Behind the Scenes: Conserving Vehicles

Author: Josh Seymour, Conservation Intern

I undertook some general conservation treatment on a vehicle displayed in the museum. The vehicle is an International Half-Track M5. Introduced to service in 1943 and modified for REME use, modifications include a crane and winch attached to the front, with a heightened roof at the rear.

A vehicle with both wheels and tracks and a crane on the front, situated inside a large hangar with other displays around it.

Half-Track M5 with vacuum.

As a conservator, my job was to assess what work was required. Below are the problems I found, my solutions, and advice for anyone undertaking a similar project.

General Cleaning

A lot of dust had accumulated on the vehicle, one of the issues of being on open display. Dust has to be removed as it attracts moisture, potentially promoting corrosion of the metal surface. As well as dust the vehicle had cobwebs and flies to be removed.

Cleaning brushes of various sizes and a blue microfibre cloth laid out on a plain surface.

Air puffer; large soft brush; smaller brushes; microfiber cloth (avoid!).

The two key tools I used were soft bristled brushes and an air puffer. These tools help to lift the dust and can reach into small cracks. Avoid using cloths as these will catch on loose paint, and rub the dust across the surface causing small scratches. Start from the top of the vehicle to allow dust to fall down as you lift it. A good idea is to have a vacuum cleaner on hand to pick up dust from the air as you clean. Use large brushes and the puffer for the general surface. A small paint brush can be used to lift up dust trapped in tight spots. As a military vehicle, the M5 had various components along the outside. These took more patience to clean as they had many areas that had trapped dust. Components were also made of different materials; rubber tyres, wooden cases, glass headlamps, metal bodywork. Try to use a different brush for each material type, particularly with rubber as it had accumulated the most dirt.

Paint Consolidation

Some areas of the vehicle’s surface had flaking paint. I consolidated the paint in areas deemed to be at risk of breaking off. To do so I used HMG Paraloid B72. With this I carefully brushed under the flakes to adhere them to the metal surface. I then put on a coat of B72 that covered both the paint and exposed metal surface. B72 is a reversible adhesive that can easily be removed with acetone should a future conservator wish to do so. It also remains clear and stable. An issue I had was that the HMG version available to me was too tacky and difficult to apply. I recommend using a B72 product with a smaller percentage of B72 to acetone, as it would be easier to apply and pose less risk towards the paint. Once the adhesive had dried the flakes felt secure. Always consult a conservator or collections staff before making a decision to consolidate the paint. I only chose to do so in the worse of areas.

Sealing and Limiting Corrosion

Metal and paint flaking, showing signs of rust and corrosion.

Corroded metal and consolidated flaking paint during application.

The vehicle's roof had exposed areas of metal that had corroded at some stage in its life. This metal was exposed as paint in the area had flaked away. Being on the roof they were likely to again be covered in dust at some stage, creating the possibility of further corrosion. With this in mind, I decided to seal the areas in micro-crystalline wax. This would serve as a barrier, limiting dust and moisture interactions with the metal.

I began by cleaning the area to ensure all dirt and dust was removed, using the same techniques as earlier. The paint around the metal area was consolidated using the above method. I then applied the wax using a cloth, ensuring it coated the entire area to create a complete barrier. Initially it makes the corrosion appear much darker, but after it has dried it returns to its original colour. The wax will need to be removed and replaced in one year's time. Again, consult a conservator or collections staff before making the decision to apply wax. I did so only in areas that I believed to be at risk of future corrosion.

Reattaching a Component

A wooden piece of the vehicle had detached from the main body, likely due to visitor interference. The majority of the original screws were missing, and parts of the wood were damaged. Reattaching the object with screws was out of the question. The wood was too weak and shiny, new screws would look out of place on this old vehicle. Adhesive was also ruled out as a future visitor interaction would likely break the wood rather than the adhesive bond.

I reattached the piece using Nylon thread. The component supports its own weight when in the correct position and just required to be secured to safeguard it from being knocked off. I used the Nylon to anchor the piece to the main body of the vehicle, using the stronger screw holes of the component and holes within the vehicle frame. The clear thread is barely visible unless you are looking for it. The vehicle's aesthetics remain intact, and the piece is now secure.

A man looking closely at a green large vehicle inside a museum gallery.

Before during and after component repair.

Further Problems?

Large metal pipe with blue substance forming on the surface.

Corrosion under the vehicle.

While inspecting the vehicle I found some severe corrosion under the vehicle body. One of the pipes is covered in a blue corrosion product, likely to be copper sulphate. Should this corrode through the surface of the pipe, whatever oil or liquid remains inside may one day find itself spread across the museum floor. Research is currently underway on this issue.

Summary

Overall, assessing and treating this vehicle was unique due to its size and number of components. It was the first industrial object I have had the pleasure of working on. Here is some advice for those who look to treat or clean a similar object:

  • Don’t treat it as a single object, but many components and materials joined together
  • Make sure you begin cleaning at the top to allow dust to fall down onto areas yet to be cleaned
  • Be conscious of the object’s surface when cleaning, using suitable equipment
  • Be wary of vulnerable areas such as paint and components (even if it is an armoured vehicle!)
  • Expect to find problems along the way
  • Have a head for heights!

A man stood atop a tall ladder reaching over to clean the top of a crane, attached to a vehicle.

Head for heights!

Josh Seymour, MSc Conservation Practice student, Cardiff University, wrote this blog on a summer placement with the Museum.

Instagram: joshseymourconservation

Twitter: @joshseymourcon1

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