Post by jwrass on Feb 11, 2017 12:19:40 GMT -5
Surface Prep 101
I have read and seen many purple pond stories and paint issues on numerous forums and I sympathize with the frustration that many have when it pertains to achieving a successful paint finish. This is going to be a multi part tutorial that will take us from start to finish obtaining that perfect finish. My approach may seem a bit unconventional for modeling as I use processes and procedures that come from my 45 years plus experience of custom painting in the 1:1 arena. I am not going to claim that my way is the right way or the only way. I believe these are sound principals, they work for me. It is my hope this will help the community as a whole…… let’s begin.
IMO 90 ish % of paint problems start when the kit comes out of the box! Just as a home needs a good foundation so does a paint finish, preparation and products are key:
A) Cleanliness is key….. All bodies contain contamination in the form of mold release. Before you start sanding, filing, cutting chopping Yada Yada the subject has to be absolutely clean, I soak my bodies overnight in a clean container of Purple Power (not the same one that you may use for stripping) I do this for Styrene and Resin. For Resins I know many use oven cleaner and bleach white and I believe those are sound materials, I personally don’t use those products. I’ll let others chime in on those.
After the cleaning materials have a chance to work scrub the surface with a tooth brush or vegetable brush. Rinse, Rinse, Rinse and Rinse again! Wipe or let air dry.
If you do not clean the body inside and out before you begin any type of sanding, de-flashing or modifications you have just set yourself up for potential failure of your filler, primer and top coats.
B) Remove all flash and surface imperfections with your favorite tools of choice.
GIVE IT SOME TOOTH
This is the number one reason for all paint failures….. Adhesion! Or lack of it. If you do not have a sound foundation, fillers, primers, and topcoats will likely fail. Have you ever done that super two tone or graphic and went to pull the tape off and the paint came with it…. Lack of adhesion!
I read many posts of I sanded it with 14,0000000 grit paper and I’m having problems, the problem is the surface is way to smooth for the fillers and primers to stick, I would rather see someone error on the side of a courser finish before primer than smoother.
Fillers and Primers have two properties of adhesion one is a chemical bond, Meaning: The chemicals and pigments fuse themselves to the substrate. The other is a mechanical bond, Meaning: The surface is rough enough for the chemicals and pigment can attach themselves to the substrate. Good Chemical Bond and Mechanical Bond equal success of a sound foundation. I would recommend 320 as a final grit before primer. This will maximize both mechanical and chemical bond.
NOTE: In 1:1 preparation most times the substrate is rougher, typically 80-220. Styrene and Resin are too soft of a material to use a grit much courser than 320. I have gone as low as 180 grit; however, a very lite touch is needed here.
I would recommend a final sanding of 320 grit paper followed by a grey scuff pad before primer application for a sound bond.
The three items below can be your best friends….. for those areas with delicate details that you don’t want disturbed house hold cleanser can be used to abrade the surface in those areas.
The product on the right is a commercial grade paste type scuff material. Both of the materials can be applied with a
grey scuff pad or a stiff tooth brush. We use both the cleanser and scuff material on a daily basis on our 1:1 projects.
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These are really nice sanders that you can buy at any big box store. One is the standard size, the other has been cut with a band saw. I cut the standard sizes to various widths.
Sanding media is a hook and loop system with a range of 80, 120, 220 Grits. Great for shaping filler.
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This concludes the first installment of achieving that perfect paint finish!
Next up…… A Primmer on Primer.
Peace…. Jimmy “RASS”
A bit of my personal Eye Candy
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