Fuel Tank Bodywork With Visual Impact

Published In The February 2014 Issue Of Cycle Source

Article &Photos By: Visual Impact


In our first “how to” we talked about the importance of sealing a gas tank internally, and we showed you steps to achieve a good seal job. The next step in the process to a killer paint is the bodywork. This subject seems to be glossed over or not even covered in many magazines. It seems like we instantly go from bare metal to a fancy paint job. Well, how the hell did they do it? Follow along and see what goes into a custom paint job before the paint flies.


I like to start by wiping down the part really well. Chances are there are dirty fingerprints and oils on the surface of the tank. The last thing you want is that stuff trapped under the filler and primer. This could end up being a problem down the line. Wipe the surface and dry it really well. I also like to wipe it with lacquer thinner afterwards. If you don’t have wax and grease remover, you can use lacquer thinner to clean the surface.


Next step is to grind the surface of the part. In many instances you only have to grind where you will be putting body filler. In the case of this part, like many aftermarket tanks you will encounter, it needs a little extra love on the sides. Along with the spine running up the center and the molding I will be doing on that, the logical path on such a small part is to coat it all with filler, sanding off what is not needed.


I use 36 grit on a handheld angle grinder to rough up the surface for the filler. Try to take care in grinding in the same direction as you go. Don’t just grind all over the place in all different directions. Once that is completed, blow off your part and you are ready for filler.


There are many types of filler on the market. This is one I like to use; it isn’t the most expensive or the cheapest. It flows nice and leaves minimal pinholes. All the supplies you see here are available at any body shop supplier or online as well.


Taking the hardener that is provided with your body filler, squeeze out some on a sheet of cardboard. Scoop out some filler and lay that out as well. Normally you will want to squeeze the hardener right on top of the filler and get to mixing immediately, making sure to mix thoroughly. I like to use the spreader and press down and wipe as I mix. Make sure the color is uniform and move fast.


Once you have a uniform mix you will need to move quickly and get it on your part. This stuff dries fast.


Some areas will require you to use your finger to spread on the filler.


This next step can be performed in a few different ways. You can either use a block and sandpaper or a cheese grater. I opt for the cheese grater. The idea here is to shape the filler and remove all the high spots and globs of excess as well as evening things out.


Timing is everything with this step. Too soon and you tear the filler; too late and it will be rock hard.


Once you have the filler all shaved down with your file, you will start sanding with a block and 36 grit paper. The idea here is to get the shape of the tank, remove the highs and leave the lows. The block will help with this process and keep things flat. Try to alternate directions as you cut the filler down as to not dig in. You can see most of the filler is coming off the areas that didn’t need it and staying where it was needed.


Shown here is a low spot. Note the color and how the spot has not been touched by the block.


Once you get your part shaped with the 36 grit, you will find spots that are still low. The spots will require you to go back and fill them with more filler and repeat the above steps. Once the tank is up to speed and you are happy with it, finish sand it with 80 grit.


Once you are finished sanding, take your blow gun and make sure you don’t have any pinholes in the filler. Pinholes can be fixed with more filler or you can use a good glaze. This type of metal glaze can also be used to finish the tank to fill sand scratches left behind.


This can be used directly over sanded bare metal for tiny dings or it can be used directly over sanded body filler as well. It is great for fixing sand scratches and pinholes.


The next step will be a spray body filler. There are a few ways to get a part ready for primer. The first way is to take the metal glaze shown in the last step and coat the entire tank as we did in the beginning. Sand the tank with 80 grit and final sand it with 180. The other way to get the tank ready for primer is to use a spray-able body filler. This is not the primer. This is a filler and is used to fill imperfections, sanding scratches and is great if you want to save time and get a great surface to final prime. Mix this stuff as per the instructions on the can. It dries quickly so don’t leave it in your spray gun for too long.


Now hang your part up to spray.Make sure to tape off bungs so you don’t get primer in your tank.


Use a good self etch primer on the bare metal parts before spraying the slick sand. No need to self etch the body filler, just the bare metal.


Shown with self etch on the bare metal.


Spray the slick sand on the part giving it about 10 minutes flash time between coats to dry. This stuff is thick so you will need a gun that can handle the heavy stuff. If you find some pinholes you can plow this stuff on and it won’t run like conventional primer would. It hangs on the surface really nice so it’s easy for the beginner to use, and very good for things you missed.

On a side note, make sure to clean your gun immediately after you are done. This stuff sets up fast in the gun. Forget it in there for more than 45 minutes, chance are you will be digging it out with a screwdriver.


Next, you will spray some cheap contrast on top of it for a guide coat. This aids in showing you low spots or the high spots when you are sanding the part for final primer.


The final step to getting your part into primer will be to sand the tank down with 180 grit using a sanding block and paying attention to make sure you didn’t miss any pinholes, dings or dents. You want to sand the surface till the guide coat is gone and all the imperfections are as well.


You can see how the guide coat shows you what is going on with surface. Make sure to change directions as you sand so you don’t dig into any one spot.


Chances are you will find a pinhole or imperfection that needs attention prior to prime. Mix a little glaze and fix as needed finishing the entire tank in 180 grit.


As you can see, the tank is all but finished. Final imperfections are filled.




The tank is ready to be finish primed. The final step to a beautiful finish is to prime the part. Make sure to take some self etch primer and put it on any bare metal areas. Use a good high build primer and apply three medium coats to the part allowing approx. 10 minutes dry time between coats. Guide coat and allow to dry. The end result in high build primer with guide coat on it. So there you have it. The parts are ready to be final sanded and painted. Hopefully this helped shed some light on the mysteries of bodywork and how parts are readied for the shiny stuff. Come check out some of my work and see what comes after the primer. www.visualimpact2.com or 215-868-5187

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