Coach-painting

Traditionally coach-painting involved the manual application, using specially selected brushes, of numerous coats of coach-enamel. The paintwork was rubbed down between coats so as to achieve a smooth finish. The last few coats consisted of a mixture of paint with clear lacquer, the amount of paint in the mixture decreasing with successive coats. The last two or three coats would consist of pure lacquer. The result was a finish of great depth and lustre. However this process was extremely labour-intensive. The advent of the spray-gun and cellulose paints introduced a completely new dimension in to the whole process.

In the past fifty years the painting process has evolved yet further, with different paint systems being introduced, and then fading from the scene. For many years cellulose paint was the norm, which relied upon solvent evaporation to harden. But ultimately this was overtaken by two-pack paint systems; these rely upon a chemical reaction to take place within the paint layer to enable it to cure in a short time span. However, the chemicals involved pose a significant health hazard. As a result another technology utilising water-based paints has been introduced, and it is this that the modern car industry relies upon.

When repainting a pre-war coachbuilt car a number of factors have to be taken into account. Unlike a modern monococque car body, a coachbuilt body is built on a wooden frame, often on a comparatively flexible chassis frame. The body is panelled in aluminium which has a high coefficient of thermal expansion. Consequently the body cannot be treated as a rigid structure, and this has a bearing on the choice of paint system and the way it is applied.

As in all painting, the quality of the final result is determined by the quality of the preparation. The following is an outline of the processes undertaken at Fiennes Restoration to enable us to achieve the results that we are looking for. A total re-spray from bare metal is being considered; initially the car is presented as a complete and assembled entity.

The process may appear to be very laborious. However in order for the paint finish to look as good after ten or fifteen years as it was when first completed, barring unforeseen circumstances, it is a false economy to introduce short cuts.

1 At the outset a thorough examination of the body is made. Any peculiarities or idiosyncrasies are noted, together with details of any potential problem areas, such as irregular door shut lines. A full photographic record of the car is made for future reference.

2 All external chromework, decorative features, lamps and mirrors are removed. The front and rear windows are taken out. The doors are dismantled, lock mechanisms and window winders being removed together with all door handles. All removable body panels such as doors, wings, bonnet and boot lid are removed from the body shell.

The complete stripping of the body is important, to avoid the presence of unsightly masking lines around unpainted fittings such as door handles in the end result. In addition it greatly aids the preparation of the panels and later polishing.

All loose items of trim are removed and stored safely. It is likely that the interior head-lining will be removed; it will certainly be released along the edges abutting the painted door shut faces. In the case of an open car the hood and frame will be detached and removed.

3 With the coachwork dismantled, the old paint can be stripped. This can be achieved by dipping bare panels such as wings in a bath of an appropriate chemical. At the same time they can be dipped to remove all traces of corrosion which otherwise may become locked in pores in the metal, only to re-appear months or years later. The paint is removed from the main body shell, and panels which are constructed on a wooden frame such as doors, by means of manually-applied paint stripper.

4 With all the paint removed the condition of the under-lying metal can be assessed. Often evidence of older repairs are exposed, plus the effects of corrosion. We endeavour to use as little body-filler as possible in later stages, so repairs to the metal to make good may be required at this stage.

Coach fittings

A photographic record of body fittings
Just some of the body fittings from a Bentley 4 1/4L

5 Now is the time to examine the many items of coach-fittings for damage or wear. These will include door hinges and locking mechanisms, window winders, windscreen frames and opening mechanisms, hood frames and hood latches, and all items of decorative trim. Moving parts will be refurbished as necessary, new windows made, and all items of bright-work will be repaired and replated, if required.

Bentley 4 1/4L

Bentely 4 1/4L by Gurney Nutting in bare metal
This elegant Sedanca by Gurney Nutting, assembled in bare metal prior to painting

6 This stage of the process is most important. Before any preparation for painting is begun the whole car is now assembled in bare metal. All fittings are installed, and every panel is checked for fit and each mechanism checked for correct operation. Corrective work may be needed. Only when we are satisfied that everything fits and works correctly do we move on to the painting of the body. The final thickness of the paint that is to be applied has to be taken in to account when assessing the assembly in bare metal. The object of this exercise is to reduce to an absolute minimum subsequent work on a finish painted panel which may result in local damage to the paint.

At the same time slight defects in the body panels are identified by the painter. A decision is taken as to whether these can be rectified by the panel beater at this stage, or whether the painter will, after all, have to rely upon the minimum of body filler to overcome the defect later.

7 In the knowledge that every part of the body fits with its neighbour it is now dismantled with great care. All parts are stored as sets, so that in the final assembly parts will go back together as they came apart. Each separate panel is removed from the body shell.

Body masked up

Coachwork masked up awaiting painting
Coachwork masked up awaiting painting

8 The body and panels are masked up to prevent those areas that do not require painting from being painted. It will be necessary to renew some or all the masking between later stages of the painting process.

9 Cleanliness during the painting process is also important, to ensure adhesion of the different layers. To ensure that the surface is ready for the next application it is carefully cleaned with appropriate solvents and cleaning agents. Before any paint is applied the surfaces are abraded with a coarse finish to give a mechanical key and then given a further solvent clean.

10 The first layer of paint to be applied is an ‘etch primer’. This keys chemically to the aluminium surface of the body panels to ensure good adhesion, and presents a suitable surface for the application of the next layer.

Bodywork in primer

Daimler sovereign saloon in primer
The same care and attention is given to post war classics as pre-war coachbuilt cars

11 Over the etch primer a thicker layer of ‘primer surfacer’ is applied. Once totally cured this is rubbed down with care to identify the high spots in the panel. Two or three applications may be required, being rubbed down after each, before the painter is satisfied that the panel or body shell is ready for colour. The objective is to create a surface which is as straight or flat as possible, with the minimum of variation. It requires immense patience and considerable skill. The quality of the final paint finish is dependant upon the condition of the prepared surfaces at the conclusion of this stage of the process.

It may be necessary to refit temporarily doors, bonnet or boot-lid to check that when assembled the flatted surfaces do all line up and ‘flow through’.

12 Now, and only now, will colour coats be applied. Three or four coats of colour are used, being rubbed down with very fine abrasive between. Great care must be taken not to thin the layer of paint on high points or edges during the rubbing down.

13 If the required finish is a metallic paint the final coat is a clear lacquer which is applied now. When using two-pack non-metallic paint this is not required.

Coachwork prior to polishing

Coachwork rubbed down prior to final polishing

14 Once the final coat, colour or lacquer as appropriate, has completely hardened and cured it is rubbed down with the finest grade of abrasive paper. All painted surfaces are then polished and finally waxed. This is done by hand or using powered hand tools as necessary.

Final assembly

Coachwork in final assembly

15 Having completed the painting of all the individual panels the coachwork is ready for final assembly. The masking is removed from the body shell and panels for the final time. In view of the precautions taken earlier the assembly process should be completed with the minimum of adjustment to any of the panels or fittings.

The end result: Bentley 4 1/4L with Sedanca coachwork by Gurney Nutting

Some of the cars we have painted

Bentley 3 1/2L

Bentley 3 1/2L with coachwork by Vanden Plas
Bentley 3 1/2L with coachwork by Vanden Plas

Bentley 4 1/4L

Bentley 4 1/4L with coachwork by H J Mulliner
Coachwork by H J Mulliner

Bentley 3 1/2L

Coachwork by Vanden Plas

Skoda saloon

1928 Skoda

Bentley 4 1/4L

Bentley 4 1/4L, pillarless saloon by Vanden Plas
Pillarless saloon by Vanden Plas

1939 Rolls-Royce Wraith

1939 Rolls-Royce Wraith, Sedanca coachwork by Park Ward
Sedanca coachwork by Park Ward

Bentley 4 1/4L

Bentley 4 1/4L, coachwork by Thrupp and Maberley
Coachwork by Thrupp and Maberley

Bentley 4 1/4L

Bentley 4 1/4L, coachwork by Gurney Nutting
Coachwork by Gurney Nutting

British Salmson

British Salmson 'Victoria' Coupe
British Salmson 'Victoria' Coupe

Phantom 2 Continental

Coachwork by Hooper

Bentley 4 1/4L

Saloon by Park Ward