to be refinished will be examined and a plan developed for repairing all corrosion, panel dents, stone chips, etc. After all damage has been repaired and the car is ready for painting, the vehicle will be refurbished using appropriate automotive paint products. It is recommended that the student has completed Module 22: Surface Preparation.

Foundational Objectives

To handle, use and dispose of materials safely.
To recommend procedures and select appropriate products for use in autobody repair.

Common Essential Learnings Foundational Objectives

To learn industry-related vocabulary and use it in context. (COM)
To demonstrate an attention to detail and standard of craftsmanship expected in the industry. (TL, PSVS)

Note: Other CELs may be emphasized.

Learning Objectives	Notes
25.1 To identify corrosion damage and its cause.	Three factors lead to corrosion: exposed metal, moisture and oxygen.
25.2 To identify and apply products that protect against corrosion. (TL, CCT)	Three types of corrosion protection are used: galvanized or zinc coating anti-corrosion compounds (petroleum-based or wax-based) paint The sequence for finishing used by the major automotive manufacturers is: use galvanized metal clean and rinse using appropriate chemicals apply conversion coating apply epoxy primer apply a second seal apply primer-surfacer apply colour coats bake colour coats apply anti-corrosion products. Procedures will include: metal treatment wax and grease removers metal conditioners (Phosphoric acid chemically cleans the metal, removes corrosion and helps prevent further corrosion.) conversion coating (Spray on surface; leave two to five minutes; rinse with water; wipe dry.) etch primer (One to two coats. Most manufacturers do not recommend the use of metal conditioners or corrosion coating before application.) two part epoxy primer. (Follow manufacturer’s recommendations on mixing, reducing and spraying.) sealer. undercoating. (optional)
25.3 To perform basic surface preparations.	See Module 6 and 8.
25.4 To identify the steps for preparing an automobile for painting. (TL, COM)	See Module 13.
25.5 To understand the uses of primer and paint.	Discuss parts of the spray gun, spraying technique, safety, air lines, compressors and advantages/disadvantages of a suction feed gun.
25.6 To use and maintain a suction feed spray gun.	Demonstrate measuring thinners, reducers and hardeners. There are three methods of measuring viscosity of paint: Ford cup (This is very accurate but expensive.) Zahn cup (A plastic cup with a hole in the bottom. The cup is filled and the time it takes for the paint to flow out the bottom is recorded.) Measuring stick. (Each paint manufacturing company has its own easy-to-use stick. Students may practise with water until they are comfortable with the process.).
25.7 To thin primer to the correct viscosity for spraying and to add the appropriate amount of hardener to the primer. (NUM)	Thinners and reducers come in three types: slow dry for hot conditions (24 degrees C); medium dry (20 degrees C to 23 degrees C); and fast dry (19 degrees C or below). Temperatures may vary with different manufacturers. Temperature is important as it affects how the paint atomizes and how it spreads on the surface being painted. All paints must be strained before being put through the paint gun. Notes Demonstrate the use of ratios to reduce paints. Refer to manufacturer’s information sheets for recommended ratios for the product being used. (IL)
25.8 To adjust the amount and choose the type of solvent appropriate for the temperature in the shop. (TL, NUM)	Paint that has had hardener or a catalyst added to it will harden in the paint gun.
25.9 To identify the pot life of paint or primer.	Acrylic enamel has a pot life of 3 to 8 hours. High solid primer has a pot life of about 3 hours. As soon as a student is finished applying a product, the gun should be thoroughly cleaned with a solvent inside and out. Failure to do so may ruin the paint gun or at the very least result in a long, tedious cleaning job.
25.10 To identify spray pattern problems, explain the problem and take corrective action. (CCT, TL, COM)	Discuss pattern problems and refer to the paint gun manufacturer’s information sheet for correction procedure. Problems that may be encountered include: cracking checking allegatoring pin holing lifting wrinkling peeling blushing runs sags crazing dirt in the finished paint bleeding acid spotting blistering dulled finish fish eyes feather edge splitting orange peel etc.
25.11 To identify imperfections in the finished paint job and correct them.	See reference materials for corrective procedures.