Paint Your Wagon

Part 4 of the "Get a Wedgie" TR7 restoration series

Well we have now entered Part 4 of Get a Wedgie with the overview of the painting stage. The actual painting process becomes secondary to all of the preparation work. For this project, there wasn't a whole lot of "mud" work (also called filler or "Bondo" but I use much higher quality fillers than that). Other than the arch replacements, you saw about all there was for dents and such which left little else to document in this area. We may cover "mud" work in a later article or clinic.

There are numerous stages to painting a car, especially when it has received a bare metal strip like I did with this car. Several types of primers and paints are used, each requiring their own reducers, activators catalysts, etc. What? All that means is that you switch into being an amateur chemist for a while as you mix the various potions together to get your primer and paint correct. When painting a car, you almost have to work backwards in selecting the proper paints and primers. This is because they all need to be compatible with each other. If they are not, then nasty things occur such as peeling and lifting of the underlying surfaces. Not fun considering all the time you spent preparing the car. In the case of this TR7, I am using all PPG paint products and the names in this document refer to their product line. I've been very happy with the ease of use and the compatibility ranges the PPG product line has. The final top coat was going to be an Acrylic Enamel, so all of the previous primers will need to compatible with the enamel.

All primers and paint were applied using a special HVLP paint system, or High Volume Low Pressure. This is a very desirable way to paint since there is very little overspray, almost all of the material you spray hits the body work, no worries about oil or water in the air supply. You tend to use less paint since you are not suspending or "bouncing" the paint in the air like a conventional gun at 45 psi. A HVLP sits around 3-4 psi but at 60-80 cfm! If your going to HVLP, get a whole system. There are guns that are advertised to work with your standard compressor; well they don't work well and you still have to deal with water and oil traps.

Step One: Once all of the filler and sanding of the bare metal is complete, the first primer coat I shoot is an epoxy based primer called DP402. DP402 is mixed with its matching catalyst to activate it. I use this product since it has a double use. First it provides a bare metal base coat for your sandable primers. Second when reduced it can be used as a sealer coat, but more on this in a moment. This primer is not intended to be sanded as it is a relatively "hard" coat. Before you spray liberally wipe the surfaces with DX330 grease/wax remover. Grease? Yes, the oils from your hands are enough to cause problems. Generally you spray 1-2 coats as is it only intended to provide a base for the next primer. Unless you are painting metal that has never been sanded or painted before, there is no need for an etching primer (as told to me by a auto painting professional).

Step Two: The next type of primer can be called by several names. Sometimes it referred to as sandable primer, primer surfacer, and filler/builder primer. I use K36 and it come's in several colors depending on preferences and subsequent topcoats. I'm using a light gray for this project. K36 also comes with a catalyst/activator and can be reduced depending on the thickness of the coverage you want. Oh by the way, the reducer for K36 is the same for DP402 which helps reduce your materials cost. This type of paint is sprayed on with several coats as its intent is for you to start to fill in sanding scratches and is soft enough to start the first block sanding of the car. Again, before you spray, liberally wipe the surfaces with DX330. The reason you lay down the DP epoxy primer is that sandable primer, while it does adhere to metal, it does not really "dig" in. However it does "dig" in nicely to the epoxy. What you want these layers to do is to bond to each other and that's why its important to make sure they are compatible with each other. "Block" sanding is the process of sanding out ripples, "assholes" (these are the round areas around filler repairs) and other imperfections. You will be wet sanding with nothing coarser than 400 grit. How well you did with your filler repairs, reflects on how much sanding you will do here. Block out the entire car. Sounds strange to paint and then sand it off, but you will find yourself doing this several times. You may have additional minor filler repairs. If you find yourself mixing up batches of filler again, you may have been a little premature with the primer. Once you get the knack of this, repairs are handled using "spot putty". This is a soft very sandable "filler" that comes in a tube. Finding imperfections are equal in terms of seeing and feeling them. It's all experience here, you'll be going through several paint jobs before you are really good at it.

Step 3: Getting close, assuming you are reasonably assured that all of your imperfections are "blocked" out. You will once again mix up a batch of DP402 but this time adding about 1 part of reducer. This mixture acts as a sealer coat over your primer surfacer. This serves two purposes, first as a barrier from any "bleed through" of the primer surfacer into you topcoat. Second, remember that the primer surfacer is a bit "soft". We need a more solid surface for your topcoat to adhere to and the sealer coat provides that. Again, before you spray liberally wipe the surfaces with DX330. Once at this point, you should not be doing any additional sanding or repairs.

Step 4: Paint time! As mentioned earlier, I selected an Acrylic Enamel system called DAR. The cool thing about DAR is that PPG also has a clear coat for this surface of which will be applied. Why is this cool? Well as you know most of our Triumphs were painted using solid colors. The problem with many base coat/clear coats is that many base coats are metallics (that's the shiny stuff in the paint). Not desirable if you want originality. Anyway paint is mixed using the base color, a temperature based reducer and a activator. There are temperature ranges built into reducers that control the drying rate. Too fast, you get orange peel, too slow you drip. This is a big experience thing here and we will discuss details about this during an upcoming clinic or meeting presentation. Because this TR7 was being painted black (the hardest color in the world to paint!), figure doing at least 3 paint/sand cycles. Yes I painted the car, wet sanded it, painted another coat, wet sanded it, painted another coat, and wet sanded it with a final 1500 grit.

Step 5: The final material on the car is the Acrylic Urethane clear coat. I applied 2 coats of clear. This uses the same activator as DAR. The nice thing about clear coat is that the dull surface caused by sanding (or base coats for that matter) is nice and bright once the clear is applied. The other nice thing is that clear flows very nice over the paint.

Step 6: This is for next spring. As amateur painters, we don't have the luxury of 100% dust free environments. So the final step is to take 1500 or 2000 grit sandpaper and wet sand the dust and any bugs that landed in the clear coat. You then buff her out and hopefully the fruits of your labor will be worth it. A nicely painted Triumph that still leaks oil in your driveway.

Project Totals
           Current Phase      Totals to Date
Hours:	        75.5              212.5
Costs: 	      $606              $1059.72

DP402         $187
K36           $190
DAR           $229

By Joe "Stagmeister" Pawlak

Copyright © 2001 Illinois Sports Owners Association