Off the gun – Update # 33

Off the gun. A paint finishing technique and a phrase I have heard mentioned many times throughout this project. I have now seen first hand what an ‘off the gun’ finish can look like……and it looks stunning!

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The Rail System

Before the tank could be painted, Steve had to form the new hand and toe rails. He would then have to test fit them to the rows of pedestals that Mark Whiter at Marlin Tooling had manufactured.

 

Steve transported the freshly primed tank home to work on the rail system and tank lids, as well as sand inside and underneath the tank.

 

The pedestals were fitted and the rails were formed to follow the contour of the Heil body.

Steve initially made up some copper tubing for a template of the front of the hand rails where there is a directional change. He then copied the shape onto cardboard and gave this to Tube Bending Ltd in East Tamaki to use as a pattern.

 

Tube Bending required at least 100mm of straight tube past the bend so the hand rail at the front had to be cut and bent as two separate pieces.

To complete the manufacturing of the rail system, Mark Whiter machined some solid stainless steel bullet shaped plugs for each end of the upper and lower rails.

The last job was carried out by Craig Brassey in Half Moon Bay who stainless welded the rail pieces back together and the bullet plugs at each end of the rails.

Our thanks to Mark Whiter, Tube Bending Ltd and Craig Brassey for all their help in recreating the tanker rail system.

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Sanding and Sealing

At the same time that Steve was working on getting the rails formed, Rowan and Nick continued preparing the tank in readiness for painting.

 

They began block sanding the PPG Delfleet CT primer coat using 240 grit paper.

 

After many hours of block sanding, Rowan and Nick finished the paint preparation with 400 grit paper.

The very last job left to do before the tank was delivered to the paint shop was the seam sealing.

 

Rowan did the honours and seam sealed around the checker plate and the half round trim at the bottom edge of the tank.

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The Delivery

As the day approached to deliver the tank to the paint shop, so did some unsettled weather.

We couldn’t afford to have one single drop of rain touch the surface so Steve set about wrapping it to ensure it was fully protected.

 

As luck would have it, we had long time friends, Graham Rollo and Craig Stare, staying with us for the night. Graham and Craig helped Steve to waterproof the tank and it was then parked back inside for the night for delivery the next day.

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Off The Gun

From day one of the restoration, Steve always wanted an ‘off the gun’ finish. This would mean no sanding between colour coats, no clear coat and no buffing and polishing to achieve a high gloss finish.

Instead, the ‘off the gun’ technique is exactly as described. The paint coats are literally sprayed wet on wet and that is it. There is no room for error and no chance of correcting runs or imperfections. It is a type of paint application that has to be perfect in every sense.

In preparation for this update, Rowan and I sat down together a few weeks ago and talked through all the different stages of the paint process. One comment that really got my attention was that Rowan had used a viscosity cup to prepare the PPG paint.  I started researching to see whether a viscosity cup was likely to have been used when the tanker was painted back in 1938. The answer was a definite yes.

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The Viscosity Cup

The viscosity or flow cup is a simple utensil that uses gravity to measure a fluid’s thickness or resistance to flow (technically referred to as viscosity). By timing how long it takes for a set amount of fluid to pass through an opening / orifice in the bottom, you are able to calculate the viscosity of that fluid.

The use of these cups appears to go back to the 1800s although they became a lot more popular after World War 1 when the Ford Motor Co was mass producing the Ford car. One type of flow cup is aptly named the Ford Viscosity Cup and is available with 5 different orifice diameters.

 

The viscosity cup that Rowan used with traces of the red PPG paint.

 

Rowan mixed the PPG Delfleet paint with a PPG hardener and a PPG Delfleet Slow Thinner.

By adjusting the paint with thinners, he achieved the exact consistency he was after with a 17 second flow rate through the viscosity cup.

 

Rowan documented this flow rate, the ambient temperature and the gun set up so as to record the exact settings and mixing of the paint. This will act as a quality control measure for achieving the same paint consistency and results when the cab and front guards / fenders are eventually painted.

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The Painting

 

Steve, Graham and Craig delivered the tank back to Jay at JJ’s Painters Ltd in Pukekohe for the final stretch of this part of the restoration.

 

All the outside surfaces of the tank were masked to avoid any overspray.

 

PPG Delfleet CT primer was applied to all the internal areas and underneath the tank and left for an hour.

 

Two top coats of colour were then sprayed off the gun to all the internal areas.

 

The spats and rear locker doors were sprayed and left to dry in the booth.

 

The tanker was solvent washed to decontaminate the surface and remove any last particles.

The opposite overspray protection was prepared by back masking the interior areas.

Then the moment we had been waiting for since Day 1 finally arrived……

 

Working as a team, Rowan and Jay sprayed two flawless coats of colour off the gun. The end result – beauty and absolute perfection!

Our appreciation and thanks to Jay for the outstanding job and the opportunity to use his booth.

 

Jay and Rowan.

 

The laser straight and high gloss finished tanker reloaded and on the way back home.

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The last of the tanker pieces to be painted were the forward locker doors and the trunk lid.

 

Rowan filled the pitted bezels.

 

The bezels were primed and left to dry.

 

They were then able to be reinstalled in the doors.

 

Rowan committed to paint the last panels on a Friday night and was able to hire a booth at Classic Autobody Panel & Paint Ltd in Pukekohe. Our thanks to Callum Withers for accommodating Rowan and enabling him to complete the last of the tanker panels.

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Arriving At This Point

Many craftsmen, trades people and friends have helped to arrive at this point. We have tried to acknowledge everyone along the way but a big thank you again to all who have been part of the journey so far.

 

The transformation of the tanker from what it was to the beautiful piece it is today is a result of several key factors:

• The clever, determined and talented Simon Tippins and Craig Garland working on the fabrication
• The stunning PPG Delfleet commercial paint system
• The modern, high spec paint booth at JJ’s Painters Ltd
• The professional ‘off the gun’ spraying by Rowan and Jay
• And last but not least, “it’s all in the preparation“. Rowan and Nick have taken the utmost care, have paid such incredible attention to detail and have persistently sought perfection. In the end, the overall finish of the tanker is a credit to their excellent workmanship and testament to Rowan’s quality approach to painting. Our special thanks to them both for their dedication and commitment to see this mammoth task through to the end. Our gratitude also to Rowan for capturing all these photos of the paint process.

As 2021 begins, we hope life can get back to normal as soon as possible for everyone around the globe.

Happy New Year!

Steve & Sue

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References

https://en.wikipedia.org/wiki/Ford_viscosity_cup

https://www.scanz.org.nz/pm/ford-paint-and-lacquer

https://en.wikipedia.org/wiki/Flow_cups

https://www.sciencedirect.com/sdfe/pdf/download/eid/1-s2.0-0300944078800034/first-page-pdf