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Discussion Starter #81
Prime, Block & Repeat (4)

The putty will dry in about 15 minutes. Block it flat with the same 220 grit you've been using. Work your way around the car prepping and filling these small spots with putty. Address the larger spots as described, apply the prescribed remedy, when dry block it down as well.

Photo shows putty applied and blocked. Notice the 100 grit scratches are clearly visible under the 220 grit surface blocking.
 

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Discussion Starter #82
Prime, Block & Repeat (5)

Make sure doors, hood and t-tops are closed and latched. They were adjusted to fit in the foundational steps above. When blocking the edges, block flat across the gaps. You want the contour to flow across the gap seamlessly. Easy for the hood, t-tops and front edges of the doors. The hardest one on the Corvette is the lower rear half of the doors, the gap is in the edge area of a convex curve. A correct contour will have the front edge of the quarter panel slightly higher than the rear edge of the door. Be careful in this area, use the rounded block and roll it from the fender lip toward the gap. Block the door front to back, try to stay off the edge of the quarter panel.

Photo shows blocking across gaps. The door was raised to fix the upper door gap too.
 

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Discussion Starter #83 (Edited)
Prime, Block & Repeat (6)

Spot prime the blemishes and block again. Those larger low spots can use a squirt a primer too. This is my own technique, allow only one spot prime between full coats of primer. This keeps the primer thickness reasonably close to uniform. If you spot prime too much you wind up with a wavy surface and inflict more blocking on yourself. Don't forget to sand edges and recesses then check them for blemishes too.

Spot primer completed and blocked, now a second full base prime is in order. If you have taken the time to really work on the body at the stage above, the second prime will be eye opening in that you won't believe how much better the body looks. Again with 220 grit and the longest blocks possible for the areas, block it down. Mark the low spots with tape and move on. At this point try not to break through the primer down to glass. If you see the fiberglass lightening up through the primer, stop blocking that area and move on.

Again perform remedy processes to the things you missed, there shouldn't be many. Give the corrections a spot prime, plus the larger low spots another splash of spot primer and block all. It should be fairly evident why black primer is used as a base primer over the gray glass. The glass then becomes visible as the primer becomes thin from blocking. If gray primer is sprayed over gray glass this visibility is greatly reduced.

Photo shows the second coat of primer blocked and spot primer applied.
 

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Discussion Starter #84
Prime, Block & Repeat (7)

The base primer should be done at this point. Now it's time for the finish primer. Switch to the gray primer and apply a full coat. Guide coat is applied as a fog, after the primer is dry spray it from 18"-24" from the panel in big sweeping motions, cover the whole car. Now you get to block again with 220 grit. This time you will be watching the guide coat come off as you block. Low spots become much more visible because you can visually see the adjacent area has the guide coat is blocked off. Block these areas until you see the guide coat disappear or black primer starting to emerge under the gray. You shouldn't have many of these areas, usually they are around the edges of the larger low spots. Stop and move on, no need to tag as the black spot is visible. Try not to sand into the black primer, a little bit is probably OK, but if you break through to glass you gotta go back spot that with black and build up again.

Photo shows finish primer and guide coat applied.
 

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Discussion Starter #86
How guide coat works.

Blocking with 220 grit on the door area. You can see a slight low spot in the center and a scratch. The area around it clear of guide coat.
 

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Discussion Starter #87
How guide coat works.

Continued blocking shows the low spot getting smaller and the guide coat turning a lighter shade. The primer is porous so a small amount of the guide coat soaks into the primer. Block until the guide coat isn't visible.
 

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Discussion Starter #91
How guide coat works.

Time to quit and spot prime prime the low spot, add guide coat and try again. I'm sure you get the idea, remember blocks don't lie.
 

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7TRoadster, Great thread, learning a lot. I'm a long way from a novice with body/paint, but I'm certainly NOT an expert either. This part about blocking has raised a concern. I'm working an 81 that was a cherry when I found it, so I wound up with a frame off no holds barred resto mod (LS3, T-56, etc). The chassis is virtually complete, the body is a shell, and I just finished prep and paint of the underside. Body prep is just around the corner. My original intent was to refinish the components with everything disassembled. Now I'm second guessing myself. While the body is virgin (no evidence of damage or repair anywhere!) and I didn't notice any panel misalignments jumping out at me, I know how sometimes things don't go back together like they came apart. I really do not like the idea of mounting the body back on the chassis and installing all the doors, hood, headlights, etc because invariably some of the primer or color manages to sneak in to places where it shouldn't. But now I'm worried about panel fit. I want this one to be right because it will likely be my "swan song", age and health catching up with me. Your thoughts and advice would be greatly appreciated!









 

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Discussion Starter #93
Well, you certainly have done an outstanding job on everything I see in the pictures. Nice Work!!!

The factory fit usually isn't as nice as we all want our cars to be. Most of the assembly/body manuals I've read on these older cars say plus or minus a thirtysecond. In reality it's more like plus or minus a sixteenth. Not many check this before disassembly and have no way of knowing what it actually was.

My opinion on body panel fit is they need to be absolutely flat across the gaps. If you stand in back of the car looking right down the side and you can't see the gaps, the contours and reflections are contiguous then you know it's right.

The only way to fit them accurately is to do body work and panel matching with them assembled on the car with weight in place. Body bolted down, motor and trans installed, window regulators and windows in place and car sitting on all fours.

This usually means taking them off the car for stripping, back on to do the body work, off to spray the jams, back on to spray the finish coats. Plus all the masking in between.

It's not easy to remove and replace doors unless you have a door dolly (Door Lift). At the time I bought mine they had them at Harbor Freight for $125 or so, I don't see it listed for sale now. Northern Tool has an inexpensive one although reviews aren't the best.

https://www.northerntool.com/shop/tools/product_200370076_200370076?cm_mmc=Google-pla&utm_source=Google_PLA&utm_medium=Automotive > Auto Body Repair > Parts Holders&utm_campaign=Torin Big Red&utm_content=805001&gclid=EAIaIQobChMIuNvXoLjx3wIVkSCtBh1h9AFUEAQYBiABEgJ3rfD_BwE

Anyway, once the doors are fitted and adjusted only remove hinges off the body, leave the hinges on the doors tightened down. Be sure to tag and bag the body shems separately. Keep them together in the exact order and placement. Mark which side faces outward and which side forward. If you put them back in the exact way they were removed you will be very close to the same place. The only variables then are the height of the door in the jam and position front to back. Use the dolly to raise it up or down as needed. Once fitted, a quick block with 600 across the gap and you should be good to spray the finish coats.

I'll be covering some of the masking tricks later on in the thread but for now lay a layer of plastic down over the chassis before you mount the body. Keeps overspray off of all, when done you can remove it without removing the body.


Tips:

Tape the edges of the doors and jams with masking tape to keep them from chipping the other edge should they touch.

A wet coat of wax & grease remover gives a glimpse of finish shine before it evaporates. This allows you to inspect how the paint will look on the body before you paint.
 

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I was afraid you were going to say that, but of course you are 100% right. I did keep the body shims and left the door hinges attached to the door, unmolested.



Your suggestion to wrap the chassis in plastic and then mount the body is brilliant! Man, I never even thought of that! A great solution and right there in front of me yet I couldn't see it.


I will definitely check into the door dolly. I have access to 4 "indentured servants" (read sons!) but I've been down that road several times. Even with lots of people things can go south in a heartbeat. I remember a job I did back in the mid 70's where we had to remove/replace a door on a 73 Monte Carlo. Now that was one %$#@ heavy door!


And another one I never thought of: Using Prep-Sol or First Clean ( or equivalent) to leave a temporary wet shine. So simple yet I never thought of it!


I'm going to sleep on it but right now I'm leaning toward mounting the doors and hood as you say. No matter how much of a PITA it is, it's the only right way.


Thanks again!
 

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Discussion Starter #95
Prime, Block & Repeat (8)

Getting back to the paint work. You have primed with finish primer, blocked it with 220 grit and exposed low/high spots. You have blocked those down to black primer, spot primed the low areas or repaired as previously described. Be sure to scratch it up good with 100 grit if you have to add putty. Again one spot prime of the trouble spots and blocking between full coats of primer. At this point the car is starting to show contours really well, flattening out really nice with flowing curves. Time for another coat of finish primer. Spray it on there and give any stubborn trouble spots an extra layer.

Photo shows first coat of finish primer blocked with 220 then spot primed, but before guide coat was applied.
 

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Discussion Starter #96
Prime, Block & Repeat (9)

Spray on another application of guide coat and now switch to 400 grit for blocking. The change to 400 grit is dramatic as the primer blocks slower, guide coat is basically lacquer primer so it's going to stick in the finer papers a bit. Use a scotch cloth pad to remove the buildup. Block the whole car with 400 grit, takes about 12 hours. Most all of the low spots should already be filled and block out before hitting any black primer. The previous blocks with 220 grit should have brought the body very close to contour. If you bump into any that don't, spot prime them add guide coat and block again. This stage is why I only spot prime one time between full coats, if you have 3 or 4 layers of spot primes the car won't block out as well with 400 grit. You will wind up with larger crescent shaped low spots around the areas of repeat spot priming and you get to block those out with 400 grit, which takes forever.

Your goal at this point is to block the whole car with 400 grit, removing all the guide coat without breaking through to the black primer. It seems there is always a small spot or two on corners or edges that will show black. Lightly spot prime and block those again. If you're finding larger spots in multiple places there was an error at a lower level in the substrate and you can't just keep adding primer. Go back to 220 and block the car down to where you have black showing consistently in most areas. Spray a full coat of finish primer and block again with 220, spot prime, spray guide coat, block the spots, spray a full coat of primer, guide coat and start with 400 grit again. This is pretty common for novice guys who are learning to block or haven't developed good technique but it's how you learn that technique is important. By the time you have done one or two like this you will have figured it out. LOL..... Experience is a tough teacher, you get the test first then the lesson.

Photo shows car blocked with 400.
 

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Discussion Starter #97
Mask and Prep for Paint

The car has been blocked successfully with 400 grit blocks. As you stand back and look you won't believe how great the contours look. But it's time to consider how colors impact decisions for final preparation before painting. 400 grit scratches will successfully fill with single stage solid colors. Some single stage paints with fine metallics will show 400 grit scratches. Almost all base coats with fine metallics will show 400 grit scratches. Some colors tend to hide them but generally they will show. Base coat solid colors are much more forgiving with only a few of the colors showing 400 grit scratches. If in doubt spray 3 applications of color (following flash times) on a test panel and check the results in sunlight.

If you have chosen a single stage solid color you can spray over the 400 grit scratches. If you have chosen a metallic single stage or solid color base/clear coat, prep & spray a test panel, if you can't see scratches in the results you can spray over the 400 scratches. If you have chosen metallic base/clear coat as this customer did or you can see scratches in your test panel, you will need to block with 600 but not until after door jams are painted and cleared.

For this car the customer has chosen a very fine metallic silver. Silvers and golds are IMHO the hardest colors to spray. It's very hard (for most painters including me) to get the metallics in the paint to lay even and consistent over the whole car. The technique to do this is advanced and I'll do my best to explain the technique a little later on. Most shops will say black is the hardest color to spray, it's not spraying the color, the issue with black is that it requires the body and substrate to be perfect in order to look good. If you're considering a shop or individual to do body work, ask to see a car they did that is painted black.

Prepping the door, hood, t-top or clam shell jams is easier than elsewhere because normally you won't consider contours critical. Two coats of base primer applied to these areas are adequate. Most areas are small for blocking but I use a short piece of smooth hardwood for a block, some are shaped with a sander to fit into rolled edges or narrow spaces. Some tight places sand paper is cumbersome, use a fine (gray) scotch cloth to scuff those areas. As long as the paint has scratches to promote adhesion you're good to paint over a fine scuffing. Don't let grease on the hinge pins contaminate the scotch cloth.

The best way to paint door jams, inside of the door, body jams, recesses and body is to paint them all at the same time. The doors are hung in the booth or on stands, hood laying flat on a stand, t-tops laying flat, mirrors on a stand, etc. It is important if spraying metallics to have the panels oriented as they are on the car so the metallic settles as it would on the car. The problem is that my paint booth (14'x22') isn't big enough to accommodate that method. Temperature and humidity can also impact how paint reacts to application so spraying them on different days is risky. Solving of this problem requires spraying the jams and recesses first, assembling the car, mask these areas off and spray the body assembled. There are some additional cautions associated with this method that will be covered later in the blog.

Notes on these door jams: This customer was adamant that it was not necessary to do the extra work required to remove and reinstall the doors. Due to the difficulty in stripping, bumper replacements and hidden damage the project is running over budget. The customer wins this one and the door jams were sprayed in place.

With the door jams prepped it's time to remove the primer masking. It will be full of sanding dust and any number of other offensive substances like dead insects, paint chips, scratch pad droppings and boogers. Try to roll the plastic up as you remove the mask, all of it, any tape that has primer on it too. Blow out all the cracks and crevices with air real good, including the threads of bolt and screw holes. You do not want to atomize a pocket of dust while spraying paint or clear. Wash the car again with dish soap and water. Blow water out of crevices, let it dry completely.

Photo of primer masking removed.
 

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Discussion Starter #98
Mask for Paint

Apply and remove wax and grease remover (or equivalent). It's important to do wax and grease before you mask for paint. If wax & grease touches the sticky side of masking tape then gets rubbed on the car it will leave fish eyes. Lots of them.... If you do have to clean after masking, be very careful not to let wax & grease remover touch the masking tape.

Body shops have a line item called 'precision masking', the careful line between paint and whatever you don't want painted. The look of an otherwise great paint job can be ruined by poor masking. For example: sloppy masks on edges can leave a previous color showing through or a line where color was sprayed over stainless.

Let's examine masking for a bit. Four types of masking are typically used, they are likely called a ton of different names. Here is what I was taught: no line mask, hard line mask, soft line (back mask) and a folded/gap mask. All are used on this car. The no line mask is basically masking behind what you intend to spray. It was done to mask the engine area and interior around the inside edges of the door jams for primer. Hard line masks are generally used to mask stainless steel, window edges, graphic lines use hard line masking, but use a thinner vinyl tape. Soft edge masking provides a soft edge between painted surfaces. Used for masking the outside edges of door jams if they have been painted separately from the outside of car. The folded mask is use in areas that are hard to access but still need masking to limit over spray.

No Line Masking.

Applied to the opposite side of what you intend to paint leaving the sticky side up to accept plastic or paper masking media. Great for engine areas, internal door jams, around grilles or vents that have an exposed inside edge.

Hard Line Masking.

Named as such because it leaves a hard edged line of paint when removed. Sticky side of tape is applied directly to the surface with masking media stuck to about half the width of the tape. Great for masking stainless, windows, mirrors, trim, anything with an abrupt change from paint to it's surface.

Soft Line or Gap Masking.

Stuck to the surface to be protected then folded back leaving a rounded edge that tapers away from the surface then is curved back over the top of the protected surface. This rounded edge will leave a soft edge when paint is applied over it.

Folded or Gap Mask.

Lay a piece of masking tape sticky side up on a flat surface, lay another piece of tape on top sticky side down and off set about 1/2 the width. Fold one of the offset sides over the edge of the two mated surfaces. You now have a piece of mask with tape along one edge but is not sticky on the other edge.

These are used in gaps that are inaccessible, like the front door edges. Stick it on one side with the door open and push the other half inside as you close the door.

These are illustrated in the drawing below. Pictured left to right are hard line mask, back mask and gap mask.

Materials are shown in the primer mask posts above.


Tips:

Vinyl or fine line masking tape is thinner and is better suited for masking graphics.

The 1/8" fine line tape works great in tight corners, stretch it a little as you apply and it will go around the corner without a wrinkle.

Vinyl tape works great if you're masking wheels or stainless for paint.
 

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Discussion Starter #99
Mask for Paint

The first half of masking is for painting the body door jams, door jams, hood jams, t-top jams, tail light recesses, side marker light recesses, fender edges, front and rear bumper recesses. I like to paint recesses first, because it's hard enough to lay down an even coat without having all the additional spray from recesses and fender edges. If you're spraying all at once spray the edges and recesses first.

We are going to use no line masking under the hood, light sockets and around the cab recesses. Hard line masking on the mufflers, tailpipes and the frame. Mask the areas described in the primer masking section. Mask off the inside of the doors under the door panel with hard line mask. I'm confident you can figure out the rest.

Photo of jam masking completed
 

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Discussion Starter #100 (Edited)
Paint Materials

Here is a photo of the paint materials. Use good quality paint, 3/4 of a gallon of paint, mixed at 2:1 with reducer gives just over a gallon sprayable. About right for this small car even with jams. When shopping for paint pay attention to mixing ratios and sprayable yield. USC 7500 clear and the temperature appropriate catalyst is an above average high solids clear, it represents a good value (yield 2 gals). You can spend allot more on clears with not much more bang for the buck. The USC with catalyst is about $200, Valspar's top of the line clear with catalyst is over $400 for a little over half as much. The main differences are flow out and atomization qualities, both important but become less so if a good gun is used to spray them.

The age old conundrum of quality vs cost. You are the only one who can make those decisions.

Other things you're going to need, mixing cups, paint filters, mixing sticks, lacquer thinner for clean up, a quality respirator, tack rag and a shoot suit.

Ninety percent of dirt, dust and lint in finished paint comes from the painter. A good way to reduce this is a shoot suit or body condom as we call them. They are about $50 at Summit and are a great value. You can usually get 5 or 6 uses out of them before a new one is required. They clean up great, just wipe them down with lacquer thinner and let them dry.
 

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