Proper Paint Prep: Foundational Integrity

Painting and the concluded product can look really glamorous to the youngster just finding started in the paint store. The deep visual appearance of pearlescent shades swimming in high gloss very clear at one particular time was the things of tailor made paint function by cranky, eccentric artists. Now, we consistently see these finishes on authentic devices maker (OEM) cars, and it can in truth be a obstacle to replicate in the mend arena.

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The prepper who simply cannot wait around to paint does effectively to acknowledge that, no matter whether a personalized restoration paint position or a collision fix paint work, the basis should be seem. You can wax or Teflon or ceramic coat for longevity all you want, but if you have developed the paint film on a suspect foundation, you are unable to moderately count on it to “look-great-extensive-time.”

The place It Commences

Exactly where do we commence? As with most factors in the body shop, it is advantageous to start out in the business with the estimate — which actually suggests commencing with instructional education for the estimator.

How can an estimator know that a right restore will need an adjacent panel to be blended — or stripped — prior to refinishing? Decades of working experience will be valuable, as will obtaining the painter support with an audit of the estimate. A paint film mil-gauge will expose a film create previous its proposed thickness. A tiny solvent on a rag rubbed in an inconspicuous location will inform us if the existing coating is reversable (believe lacquer). Paint film builds have limits and have to be stripped when exceeded, and I know of no paint producer who does not recommend eradicating reversible coatings when existing. The point in this article is to detect as a lot as achievable upfront to enable the job to move with no delay.

It is now frequent understanding that every time a supplement is generated for further parts or labor, the job stalls out, and administratively there is a value related with the additional sections processing. We’re receiving pretty excellent at 100% disassembly with a comprehensive elements get in thoughts, but I’d propose we continue to have space for improvement on the paint-labor part of the estimate. I feel each individual paint manufacturer has estimative tutorial methods readily available on its website. Permit us at minimum request to be compensated for what we must do to be certain a proper refinish restore. Now, to the store!

The Human body Shop

We continue on to see sand-scratch signatures from system filler fix that are way too coarse for priming. When a entire body tech claims, “Put a tiny more primer on this,” it can be translated as, “I did not complete this repair service correctly.” Primer is not intended to straighten out wavy filler or to fill deep scratches — it’s built to deliver a ideal layer for painting.

(Remaining) This human body filler edge is obviously not all set for the paint store. Did the body tech blow it off and examine this?
(Middle) The side-gentle approach reveals pinholes and scratches by casting a shadow more than the imperfections.
(Appropriate) Coarse scratches that primer is not created to fill.

Every single paint manufacturer will have tips as to the sandpaper grit that body filler really should be completed in before priming. It is the responsibility of the human body tech to do this complete sanding. The consequence of trying to bury coarse sand scratches with primer is shrinkage — what we call sand-scratch-inflammation. The way the primer alone is used will also lead to this and we’ll go over that later, but let us not child ourselves: The coarsest grit in the paint shop is probable 240 or 220, both equally of which will be adequately loaded by primer. That sand-scratch-swelling is a result of the entire body tech.

Also, the only paint movie a human body filler must be utilized around is unbroken, catalyzed and healed clearcoat — which means it has extremely constrained fill means in that circumstance. Entire body filler generally is intended to be used above bare substrate, necessitating the current paint perform to be ground again earlier the system-fill area. The observe of applying filler about the featheredge started off in the late 1990s or early 2000s, I suppose, when we began to see a thick e-coat from some OEMs that feathered poorly.

The Paint Shop

The first matter we want to do is browse the restore buy (RO). It is not uncommon for the mend to be greater than the clear — so examine the RO.

Clean up

The panels which are to be a component of the repair want to be cleaned. Preferably the automobile has been washed prior to the estimate staying published, but no matter, we’ll get started with a waterborne cleaner to soaked up the panels adopted by toweling off.

Upcoming, we use a solventborne cleaner to wet up the panel and yet again stick to with a toweling. If the car or truck was by now moderately clean, then this will probable suffice. If the car is like most we see, then I’d look at working with a grey scuff pad with each the cleaners in a “dishwashing” motion to scrub the panels clean, towel off, re-damp and towel all over again. It might seem like a large amount of cleansing — which is due to the fact it is — but do it anyway. The waterborne cleaner will get rid of natural contaminates, fowl poop and dirt. The solventborne cleaner will clear away petroleum contaminates, these as highway tar.


My preference is to pick my shade now, considering the fact that every little thing is clean and shiny and less complicated to see a shade that matches. You might use a shade chip from the paint producer, a color camera, your personal spray-out card from a prior restore, a day-distinct components or a mixture of these — it does not issue. Opt for your coloration now.

Be sure to assess the coloration in the pertinent place, either in the blend zone or at the bumper/fender junction if replacing a bumper. If you make your mind up to prep the car or truck in advance of selecting the method you are going to use, then you’ll likely be evaluating the coloration later on in an spot not relevant to the maintenance — preserving in mind that most vehicles have mismatched panels, frequently from the factory. Examine your coloration where by it counts.

Future, we’ll blow the repair service off with compressed air and visually inspect for any pinholes or other discrepancies with the physique filler. Also, experience the entire body work for straightness. Bad physique function, excessive pinholes or ragged, unsanded human body filler edges all have to have to be corrected prior to priming. Use a side-light-weight technique with a flashlight to far better reveal pinholes and scratches.


Listed here we see a textbook physique filler application and a correct featheredge of the paint movie. If I had been coaching the store, I would point out that the quarter panel experienced not been cleaned thoroughly prior to the restore remaining commenced.

Presuming the physique filler has been utilized about bare metal, the paint edge that was ground back desires to be feathered out. A fantastic rule-of-thumb is to sand the featheredge to be an inch vast for each paint job on the panel. If it’s manufacturing unit paint, then it is an inch. If it’s been refinished after, then two inches, and so on till the film-create restrict has been reached and you’re stripping the panel. I like to feather with 220 grit sandpaper. Now, sand the space bordering the featheredge with 320 to 400 (see what your paint rep recommends) in buy to make sure adhesion of the primer.

Thoroughly clean

Soon after sanding, clean up yet again. Waterborne cleaner by itself is preferred right here. Implement and clear every thing, together with the body filler. Blow the area off with compressed air to facilitate a finish evaporation of the cleaner from the filler. Use a paper towel built for waterborne cleaners, lest it break down and depart smaller particulates driving. The reason of this cleansing is to remove all traces of sanding dust.


Mask for prime is an procedure we can get paid for — put it on the mend buy and photograph doc it.

This is now the time to mask-for-key. We can typically get paid to do this, so just take a picture of the masking prior to priming. The objective of masking is to handle the overspray. A person time of failing to do so, resulting in an oversprayed vehicle, must be enough. Guard the car or truck.


The ring of bare metallic between the entire body filler and featheredge likely requirements an etch key. One particular exception is epoxy primer, which is immediate-to-steel (DTM), and etch primer beneath it is a no-no. There are other DTM primers, but generally most effective procedures will dictate an etch under them.

The primer-filler or surfacer is generally used in two to 4 coats with an outdoors-in application. Decades in the past, when we employed lacquer primer, we used it in an inside of-out manner. Not anymore.

Spray your initial coat of primer from stem-to-stern in excess of the fix. Allow for appropriate flash time, generally 5 to 10 minutes. It is significant to enable just about every coat flash off right before making use of more coats. Failing to allow for a appropriate flash will likely add to sand-scratch swelling as the solvents in the primer penetrate the featheredge and become trapped as the thickness of the primer improves and then skins around.

Spray your second coat of primer inside the edges of the very first coat and allow for it to flash. Repeat till concluded. By ready for the suitable flash time, the primer will essentially realize a superior film-make as the first, second and 3rd coats stack on leading of each other somewhat than settling into a single a further.

Block Sanding

If all is as it must be, we’ll have a slight “pitcher’s mound” of primer above the mend. Working with the longest block probable, we now slice the primer flat to the surrounding location. A pair of matters below: 1st, we want a manual coat to expose our sanding development — powdered guideline coat is desired as it exhibits all scratches and remaining pinholes. 2nd, we want to reduce the mound flat, not polish it, so we need to have a grit that will do the work. Some like to use 320 grit paper other people like to use 240. Some even like 220. Use what you will, but maintain in thoughts that these scratches we’re introducing to block sand with will also need to be taken out. If a sealer is to be applied prior to the color, then a last of 400 grit is probably sufficient. If you’re preparing to apply color specifically over the primer, then 600 is possible in which you want to halt. No matter, soon after block sanding, reapply the manual coat and chase out the scratches — you have to generally go away ample materials to sufficiently sand out the sand scratches without developing a minimal place. Do not be the person who sands and sands and sands and it’s nevertheless too reduced.

Mix Panels

No matter whether you’re blending in the panel or blending adjacent panels, the course of action is the same. Making use of a random-orbital DA sander with a soft interface pad and 800 to 1000 grit (see what your paint rep endorses), comprehensively sand the mix space, being mindful not to sand by any edges. Finish up with a grey scuff pad to get the edges and thoroughly clean all sanding dust with waterborne cleaner.

Closing Mask

With anything cleaned, primed and re-cleaned, it’s time to thoroughly blow the car off. My desire is to use a thoroughly clean paper towel and wipe as I blow with compressed air. Now, with the automobile staged in entrance of the booth, get the masking performed to the place exactly where once the car or truck is in the booth, you can pull a plastic bag above it, trim it, final mask it and be spraying in just 10 minutes. Recall, you presently chose a components that matches, and the booth is for painting — not prepping and masking.


If you keep devoted to these fundamentals, then you can fairly steer clear of redos and comebacks, ensuing in a financially rewarding and extended-long lasting, glamorous-display-motor vehicle-finish.

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