Hopefully my notes from class help you
The 100-grit Rule
-Thou shall not skip more than one hundred grits more at a time
-If you sand with 80, you must sand with 120 in order to sand with 220 to prepare the panel with high build primer
-Skipping grits will lead to shrinking; a few weeks after the car is painted it will come back with scratch marks in the finish. This is caused by large sand scratches under the primer that are temporarily hidden until the primer fully cures
-Use a powdered or liquid guide coat to highlight coarse sand scratches, and this will assure you that you have removed the scratches from the previous grit.
-Over 600-grit the one hundred grit rule does not apply because the next grit is 800.
-You should still not skip grits. 800 should be followed with
1200->1500->2000->3000
Evaluating the Existing Surface
• We must check the existing surface to determine if it is going to be good enough for our new paint to stick
• First you must check the thickness of the old paint, must be less than 12mills
• 1mill is 1/1000 of an inch
• Paint thickness is measured with a magnetic or electronic paint thickness gauge
• OEM paint is approx. 6mills+6 mills of aftermarket paint= 12 mills
• Typically if a panel has been repainted once, painting over it a second time will void the paint manufacturer’s warranty
• Check the old paint for good adhesion, look for excessive chipping, peeling, corrosion, cracking and lifting
• Use a razor blade to pick at any suspected edges on the paint or use a blow gun at high pressure close to the surface
• If any of the paint comes off easily, the affected area must be stripped
• Perform a solvent test on the old paint to determine if it is 1K or 2K
• To do a solvent test pour a small standing puddle of reducer on a horizontal surface and let it sit for a few minutes
• Use the paint reducer from your paint system (gun wash may be too aggressive, wax and grease remover may be too mild) Use the reducer for the first product you are going to be applying over the old paint
• Rub a clean rag into the standing puddle aggressively. (If the paint is dark use a light rag and vice-versa)
• If the paint film, smears, melts, swells or comes off in anyway, the finish is 1K and must be stripped (or is not compatible with your paint system)
Fix’n A Run
• To save time we shave the run down before wet sanding
• Shaving can be done with a new razor blade held to surface at 90 degrees and drawn over the run (a nib file works well too)
• Protect the surrounding paint with a strip of masking tape on each side of the run
• The run should only be shaved down 80-90% of the way
• Remove the remaining 10-20% with fine wet sand paper and a rigid sanding block
• Finish sand the repaired area with 2000-3000
• Buff to a shine
How We Wash a Car in the Body Shop
- Pre Repair- Decontamination
- Soak with lots of water from the top down
- Start from inside out (vehicle jams, under hood, etc.
- Soap and water (strong detergent, nothing fancy)
- Rinse with lots of water, top down
- Soap and water again
- Final Rinse
- Silicone and Wax Remover (Pre-Kleeno)
- Wipe On, Wipe Off 1. Post Repair- Make pretty for customer
- Soak with lots of water from the top down
- Inside out (clean interior, vacuum, wipe down dash, etc)
- Use the fancy soap
- Rinse from top down
- Soap and water again
- Final rinse
- Dry
- Windows (inside and out)
- Engine shampoo
Detailing
- Start by vacuuming the interior and trunk, wipe down interior plastics, clean inside windows
- Clean vehicle jams, front end damage- engine shampoo, rear end damage- spend extra time on the trunk
- Use super fancy auto soap, rinse and repeat
- Dry vehicle with shammy or terry cloth, use spray for extra shine
- Check entire vehicle for water leaks
Masking
• Keeps paint from contacting areas that are not meant to be refinished or painted
• Four Basic Ways to mask:
• With masking paper and masking tape
• With plastic sheeting and masking tape
• With specially shaped cloth or plastics covers (for wheels, antenna and rear view mirrors)
• With liquid masking material
Required Qualities in Masking Products
• You should be able to mask a vehicle as cheaply and efficiently
• Tape must be sticky enough to stay on during bake cycle, but not so sticky to peel off fresh paint
• The most expensive, fancy masking products might be overkill, cheaper products that get the job done are fine
• Make sure the masking materials are compatible with your paint system
• If you know ahead of time that the vehicle is not going to be baked, or painted with solvent paint, you may be able to use cheaper tape to mask that vehicle
• Some masking paper that is not approved for water borne paint will work if you turn the paper inside out
• Aggressive industrial coating can soak through regular masking
• The masking products and procedures must be quick and easy
• A vehicle that is only getting two panels painted is cheaper to mask with expensive plastic rather than cheap because of the saved time
• Things like masking stands, spray mask and wheel bags are a larger initial cost but save so much time that they quickly pay for themselves *Return on Investment
• Efficient planning and knowledge of the entire refinish process essential
• Most shops will have an experienced and high paid person doing the masking. This is more cost effective due to the efficiency of the experienced employee
• If the painter is not doing the masking, the person who is will be in direct communication with them
Buffing
• The two main reasons for buffing: Restore an old finish, fix a new one
• A freshly painted vehicle should be examined in a well lit area (ie. Spray booth or outside)
• Mark any flaws like runs, dirt, dust, orange peel, bugs with a paint safe marker or masking tape
• File flaws out with a nib file first (always wipe off file after each piece of dirt is removed)
• Water sand with 1200-1500g (use a squeegee to check you progress)
• Move to 2000g to finish sand the area
• Buff with compound and a wool pad
• Wash the surface to remove any compound residue
• Final buff with a foam pad and machine glaze to desired
Feather Edging
• Tapering edges of the damaged area with sandpaper or special solvents
• Sanding the damage out and creating a smooth tapered ramp up to the rest of the finish
• Sand the damage (120-220) Creating a taper (ramp) through the existing finish to remove the damage. Each layer of tapered paint or primer must be 3cm wide to ensure the repair will be invisible
Repairing a Chip
• Use proper paint according to the finish on the vehicle (bc/cc)
• With a dab of colour on a fine paint brush or a toothpick or a pin work well. Allow a small drip to form on the tip
• Carefully push the puddle of paint on the bottom of the chip to the sides, once close to the side the puddle will grab on to the sides
• One coat of the colour is all it takes
• After the colour is dried, fill up the chip with several coats of clear using the same technique
• Build the clear up higher than the surrounding surface and allow to dry over night
• Water sand and buff and the chip is gone
To Strip or Not to Strip
• Is the old paint over 12mills thick?
• Does the old paint adhere well to the surface?
• Is the old paint 2K activated?
• Is the old paint chemically compatible with the new paint?
Work Orders
• Compare work order or estimate to repaired vehicle
• Headlight alignment
• Check that A/C works
• Check vehicle lights
• Check cluster for engine lights, SRS, ABS etc.
• Check vehicle accessories: wipers, heater, defrost, power windows etc.
• Check all seatbelts are in working order
• Drive car, feel for pull, listen for unfamiliar noises, wind whistle
• Radio presets
• Work orders contain vital information for the technician working on the vehicle
• The work order must be present for the vehicle being worked on in the shop for insurance reasons
• The work order contains the VIN, License plate, mileage on the ODO, Paint Code, Make, Model, Year, Date it Entered the Shop, Owners name and phone number