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Surface Prep 101 / The Dynamic Duo


jwrass

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A large percentage of paint failures stem from the lack of or poor surface preparation of the substrate. Be it your Model, House or the cats tail if the surface is not clean, scuffed or sanded The potential rate for failure is great.

Two of the procedures that are often over looked or done poorly are cleanliness and giving the substrate a tooth for your primers and top coats.

Cleanliness: The first step in preparing the surface is it a good bath in soap and water. Be careful here, not all soaps are equal. Most soaps contain a scent or perfume, Some of these agents come from the make up sector and contain animal fat. Fat equals grease, grease equals fish eyes or a surface that has a film that acts as a barrier that prevents a true clean surface.

The Gold standard of the 1:1 custom paint arena is IVORY original scent dish soap. This is a great product for your first washing and as a lubricant for wet sanding. A few drops in a bucket will help soften your wet/dry paper and will act as a lubricant for easier sanding and aids in paper clogging.

Tooth: For any primer or paint to stick to a substrate you need to create a mechanical bond, that process would be through sanding and scuffing the surface to create that tooth for the mechanical bond. A great aid in getting the surface scuffed and dulled to receive the primer and or top coat is Comet Cleanser and or Soft Scrub. After sanding and scuffing follow up with a mixture of water and cleanser to a consistency a little thinner than tooth paste, apply this with a medium bristle tooth brush. You can be fairly aggressive when brushing with this paste. When you are finished with this step wash the subject to remove all residue and dry. All surfaces should be dull (no shiny spots) if you have any areas that are not dull go back and work those area's until they are dull

There are many professional products in the 1:1 market that we use on a regular basis and they are part of our arsenal at the shop, We use products by the SEM company, they are SEM Soap and SEM Scuff & Clean, However you will  spend more than a few dollars for these professional products (fairly expensive) For a few dollars you can get the same results with household products. I used this method for years, I purchase the SEM products as a convenience and to maintain consistency within our group, a everyone on the same page scenario.

EDIT 1/18/16: Like Tom, I often let parts air dry, However I do a final wipe right before I paint with a micro fiber towel dampened with the Iso/water solution.

Like Ace, I use paper towel as well....... They have to be pure white, Non Scented and No Ink. both of these will contaminate the surface

I use a tack cloth before all applications of primer and paint also between coats

I have been using this method or a variation of it for some 40 years and have not had a paint failure due to poor adhesion. Give it a try.......... My Motto: Always use best practices!

Respectfully Submitted,

Jimmy "RASS"

IMG_0787.JPG

Edited by jwrass
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Good tips. I started using and recommending Comet somewhere around 2012, and it works great.

Like Jimmy says, you can be aggressive with the stuff without worrying about fubarring details. Sandpaper, on the other hand, will tend to soften and dull details, and it just can NOT get in all the little nooks and crannies next to chrome trim, door-handles, etc.

I've found a hot-water rinse is all that's needed to get all the Comet and residue off the model. I personally prefer to use el-cheapo recycled white paper towels, the grocery store generic brand, to mop up whatever water remains on the model.

Then, I've come to rely on a thorough wipe-down with clean paper towels and 70% isopropyl alcohol. It's the best wax-and-grease (and silicone too!!) remover I've ever found, and I use it on full-size custom and aircraft paint jobs where I simply can't afford a redo because of fisheyes. The stuff works.

Edited by Ace-Garageguy
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I was going to do a follow up on post...............Ace is spot on with the isopropyl / water mix. (iso/water by % Vol ) My ratio is a bit different than Aces due to the nature of the work I do, his is a great ratio for a overall pre paint wash! Not only is it a great wax, grease, silicone remover. It kills the static charge that builds up when you rub plastic and a rag together when prepping that body for that ultimate clean paint job. You just set yourself up for failure if you didn't kill the static, The charge will actually pull dirt into your body. I have actually used static to my advantage on helmets and snowmobile cowling anything of plastic type nature. The static charge will actually pull every bit of paint from a fully loaded Pinstriping or Lettering brush with a incredible random pattern. If static charge has that much ability to pull heavy bodies paint from a brush how much dust to you think that highly charged body is attracting???. Kill the static before you paint and you will be amazed at how clean your paint work will be! Peace..............jimmy "RASS"

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Good information - good to have the details about the specific products to use - absolutely, preparation is the key to good results - Thank you for adding knowledge to the toolbox

I haven't painted anything in a while but have a couple of thing prepped. I used 3M 07745 Scotch-Brite.  It is gold, finer abrasive than the gray, and is for 1:1 automotive intercoat or clear coat prep.  It puts some tooth on the plastic without causing damage to the emblems.  It also gets into the finer details. --- your thoughts?

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I used 3M 07745 Scotch-Brite.  It is gold, finer abrasive than the gray, and is for 1:1 automotive intercoat or clear coat prep.  It puts some tooth on the plastic without causing damage to the emblems.  It also gets into the finer details. --- your thoughts?

I've used it in the past, and it works better than sandpaper. However, once I thought of the Comet deal and tried it, I'll never go back. I've looked at surfaces prepared using both methods under magnification, and the Comet is superior in my judgement...but don't take my word for it.

Actually, I started using Comet because I was stripping a lot of gluebombs with EasyOff oven cleaner, and I needed something that would scrub the sometimes soapy residue it left behind. Comet did the job, and I reasoned it would probably remove mold-lubricant contaminants from virgin kit parts as well. The alcohol was insurance....and a carry-over from techniques I use painting real aircraft. Few things will ruin your day like getting a 20-foot streak of fisheyes down the side of a fuselage.  B)

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Fisheyes can be a royal pain. We custom color firearms using Dura Coat colors. We had a Glock that was about 20 years old that the new owner wanted colored. We did our standard cleaning with carb cleaner to remove all of the oils and lubricants  commonly found on guns. Hit it with the paint, and instant fisheyes everywhere. Went through the same routine only more concentrated three times. No joy. Just before giving up in disgust, we got hold of the previous owner of the gun to see what he may have used on it. He told us he soaked the polymer frame in ArmorAll to make it look newer before he sold it to the present owner. Ah HAAA! So we boiled the frame out in first a water/Comet solution and then plain water to get it clean. Turned out OK after that. Had some hydraulic contaminents on the belly of an MD500 chopper belonging to my old boss as well that gave me fits. May not be able to see what is about to give you fits, but if you EXPECT that it is there and prepare as if it IS there, you can do no better.

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Good stuff.  I wasn't aware of the static charge thing but I believe it just ruined my first coat on my Dart. I'll be trying your alky/water mix.  Thanks.

Dennis..........Bummer hopefully you saved it before you put it in the pond.... I do alot of artwork with various mediums that are always on the fresh side. If you were able to save the paint without the pond. Mix your iso/water at a ratio of 20% iso to 80% water with some mediums a strong solution of iso may harm the surface. Let us know how this works for you! Good Luck!

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Fisheyes can be a royal pain. We custom color firearms using Dura Coat colors. We had a Glock that was about 20 years old that the new owner wanted colored. We did our standard cleaning with carb cleaner to remove all of the oils and lubricants  commonly found on guns. Hit it with the paint, and instant fisheyes everywhere. Went through the same routine only more concentrated three times. No joy. Just before giving up in disgust, we got hold of the previous owner of the gun to see what he may have used on it. He told us he soaked the polymer frame in ArmorAll to make it look newer before he sold it to the present owner. Ah HAAA! So we boiled the frame out in first a water/Comet solution and then plain water to get it clean. Turned out OK after that. Had some hydraulic contaminents on the belly of an MD500 chopper belonging to my old boss as well that gave me fits. May not be able to see what is about to give you fits, but if you EXPECT that it is there and prepare as if it IS there, you can do no better.

Tom.........Any mention or site of Armor-All or anything with silicone in it makes me shutter.......... You will never see any sight of those products in my shop............Honesty..........you don't want to know!

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My experience with cleanser comes strictly from the 1:1 world that transferred over to model building. I too think it is one of the best products to scuff plastic or any painted surface for that matter to get some tooth.

Does anyone remember polishing your models with tooth paste before the Government deemed some tooth paste was to abrasive for teeth?

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My experience with cleanser comes strictly from the 1:1 world that transferred over to model building. I too think it is one of the best products to scuff plastic or any painted surface for that matter to get some tooth.

Does anyone remember polishing your models with tooth paste before the Government deemed some tooth paste was to abrasive for teeth?

I used toothpaste when I was a kid to try to get some gloss on old Testors enamel. I had tried my father's DuPont rubbing compound, and it cut down to the plastic in no time at all. :lol:

Speaking of fisheyes and silicone and Armor All...Long ago I worked in a shop that had an old-school booth with the filters in the doors (open to outside). I was shooting the last coat of clear on a '36 Bentley and the whole entire coat exploded in fisheyes. Turns out our new idiot kid had pulled a car for delivery right in front of the doors / filters, and started spraying Armor All on the tires and interior.

Fans sucked it right through the filters. Took a LOT of effort to fix it...and of course I had to fix it for free.

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I used toothpaste when I was a kid to try to get some gloss on old Testors enamel. I had tried my father's DuPont rubbing compound, and it cut down to the plastic in no time at all. :lol:

Speaking of fisheyes and silicone and Armor All...Long ago I worked in a shop that had an old-school booth with the filters in the doors (open to outside). I was shooting the last coat of clear on a '36 Bentley and the whole entire coat exploded in fisheyes. Turns out our new idiot kid had pulled a car for delivery right in front of the doors / filters, and started spraying Armor All on the tires and interior.

Fans sucked it right through the filters. Took a LOT of effort to fix it...and of course I had to fix it for free.

Hey Bill, Tooth Paste and models....... We are showing our age!

My honestly you don't want to know story... I did a crotch rocket Pearl White paneled graphics Himsil/Jefferires fades ready for clear. Sprayed the rails of the overhead door with garage door lube, used a straw and buffered it with a rag. Stuff is like drywall dust... Couldn't save it, I got in some extra special practice and a lighter wallet

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Bill, thanks for the feedback on the Scotch-brite -

I did the Scotch-brite prep on one of Revell's new NASCAR Fusions - they are made of some very tough play ready plastic - kicked my butt.  It will be good experience to go over it again with cleanser to see how it comes out.

Guys, thanks again for the information and the stories - no ArmorAll or WD-40 here

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Dennis..........Bummer hopefully you saved it before you put it in the pond.... I do alot of artwork with various mediums that are always on the fresh side. If you were able to save the paint without the pond. Mix your iso/water at a ratio of 20% iso to 80% water with some mediums a strong solution of iso may harm the surface. Let us know how this works for you! Good Luck!

Thanks James.  I haven't stripped it and don't think I have to because it was only the light first coat.  I plan to do work on it this weekend.  I'll keep you up to date.

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  • 5 months later...

My experience with cleanser comes strictly from the 1:1 world that transferred over to model building. I too think it is one of the best products to scuff plastic or any painted surface for that matter to get some tooth.

Does anyone remember polishing your models with tooth paste before the Government deemed some tooth paste was to abrasive for teeth?

Good thread! I use original Crest on bare plastic with good results, will be giving Comet a try.

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  • 3 weeks later...

I'll toss my hat in on the Comet / Ajax cleanser on full size and model paint jobs.   The trick to testing cleanliness used to be water beading on the just cleaned surface, I still use it to this day.  After cleaning and testing, the bodywork is blown dry with filtered compressed air so I'm not putting any oil or moisture back on the bodywork.  The next time I touch the bodywork my hands are covered with nitrile gloves which I wear up until the paintwork is laid down.  

We used to use a trick (still do) when doing pinstriping or custom paint work over fiberglass and plastic body panels to kill the static by spraying the back of the panel with a spray bottle of plain old tap water, worked every time!  I've read where Ed Roth used to spit on the car in the area he was striping to kill the static; always wondered what the look on his customer's face was after Ed spit on their pride and joy!

I used to polish model paint jobs with Crest and then Pearl Drops when I was a kid too, worked really well.  That might be why a lot of us seasoned guys have more than our share of caps on our teeth!!  (Still got'em!!). I remember if you weren't careful you could burn right through two coats of Testers enamel pretty quick!!

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thank you! i have searched her a few times and could not see anything about cleaning a model. i must have just been lucky so far cause im not gonna lie i have not cleaned a model yet..i just try not to handle them very much and havent had any issues with paint yet. but i know my time is coming so washing them will be happening from now on. 

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