Crack Re-Repair and Paint Performance

A week or so ago, I reported that I had discovered repair failures in the seat riser cracks.

I also indicated that I had a couple of different choices in dealing with the failed repairs - either "veneer" the entire panel, or just suffer the presence of the cracks.  I was dangerously close to accepting the latter choice.

These are about the only choices offered by the last known (to me) carriage restoration book, published in the 1990s.

Fortunately I have a couple of friends that won't let me settle for second best.

Walt and Kathy Ashford, dedicated carriage enthusiasts, called to discuss the method that Walt prefers in dealing with panel cracks.

First off, I'll talk about the mistake I made in repairing the cracks.  I did everything right, but I selected the wrong material for the repair.  I was in the midst of a honeymoon with a newly discovered product, a marine epoxy fairing compound.  Sort of like a sea-going Bondo, as it turns out.  I really can't explain this choice except for the fact that the cracks seemed so shallow after glue seeped up into the voids, that I thought I could get away with a cosmetic, as opposed to a structural repair.

The fairing compound is for filling voids.  It is NOT, as it turns out, designed for holding together two edges of wood that are likely to move with changes in temperature and humidity.

I had backed the cracks with strong glue and strips of oak, which probably helped to keep things from getting worse than they did.  However, there were places where I could not support the cracks from behind, notably, around the seat pillars.  The evidence suggests that this is where the movement really began.  In the photo above, I'm pointing to another area of a crack which I was unable to back with a piece of oak...the crack was directly below the seat frame.

One of the problems with backing a split with a glued reinforcement is that you can't do it in places where the backing piece will show, such as on a sleigh dash, or an open cart, where both sides of the wood are visible.

Walt and Kathy called to discuss their technique for repairing panel cracks, and as it turns out, I should have been smart enough to figure it out for myself.  I just simply didn't think the wood would move again after gluing the backing pieces on.

Walt's preference for repair material is WEST System Epoxy Resin.  Please note that I am not sure if this is the EXACT product that Walt uses (hoping he'll correct me if not) but it is the brand he mentioned.  The structural epoxies that I have used with great success  come from Abatron.

These products are NOT your grandfather's polyester fiberglass resin!  They are formulated to creep...and creep...and creep...into wood fibers, rotten wood and voids and they form a phenomenally strong bond.

Walt first asked me if I had used wood sealer before priming.  The answer was "yes," but only one coat.  That is what the label calls for.  Experience trumps labels though, and Walt advised that I'd have been better off to apply three or so coats.  Particularly since the body spent so much time in storage, and had to endure some serious changes in temperature and humidity.  Primers are porous and offer very little protection to old, fragile wood panels.   Unfortunately, favorable weather for properly curing repair materials and painting, lasts only a very brief time in our region, and not everything can get done in a timely fashion when one is working in a metal shed.

(As an important note, NONE of the Abatron repairs to the seat or body have failed in a year's time, either painted or not.)

Walt "dams up" any potential places that the resin can leak out of the repair zone.  His preference is for automotive masking tape.  All I had on hand was painter's masking tape.  He ensures that the repair is made on a warm, dry (not humid) day, and even takes the precaution of warming the wood and resin, to maximize saturation. (I discovered that warming the resin too much shortens its pot life drastically - had to start over!) I worked in the sun on an 85 degree day, allowing the materials to warm for an hour or so before I began.

I masked off the areas adjacent to the repairs, because I know this stuff gets all over EVERYTHING.  It is SO slippery.  I used a 3ml livestock syringe to drip resin into the cracks but I couldn't keep a needle on the end of the syringe.  It kept sliding off.

Now the fun begins.  You need to be able to babysit the project ALL DAY.  If there is the tiniest bit of fluidity to the resin, it will continue to creep into voids.  And it will find voids to creep into ALL DAY.

Walt advised me to use a .004" feeler gauge to work air pockets out of the crack.  That was a really great idea as several bubbles worked up to the surface.

I kept dribbling in resin until it domed up over the crack and stayed that way.  In the morning, it appeared that over night, a little more resin had crept into the voids.

Once the resin cured completely, I sanded the excess away, down to the original repair.  Now, here's my big concern.  The cracks are still contaminated with the previous repair materials.

Had I tried to pry out the fairing compound I would have had a mess of epic proportions on my hand.  A hairline crack in the paint, should it reopen, is just not worth that much to me.  But if the crack fails again, it won't be the Abatron that fails, it will be the fairing compound. Presently, there are NO VOIDS in the area of the repair.  And the repairs will be covered with enamel before another major weather change occurs.  If it happens to hit 100 degrees and 12% humidity again before the final painting, the body will come into the house!

To finish up, I smeared some automotive spot putty over the repair to fill pinholes, etc., then sanded it all smooth again.

Reprimed and drying, awaiting a light sanding before going into the paint booth.

BUT WAIT, there's more...







PAINT PERFORMANCE  

 After one more Karate Kid style procedure - spray on, wipe off - I got a nice coat of black paint on the long-suffering seat.

Except...

The demon Orange Peel reared its ugly head to plague me again.

All throughout my last project, I battled orange peel, usually losing.  I did everything to optimize painting that I could think of, and doggone it!  I haven't had ONE SPECK of orange peel in the yellow paint!  What could be different?

Well...

I mixed the yellow paint myself.  The yellow paint was alkyd enamel.  The two cans of white paint were urethane enamel.

My last project was all alkyd enamel.  The black paint on the seat is straight alkyd enamel.

Umm....connection here? 

I don't know.  I have some research to do.  Tomorrow I'm putting in an order for the urethane enamel in black. While I'm waiting for it, the running gear will go into the paint booth, and I still have two wheels to sand and paint.  The carriage body can rest for awhile longer and it will be the "guinea pig" for the urethane paint.

My sincerest thanks to Walt and Kathy for keeping me propped up on this project when the going gets rough, and for sharing their tips on successful repair techniques!