- Skill Level: Novice to Intermediate
- Time to Accomplish: Approximately 1 to 2 hours
- Materials Needed: Sand Paper, Masking Tape, Sprue Cutter, #11 Exacto Knife
- A note on the abrasion listing I have. I use Micro-Surface polishing kits, the 1800 grit I have listed in the article is equal to 600 grit ANSI Standard.
Real life auto painters have a saying, “90% of a paint job is in the preparation.” This statement is extremely true in the scale modeling world. If you want that glass smooth, mirror like finish on your model, be prepared to spend some time getting the body ready for that award winning paint job.
Keep in mind also that the skills you learn prepping your model bodies can be transferred to real life cars as well. Auto shops go through the same basic procedures to get a real car ready for paint. It’s just a matter of degree.
Getting a model body ready for paint can take anywhere from 1 hour to days. The time it actually takes depends on:
- How bad the body is to begin with
- What you are trying to accomplish
The build I am going to do will be a stock build, using modeling paints. Follow along as I outline the procedure I use to prep my bodies. As a word of caution, never go on to the next step of this process until you have finished the step you are on! The effects are cumulative! So what you may overlook in the beginning CAN and will come back to haunt you in later steps.
STEP 1
Inspection of the body
I first remove the body from the kit and inspect it closely, looking for obvious molding lines, sink marks, etc. The pictures below show where the molding lines seem to show up the most. Along the tops of the fenders, and where the front and rear valance panels are molded to the body. The kit in question is a Tamiya Ferrari 360 Spider.
 |  |  |
I will check to make sure both sides of the body look uniform. I will also look at the molding of the emblems and scripts to see how crisp they are and predominate they are.
If the scripts and emblems are faint or hard to see, this tells me that they will be lost under just a few coats of paint so I will need to take this into account when I finish the body.
Look at the Instructions
At this time I will take out the instructions and look at what I can assemble onto the body before I do any painting. Scoops, fender flairs, front and rear valance panels, most of these items can be assembled onto the body after body prep has been done but before any paint is applied. This way the different parts of the body will have a uniform color and depth to the paint.
 | Notice in this picture the instructions are showing front scoops and lower body panels that need to be painted body color. While the front scoops can be glued to the body, I taped the lower body panels to the body for painting because further along in the build I will need to paint the tops of these panels to represent the engine compartment. |
STEP 3
Pre-Assembly or Test Fitting
After looking over the instructions and paying particular attention to the body assembly steps, I will do a pre-assembly. This pre-assembly is done to test fit the various body pieces to the body, the fit of the interior panel into the body, and the insertion of the chassis in the body. Masking tape is your best friend at this point.
Body
I start by taping the front & rear valance panels onto the body. If there are any side scoops or other parts of the body that needs to be painted body color then I will tape them to the body as well. For instance, the Fujimi Ferrari F355 has the side scoops separate from the body shell so I taped them inside.
Once I have as much of the body assembled as I can, I then determine if I can fit the chassis into the body. I will pay particular attention to how it fits, where it binds, and where I need to pry the body out to slip this piece in.
After I am satisfied the chassis will fit, I test fit the interior.
Interior & Windows
If the interior of your model is the platform type, (meaning it has separate sides), use masking tape to hold these pieces together to form an interior tub.
Try to assemble the interior with the masking tape in out of the way places that will not interfere with installing the interior into the body. It is also a good idea to test fit the dash panel as well.
If your kit comes with a window assembly (front, rear and/or sides as a one piece unit) then don’t forget to insert this into the body as well. If at all possible, test fit the individual windows as well if your kit comes with separate pieces. NOW is the time to discover windows not fitting inside their assigned places instead of the last step of assembly. It is much easier to correct ill fitting windows now than later.
After you have assembled the glass and interior into the body, insert the chassis again. Note any difference in fit between this fitting and the previous one (without the interior & windows). Pay attention to where the body binds with the chassis and where the body requires prying to fit the chassis into it.
Chassis
Notice how it fits and if the chassis fits snug and level in the body. If the chassis does not fit level inside the body then this must be corrected.
If the chassis is warped, sit the part in hot water (not boiling) for a few minutes then gently bend in the opposite direction of the warp. This can sometimes straighten out the chassis pan enough to allow it to fit level in the body.
If the chassis is not warped but does not fit properly, look for excessive flash on the bottom of the interior pan or along the sides of the chassis along the wheel wells. Other places that could interfere with the chassis fitting inside the body properly is a warped body, flash on the body where the front wheel wells and/or firewall is located, and around the radiator support frame.
Once all the fitting and testing is done, you will have a fairly good idea of how the kit assembles and where the binding points are on this kit.
After all the fit problems have been fixed it’s time to go on to step 4.
STEP 4
Wash the Body
It is a good idea to wash the body at this point before any sanding and/or filling is done. Run some warm soapy water (dish washing soap is fine) and clean the body and all body panels at this time.
Rinse the parts off thoroughly with cold water and let air dry.
Mold Lines
I start with an 1800 grit pad (600 ANSI Standard) and sand off the mold lines until I cannot see them anymore. I then finish this area with a finer grit pad of 2400 (about 1000 (ANSI Standard) to remove some of the sanding marks. I will do the complete body at this time. Once I compete this process I will inspect the body again for other mold lines I may have overlooked (I always tend to find some).
Sink Marks
Next it is time to fill in those annoying sink marks that seem to always be located over script or in an inaccessible spot for sanding! My personal preference is automotive spot putty. I have heard good things about Tamiya’s putty as well.
If the sink mark is deep, don’t try to fill it all at once, instead apply small amounts and let dry between applications. This will allow the putty to “gas out” and alleviate the chances of the putty “sinking” into the sink mark your trying to fill!
When I get filler into body panels (like door and trunk lines) I will immediately clean out these areas with the back of a #11 Exacto blade.
Once your putty has dried (at least ½ hr, but better at 1 hr) start sanding it smooth with 1800 grit paper. You want to get a smooth even surface between the edge of your putty and the body. Once this is accomplished I sometimes use a finer sanding pad to remove sanding marks.
Depending on how "dirty" the body gets after all this sanding, it may be a good idea to give it a bath to clean off all the plastic and body filler dust.
Perform this operation on all of the sink marks on the body. Once this is done now is the time to go to the next step.
Fitting of Panels
If there are any panels or scoops that I can assemble on the body that does not interfere with the installation of the chassis and/or interior, I will assemble them now.
If I want any of these items to look like part of the body, I will assemble them with liquid glue. Liquid glue helps to fill seams between parts and after drying allows the parts to be sanded smooth. This is not to say that you may not have to use body putty to completely fill any seams that are left. If there are any seams that you want to “do away with,” then refer to the “Sink Marks” procedure above.
Sanding in Prep for Paint
Once all sink marks are filled and sanded, all mold lines removed, pre-assembly of body panels completed, etc. I will give the body a “final” wet sanding with a 2200 Grit pad. This will assure me that the body is smooth, there are no “pimples” on the body, and give the body a texture surface for paint adhesion.
Wet sanding consists of basically sanding the body with sanding pads that are wet with water. I will sometimes sand the body under running water to keep the dust particles off it. A bucket of water can be used to rinse off the body periodically. Once you have the body nice and smooth, set the body aside and let air dry.
You are now ready to start the priming process!
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