Tuesday, February 25, 2014

Left Rear Quarter in Primer!

Well, this part of the work on the left rear quarter panel is kind of anticlimactic………and that is actually a GOOD thing.  Generally speaking, priming a body panel is a relatively straight forward process and the success (or failure) of the primer coat is largely determined by the amount of preparation you put into the panel ahead of time. 

As I have documented over the last several weeks, a lot of time and effort has been put into getting the left rear quarter as straight and clean as possible before shooting the panel in epoxy primer/sealer.  As the day approached to finally get the panel in primer, I was checking and re-checking every detail to do as much as I could to ensure success.  And for the most part, success is what I enjoyed.  However, as I have committed to tell the “whole” story on this blog, I did have one relatively minor “oops” that caught me out that required a little extra effort to fix and a second round of primer/sealer to get everything straightened out.
On the first “cut-in” shoot of all of the edges, wheel and window openings, I queued up my small touch-up 3M PPS cup for the job.  This cup is small and very maneuverable in tight places and allows me to get primer in the detail areas quickly and efficiently.

With the cup full and the HVLP turbine spooled up, I started covering the cut-in areas as quickly as I could to conserve primer and avoid excessive film thickness.  If I had been paying better attention at this point, I would have recognized I was going through the primer too fast to be normal and would have avoided a larger problem later.  But, the signs of trouble were subtle enough and I managed to get the cut-in work complete just as I ran out of primer, so the brief window of enlightenment closed as quickly as it opened.
After letting the cut-in work flash off for about an hour, I switched my gun over to the large 3M PPS cup and started mixing up enough primer to coat the entire quarter with a little bit of material to spare to catch any light spots I may have missed.  With everything checked out, I started spraying from the bottom surfaces up, trying to move quickly enough to avoid applying to much material.  Ya…….that’s how it SHOULD have worked anyway.

After getting the full coat of primer on the panel, I noticed again how much material I seemed to be using and how much more overspray I seemed to have (which is very rare when using a turbine HVLP spray system).  As I started quickly inspecting the freshly coated surface, I began to notice very small sags in the primer at almost every spot where the gun had been triggered or where each pass had overlapped.  What the…..?????!!!!
Then I decided to calm down and give this a “think” for a while and start documenting every tiny detail that may have been out of the ordinary.  After all, the primer was already on the surface and the best thing I could do at this point was let it dry fully before I could do anything remedial.  So, with that, I started my review of every detail.

Pretty soon, I was confident that absolutely everything up to the actual process of spraying the first cut-in coat was as perfect as I could make it.  However, the first subtle hint of an issue manifested itself in a slight “catch” in the trigger pull of the spray gun while adjusting the spray pattern.  While an almost imperceptible difference in the gun, this small detail would ultimately prove to be the single item that caused the domino-effect of the whole issue.
The bottom line is that this “catch” was an indicator that the needle was not seating fully into the spray nozzle as a result of debris and paint residue collecting in an almost hidden area of the trigger assembly that is not mentioned in the gun maintenance and cleaning instructions (and YES, I read them!).  The end result was a small amount of material was flowing through the gun all the time, so even when the gun was not triggered, primer was still flowing ever so slightly, and thereby adding thickness to the base coat and causing several small sags and few runs as well when all things flowed out.

So, after sleeping on this discovery overnight, and given the fact that I wanted to let the primer cure fully before going after the goofed spots with the DA, I set about doing a complete teardown, cleaning, lube and reassembly of my trusty spray gun.  This allowed me to revise my maintenance schedule based on these new discoveries to ensure I never have this problem again.
A few days of cure time on the primer had the scene set to start repairing the problem areas with a combination of shaving and sanding with the DA and a small hand block with 80 grit paper.  The rest of the panel was scuffed with medium Scotch Brite pads and everything was cleaned thoroughly with prep solvent and then tacked off in preparation for round 2 of the priming exercise.

In my usual preparatory fashion, I checked off each “pre-flight” detail as I always do with the extra sensitivity to gun condition firmly implanted into the process.  With all boxes checked and the surface freshly masked, cleaned and tacked, I was ready to give it another go.
This time, the gun performance was stunningly improved and the primer laid down very nicely.  In what seemed like only a few minutes, I had the entire quarter finished and was involved in cleaning up the gun.  At this point I started to question just how long and slow this particular problem had been developing?  Had I been working “around” this issue for months and just not noticed the deterioration in performance?  Who knows?  At the end of the day, the left rear quarter looks great and I am moving operations to the right rear quarter for the same treatment.  Hopefully, without the speckle of drama.

Prep work is complete and the bare metal surfaces are cleaned and ready for masking.
The roof was previously primed for protection and this required scuffing with 80-grit paper to prepare it for the primer blending process into the previously primed area.
This is a close-up of the bare metal surface I prefer when applying primer.  Most of this surface is created with 80-grit discs on a DA with light pressure.
All masked up for the first round of priming.......or so I thought!
First step would be priming these "cut-in areas around the window, trunk, door and wheel openings.
Shake, shake, shake..........shake your primer!  It really is the only way and this inexpensive pneumatic shaker is ridiculously handy.  Get one!
Objective evaluation of this shot reveals the first hint of trouble:  that surface is far too gloss and "wet" than it should be and is worse in some spots than others.
After the first coat was completed, I started noticing more little hints that things were not quite right.  In this shot, the primer has flashed about one hour and it still shows some obviously wet areas that should have started to dull by now.  Uh oh...
Out comes my inspection light and my worst fears are confirmed.  Patches of slight to moderate sagging are evident on several areas of the quarter.  *Insert long string of colorful expletives here!*
Careful investigation would reveal a very subtle spray gun fault that was responsible for the entire issue.  Yep......fixed that.
Even after a few days of cure time, the panel remains too glossy for a "normal" primer application.  I have my work cut out for me, but a few days of careful shaving and sanding of the problem areas and a complete tune-up of my spray gun and we were ready to give it a proper go.

This image shows a much more agreeable coat of primer.  Not nearly as glossy and heavy looking as on the first round and it's laying very flat and smooth.
From another angle, the finish is clearly superior to the first attempt.  Funny how things go when your equipment is up to par!

After the masking was pulled following only a hour of flash time, the surface look great and is noticeably smoother than before.  We got this!

Friday, February 14, 2014

Smoothing Up the Left Rear Quarter

At last, the Night Mission project has reached a point where actual formal bodywork can begin!  In my last update, the left rear quarter metal work was completed and preparations were being made to begin the careful process of applying fillers and leveling all of the repaired areas. 
In most “collision” repair shops, the filling process is often a single step process before primer and paint.  Most of what drives this technique is pure profitability in a cut-throat and murderously competitive market where insurance claims dominate the landscape and any technique to shorten the turnover rate equals serious dollars on the bottom line.

The obvious down side to this is that repairs are rarely of the quality that is expected at the level “we” are looking for, and the incentive to “cave-it-and-pave-it” gets higher as the day and project progresses.  This is why I maintain my personal philosophy that shops doing everyday collision work (a.k.a. “body shops”), do not make good places to take your restoration work to.  It is an entirely different mindset.
In my shop, I hold filling a panel as essentially a three step process:  1) “Heavy” filler work which involves conventional poly filler like All-Metal and Rage, 2) “Light” filler work which centers around glazing putty with very thin applications, and finally 3) “Finish” filler work which is exclusively a sprayable, high-build filler over the entire panel that will be blocked to the perfect finish before primer/sealer application and paint.  This is obviously only a fraction of the true work involved in getting a panel flat and laser straight, but as the specifics of applying fillers goes, that is the process I follow and will document here.

On the heels of the last update where the metal work was completed and all remaining surface repairs were made, it was finally time to begin the “heavy” filler work on the quarter.  I should point out that when I use the term “heavy”, I am only referring to the density of the filler used first and NOT the amount of filler applied.  Remember, this ain’t no “body shop”.
There is a lot of opinion swirling around about whether or not to apply filler to bare metal or over an epoxy primer as a best practice.  I am of the opinion that “heavy” fillers should be applied to properly prepared bare metal surfaces for maximum adhesion.  My main reason for this is that I prefer to use a fairly aggressive sanding grit to prepare the bare metal surface that simply cannot be supported by any epoxy primer.  I like to use a DA sander with 36 grit paper to lightly scuff the bare metal surfaces in a non-directional pattern to give the fillers plenty of “tooth” to grip and hold on to.  Once the heavy filling work is complete, I seal the entire panel with epoxy and apply subsequent filling work over the primed surface after sanding with 80 grit.  This is plenty of tooth for the lighter glazing fillers and sprayable poly fillers to bond to without concern for finish integrity.  Following that, the sanding prep before the final primer/sealer coats is straight out of the preparation recommendations of the primer manufacturer and rarely gets more aggressive than 150 grit to ensure sanding marks do not surface in the upper finishing coats.

As described above, I prepared the bare metal surfaces with a light application of 36 grit paper on my DA sander, followed by a thorough washing of the surface with acetone to remove any remaining traces of marking ink or machinist dye.  Then I followed up with a thorough swabbing of the panel with commercial wax and grease remover and let everything dry thoroughly.
The first order of business is to apply a “base” filler over the areas where welds and/or heat has been applied to the panel.  I prefer to use a metalized filler called All-Metal as a base filler over these particular areas as it is extremely durable and strong and seals the welded areas extremely well.  The down side is that this material is designed to replace lead filler and this makes it much tougher to sand and shape, so I use it sparingly and NEVER as a final finish coat.

In similar fashion to the bare metal work described in my last post, I use a guide coat to act as my road map to sanding each and every coat of filler that is applied.  I prefer a graphite powdered guide coat by 3M that goes on very smooth and does an excellent job coating the entire surface of the filler evenly.  It doesn’t load the sand paper at all and is as easy to apply as wiping steam off a bathroom mirror.  It is pretty much the state of the art in guide coats and is far more economical that the old rattle can guide coat sprays of the past.
Once the All Metal filler completely covers the welded or heated areas and has been dressed down with 80 grit paper by hand below final surface, I move to my favorite “heavy” body filler called Rage Gold by Evercoat.  I have been using Rage for over 20 years and the stuff continues to perform extremely well.  Every improvement to the formula has been excellent and it has outstanding workability and sanding characteristics.  The one “trick” I employ is to shake Rage thoroughly in my pneumatic shaker rather than stirring it before use.  This removes 99% of the air bubbles in the product and gives it a buttery smooth texture that is very easy to mix and apply with virtually no pinholes.

At this point, you must condition yourself to the idea that filer work is an iterative process.  In other words, any repair area will receive several thin coats of filler, followed by DA and hand sanding between each coat until the surface is exactly as you want it.  Applying a heavy coat of filler will only create more work for you in the long run and exhaust and frustrate you during the hand blocking process.  This is an exercise in patience and discipline and it is worth taking your time to apply and finish correctly.  Since most of the filler will end up on the ground, wasting it by applying too much of it is just costing you money that could be better spent on other things.
Since I was fortunate in being able to bring the base metal very close to final shape, none of the areas I needed to fill would require very much material to get where it needed to be.  However, even the thinnest filled sections required at least 2 thin applications of filler to get the surface I was looking for.  Most areas will regularly see 4 to 6 applications depending on the amount of filler required and the complexity of the repair surface.  That is simply what it takes to get the surfaces to shape up the way they are intended without tremendous waste.

As the filler surfaces approach their final desired finish, I try to purposely slow down in my block sanding to ensure I don’t over do it.  Also, I prefer to use the longest sanding blocks possible for the area that I am working to help distribute the sanding load over the largest surface area to reduce the likelihood of plowing an edge or gouging an otherwise finished surface.
I try to discipline myself to always wear nitrile examination gloves while I sand and check the surface.  Most obviously, a glove keep the oils from my hands off the surfaces as much as possible and the thin membrane of nitrile rubber actually increases the sensitivity in the fingers, allowing very tiny irregularities to be felt in the surface that cannot be seen with the eye.

After a several days dedicated to the filling and blocking process, I had the left rear quarter panel in pretty good shape and ready to begin the prep work to get it in a thin coat of epoxy primer/sealer before moving on to the right side quarter and tail light panel.  This coat of epoxy will be the first real opportunity to see how the surfaces are shaping up and will give a hint on where the lighter filler work will be required.  Yep……we’ll be back here again before it’s over!

I prefer to cover any areas that have been welded or have heat applied as part of metal work with All-Metal filler to seal the area and provide a strong base.  I use this metalized filler sparingly as it is much more difficult to sand and shape than conventional filler.  This is a very thin skim coat, the bulk of which will be sanded away.
After sanding with a DA and blocking by hand, the All-Metal filler is in place and this area is ready for a follow-up skim of Rage Gold polyester filler to bring up the surface to the perfect finish.

One of the more heavily welded areas was this section of the quarter at the rocker joint.  I welded this seam up and smoothed it for aesthetic reasons and this is the first coat of All-Metal.

With most of the first coat of All-Metal sanded away, I use a pencil to mark the areas that will require additional filler on the subsequent coats.  Once the entire weld seam is sealed with All-Metal, I move on to Rage Gold to finish the "heavy" filler work in this area.
My favorite way to prepare Rage Gold filler for use is to shake it in my pneumatic paint shaker for 3-4 minutes.  This does an excellent job of removing air bubbles and smoothing the mixture to a perfect consistency for ease of application.  I just scoop out the desired amount, add hardener and mix it well for about a minute and go to work.  Life is not complete without a paint shaker!

While this looks like a lot of filler at first glance, it is actually a thin coat over a large area extending well beyond the actual repair areas.  This allows efficient filling of the repair while allowing blocking with the longest blocks that can be used in each area.  This makes for a much more consistent finish in shorter time than applying heavy layers and having to carve off massive amounts of cured filler before you ever get near the desired shape.

Once the Rage Gold filler "gels up", I use a Surform (a.k.a. cheese grater) file tool to shave the filler into it's rough shape.  Once this is done, the filler is left to cure fully before block sanding begins.

Here is the same area after the second coat of Rage has been blocked.  Plenty left to do, but the idea is to sneak up on the surface you want.

A third and fourth application were required before I felt the surface was where it needed to be.
A fifth and sixth filling iteration was required in the area of the lower front fender opening to get the contour just right.  After this was blocked by hand, it was time to move on to the next repair area further back on the quarter.

Very, very thin coats of filler were used in the center of the panel to get these very slight irregularities corrected.  It looks a bit daunting, but all but one of these areas was invisible to the eye and were only revealed using 3M dry guide coat as an indicator of the surface along with a hand gloved with a nitrile examination glove.  This guide coat coupled with the amplified tactile sensitivity offered by the thin nitrile glove allowed me to feel irregularities that could not be easily seen (if at all).

Here is an area that is often overlooked in custom and restored cars:  The fender lip reveal.  I take extra care to make this lip reveal even all the way around the wheel opening and to smooth it up so it blends smoothly into the fender.  It's a small detail that makes a difference people will notice subconsciously.

With All-Metal filler already applied to the roof seam, this area will be smoothed up with Rage Gold until this critical contour on the Boss is seamless and perfect before paint.

My car was originally fitted with rear window louvers.  However, they were stolen off the car in about 1977 and the damaged latch holes were all that was left.  I don't care for these louvers and long ago decided to leave them out of this build.  With that, I welded up the holes and now it has come time to apply a skim of filler over the repair area which can be seen about 1/3 of the way across the bottom of the window opening (in the middle of the sanded bare metal area).  At the same time, I will be filling the outer panel seam that was previously welded and smoothed, again for aesthetic reasons.

There you have it.  Though it doesn't look like much, the left rear quarter is now ready for primer/sealer and at least two more passes of filling and smoothing work yet to come.  Like I said before:  This ain't no body shop job.......

At this angle, you can better see the detail in the roof seam that is now much smoother than it was before the "heavy" filling process was complete.  You can also get an idea of just how little filling was required overall across the entire quarter.  No bad after 44 years of abuse and neglect.

Monday, February 10, 2014

Dent Repair & Metal Finishing on Left Rear Quarter

With the snowiest winter in decades demanding more time than it deserves (thank the Lord for a new snow blower!), a week of time spent out of the country for work, and a shop heater misbehaving, I was getting a bit anxious to spend proper time in the shop dedicated to the Boss since my last update.  However, though I have been delinquent in keeping up with fresh entries for a few weeks, I have managed to make good progress.

To begin, the task of repairing 44 years’ worth of accumulated dents and dings in the left rear quarter had finally come on the menu.  Having managed to clean and preserve the bare metal panel successfully, the time to sit down to the careful and particularly delicate work of dent removal and metal finishing was at hand.

After several hours of careful study of every inch of the panel, I decided it best to start at the front and top half of the quarter and methodically work my way to the back, repairing every irregularity in a given area before moving on to the front lower half and repeating the process.  This method allowed me to maintain a clear focus on each repair area until the repairs were as good as I could possibly make them.
Beginning in the area just behind the striker post, I had a nice, sharp dent that slightly deformed the leading edge and radiated back into the open panel by several inches.  Like with any proper metal work, some form of “indicator” is required to understand and visualize the extent of the damaged area so you know exactly what needs to be repaired and how far out from the heaviest damage to begin the correction.  The first rule of dent removal is to understand that dents must be removed in the reverse order in which they were created.  In other words, the outer peripheral damage must be slowly moved back into shape first if you are to get the “core” damage to move as well.  In simplest terms, if the dent started at the front and ended at the back, the repair of that dent starts at the back and moves to the front.

My preferred “indicator” on bare metal is a giant Sharpie marker instead of conventional guide coat paint.  It dries quicker, is much thinner, very easy to clean up and does a nice job of highlighting the low spots.  Oh, and it’s ridiculously cheap too!  So, the first order of business is to swab the entire repair area with Sharpie and lightly scuff the surface with a rigid sanding block with 80 grit paper.  Very quickly, the true extent of the dent is revealed and the road map for repair is defined.
Starting at the outer edge of the dent, began the repair by welding a series of draw pins about ½” inboard of the edge of the dent and began the careful process of pulling the metal while gently tapping the outer crown with a dinging spoon.  Then I cut the pins off and ground the heads smooth and inked the area.  After the ink dried, I lightly sanded the surface again with the rigid sanding block to check progress and define what area would need attention next.  This basic process was iterated about a dozen times over several hours to bring the surface as close to the original contour as possible.  Once complete, all that remained were two small shallow points where I had to shrink the metal with heat to pull the leading edge back into form and a few shadow outlines where the welded draw pins were removed.  All told, the final skim of filler that would be required will be less that about .020”.

Moving back on the quarter to the trailing fender lip radius, I had to attend to a dent that was an alarmingly similar to the first one.  Fortunately, the damage was not as severe or deep, so less time was required to get the metal to return to its original position.  Using the same technique as previously described, this dent was pulled and the fender lip radius restored such that almost no filler will be required at all.
The final metal finishing task on this quarter panel involved straightening up the area where the marker light was filled with a welded patch as an aesthetic improvement.  Since this would involve a much larger area that would require attention, I marked out the zone with a marker to help keep my mind focused on the specific repair area.  Then I coated the area with machinist dye as an indicator similar to the Sharpie marker I used earlier.  Machinist dye is easier to apply over a large area than Shaprie marker, so I use it for the sake of convenience.  Another advantage to it is that it stays wet longer and allows you to look at the panel from various angles with a high gloss on the surface to see in great detail very subtle (and not-so-subtle) irregularities in the metal that will require attention.

Again, the repair area was sanded to provide the appropriate contrast and I went to work with more conventional hammers and dollies, dinging spoons, bulls eye picks, a large shrinking disc and rubber mallets to nudge the surfaces as close as possible to the original contour.  No welded draw pins were required in this critical area.  Unfortunately, I failed to properly document this operation but I am happy to report that this are too will require very little filler to get straight.
The final area of concern was the front lower joint between the quarter and the rocker.  This area required extensive repair for rust and other damage and I welded the seam and ground it smooth for aesthetics.  Careful metal work during the reconstructive phase allowed that no heavy dent repair was required in this area as the areas that I wanted to be low (e.g. weld seams) were already in shape and the rest of the contours were very close to what they were originally.  So after a few minutes with a dinging spoon and dolly, the area was ready for filler.

With that, the “heavy” metal work on the left rear quarter was complete and it was time to plan the process of applying fillers and smoothing up the panel and the associated seams before sealing everything up with primer.

Using a huge Sharpie marker, I coat the entire damaged area and use it as a guide coat to see just where I need to work.  The camera flash already makes the dent very obvious.

Lightly sanding over the inked area very clearly shows the extent of the repair area.  As you can see in this shot, the low spot carries out into the panel quite a bit farther than can be detected with the naked eye.  However, with this technique, our work area is cleanly defined.

Beginning about 1/2" from the outer edge of the dent, I weld draw pins to the surface and begin the gentle pull-and-tap technique to ease the metal back into its original shape.  This is an iterative process that requires patience and a clear understanding that the dent must be removed in the reverse order that it was created.  In this case, the initial impact point is at the far left edge of the dent.  That is why the repair is started from the far right side as it was the "last" area to be damaged in this singular impact.

After about three hours and 32 draw pins later, the metal is almost perfectly returned to it's original form.  The two dark spots on the left edge are the result of some very localized heat-shrinking I needed to do to get the door opening edge to come back to shape.  This was done with a special tip on the stud welder gun that pinpoints the heat in a very small area and minimizes distortion in the material.  These small marks are actually very shallow, but filled with ink, so they look very pronounced in the shot.

A handful of draw pins and one less dent!

Even sky lighting the repair area shows very little filler will be required to get this area perfectly smooth.  Now to repeat this repair procedure for all of the other areas on this quarter!

My photo-documentation skills really suffered on this blog update, but the sanded area in this shot was once the location of another nasty little dent that deformed the wheel arch.  Using the identical techniques described above to remove the first dent, this area will require virtually no filler as well.

A larger and more challenging area to straighten is the rear quarter section where the original marker light hole was welded up.  To enable me to more clearly focus on the area, I outline the full extent of the work surface with a marker as seen here.

Since the repair area is much larger, I use sprayable machinist dye to coat the surface as my guide coat.  While it is wet and glossy, I can easily spot areas that will need work.  This is something I do quite regularly and often use simple wax and grease remover sprayed on the panel to check my progress and visualize the surface in final finish.  Works great!
After several hours of very gentle manipulation from both sides of the panel, the marker light area is quite straight and ready for filler.
The last area I needed to evaluate was the lower front joint area where the quarter and rocker join.  I welded this seam up for aesthetic purposes and repairs were required to the rocker and wheel arch area as part of the rust repair procedures.  Fortunately, the repair techniques I used allowed the welds to be slightly below the original surfaces and only slight correction to the surfaces were required before moving on.