paint

Swammelstein Rolls-Royce

Paintwork questions:

Question:

I have just purchased a late 1973 Silver Shadow So far most everything appears to be in good shape with exception to the paint. I've noticed that on a lot of the older models the paint has "cracked" or "Spider veined" as I've heard someone call it. I want to have a bare-metal respray (which I know might cost a considerable amount), but I was wondering why this happens and what can be done to stop it? Is it caused by poor care or just a trait of the paint. I live in florida and the car was originally purchase in California. Could it be from the excessive heat? Thanks for any insight you can provide.

Answers:

If the 'cracking' is mainly around the windscreen posts, radiator grille and where the roof meets the trunk, it's probably lead cracking - very common. RR used molten lead as a filler until perhaps the early 80s. When respraying, most shops get rid of the lead and use a synthetic filler before painting, I'm told. Also the finish on these cars varies in thickness, sometimes up to an eighth of an inch. (I once inadvertently left a bolt in the trunk lid channel while working on one of the hinges... when I closed the lid there was a crack like a pistol shot & the result was a chip over 1/16" deep, with grey primer still on the metal.)

Cracks can fall into several categories.

Lead cracks commonly found at the base of the screen pillars and scuttle, at the top of the front screen pillar where it meets the cant rail, anywhere on the upper rear quarter panels, the rear deck. They are also common around the bonnet apeture.

Lead cracking, in all the time I have worked with these and later cars has been a problem and in fact remedial warranty work was carried out on many of them even when just a few months old.

Lead is traditionally used as a filler in coachbuilt cars and generally the lower the production figures the more lead you will find, consequently the Corniche has more lead than a Shadow and around 70lbs is used in each car. On the Camargue this figure was much higher. The higher the lead content the greater the number of paint cracks and other defects.

During warranty work on these cars I was constantly amazed at the poor quality of the lead work, it would always show numerous holes and inclusions. Other manufacturers, Jensen for example, used much more lead (about 200lbs in the Interceptor) but lacked the lead related problems because in my opinion the lead work was superior. Cracks still developed but were fewer and the smaller contamination related paint defects were very rare.

Leading is a process that requires some degree of skill but put simply the body solder (70%lead & 30%tin) is applied to the surface in small lumps. The pre tinned surface and the solder bar are heated to the exact temperature, the bar pressed against the metal to which it adheres and then the bar is twisted. This is repeated until sufficient solder covers the repair. The next stage is to apply heat over the numerous lumps and blend them together, this and the final shaping is done with a wooden'"paddle" soaked in an animal fat called tallow while constantly keeping the solder in a plastic condition by keeping the temperature constant. This is where most problems occur as air pockets can occur as the individual lumps are pressed together. Any such pockets will contain the tallow and if this ever finds its way to the surface it will cause the paint to lift. This is the cause of most lead probems. Large amounts of these pockets can even cause the solder to be porous and also weaken it, particularly if these pockets are large. I have seen voids over one inch across.

Having said that Rolls-Royce lead loading is not the best in the world that does not mean it should all be ripped out and replaced with plastic filler. Instead prior to commencing any paint repair a detailed mark up sheet should be compiled that details exactly what lead defects are visible. There will be many leaded areas that will show themselves once the paint is removed, if these have not caused a problem since the car was built they never will, leave them. Areas where are problems should be attended to appropriately and rarely is it necessary to remove all the lead from an area and replace it with new. Instead many repairs can be attended to by tackling the defect itself. For example taking out the crack, applying lead in that area and blending the whole together. This is where the mark up sheet is essential, what may have been an enormous crack may be almost invisible at the point from which it started.

Lead cracks also appear in the areas I mentioned above due to flexing of the bodyshell. Many Shadows also exhibit paint cracking and it may not even be lead related at all but simply due to excessive thickness of paint. Obviously you have no control over this as it is inherent in the design. The problem is compounded by excessive paint thickness. The thicker the paint the more likely cracking will develop. Corrosion at the base of the front screen pillars is also very common on the Shadow and this in all cases requires removal of the front screen and sometimes the dash board top roll. In this case although cracks will be present so too will a raise area over of lead like a large shallow bubble.

There is no one single way to remedy all lead defects but you must use the mark up sheet after conducting a very very thorough inspection. Most lead repairs can then be dealt with locally although it may be necessary to remove some areas of lead and start again. Despite all of its problems lead, properly applied can for certain purposes be superior to plastic fillers so I would stress if its OK then leave it. What I would suggest however is to try and seal the lead behind a thin layer of fine polyester filler as this does help to reduce the number of lead related defects showing through later. Any areas showing inclusions should be treated this way.

Paint manufacturers have a magic figure of 12 thousandths of an inch as an upper limit to paint thickness. Most production cars start off with around 4 thou and each subsequent set of colour coats would add about 2 thou. This gives a good margin for later repair work. The shadow left the factory with typically 8-10 thou but this varies considerably over the surface of the entire car. This allows for maybe only one additional set of colour coats before the 12 thou limit is reached. As a lot of reworking was done in the factory before delivery to the dealer some cars already, in theory, should not have been painted without stripping. You can understand why stress cracks quickly appeared on these cars where the shell flexes. Another consideration was the cellulose top coats which are a very brittle hard paint finish. Stripping the paint from a car is an expensive task and so in most cases the paint thickness was added to during repairs and with it the likelyhood of cracking. Bridging is also common on cars having excessive paint thickness. This is where the paint rather than following concave sharp details, like the swage below the chrome side mouldings, lifts away from the surface. The only remedy for these defects is a strip to bare metal.

Crazing or checking as it is otherwise called can result due to excessive thickness combined with thermal stresses. It can also be caused by incompatible paints being used during refinish. Different paint resins, eg TPA, cellulose, urethane all exhibit different rates of expansion due to heat. Applying cellulose over TPA results in guaranteed cracking especially over the bonnet.

Paint also has a life span and with the cellulose used on most shadows the paint manufacturers only really commit themselves to around four years. Obviously it will exceed this but time and usage will take its toll. The process is complex and I am not a paint scientist but my understanding is the cellulose molecule under various chemical actions eventually loses one atom and changes to sucrose. Such reactions do not occur with modern two pack paints which use different resins in which the ends of the molecules are bonded together to form a polymer. In normal use and with care this type of finish is indestructible.

Some people claim that the finish with modern two pack finishes is not as good as the original. My answer to that is a painter with the appropriate skills and who is prepared to put in the effort can produce a finish that mimics the original cellulose so well even the most discerning judge would be hard pressed to tell the difference. Unfortunately these skills are not present in the average paint shop now and using traditional flatting and polishing with modern paints is not recommended. It can be done but it requires a lot of effort.

A last word of advice. make sure your paintshop keeps the primer thickness down in the swage I mentioned and make sure they are meticulously clean in this area prior to painting. Either excessive thickness or contamination, usually caused by flatting residues will cause bridging.

Question:

A friends son accidentally knocked a 3/4" chip of paint off of the bonnet edge of his Shadow. We were absolutely amazed at the thickness of the paint.

In your experience, does a newly-painted Rolls (primarily the Shadow series or earlier, I imagine) look "odd" when it has been stipped to bare metal and repainted with modern products? Considering the thickness of the paint, etc.

Answer:

Yes, no and it depends. I'm sorry there is no straight forward answer but let me explain.

YES

Modern paint materials are formulated to enable the average paintshop to reproduce the standard finish on an ordinary car. Imagine the difficulty they would otherwise have trying to reproduce the textured finish typical on most cars if the paint they were using flowed out like glass. In my opinion the best paint finish in the world is found on Aston Martin and Rolls-Royce/Bentley, in that order. Both manufacturers use products not normally found in production, instead they use paints formulated for refinish use or in other words the very same materials ordinary paint shops use. If you take any Rolls-Royce to a Mercedes specialist and get them to re-paint your car, regardless of whether it is an early or late model, then YES it will look wrong if it exhibits the substantial texture MB deem acceptable.

Traditional manufacturers of fine motor cars have long used a standard process to produce the expected level of finish. With the air dry materials Rolls-Royce used prior to introduction of modern finishes two sets of colour coats were applied over the previously sanded epoxy primer coats. After the first set which consisted ot three coats of paint the car was baked. The finish at this time is, to be kind, very dissapointing, but its purpose is to provide a good base for the final colour set. The baking drives the solvents from the paint film which is then wet sanded, Rolls-Royce use the peculiar term "boneing" to describe this process and this dates back to olden times when apparently cuttle fish bones were used by coachbuilders prior to the introduction of very fine synthetic abrasives. The final set of colour colour coats is applied using a slightly differnt technique and using a different thinner. After further baking the vehicle emerges with a smooth slightly matted finish. This is again wet sanded with a ultra fine abrasive to remove all trace of texture. Once the paint surface shows a fully sanded matt finish it is now polished by a machine normally fitted with a lambswool mop and using a suitable polishing compound. This produces a high gloss on what is now an almost perfectly flat, glass level finish.

With old type air dry materials this is a time consuming process but with perseverence an extraordinary standard of finish can be achieved. With modern finishes however it is a different story. The paint manufacturers advise against sanding and polishing top coats because of the difficulty in restoring the shine. Many of their paint representatives even claim it is impossible and I recently had to demonstrate the technique to a disbelieving Mercedes paint shop foreman before he would agree to improve what I considered to be an unacceptable finish on a 600 Pullman they had stripped and painted. It is possible with a slightly modified and much effort and patience, so in answer to your question will a modern finish look wrong on an older car then NO, not if it goes through the right process.

IT DEPENDS

Non metallic finishes older type finishes exhibit a high gloss and will look similar to modern materials. Frequently though modern "solid" colours are applied as a two layer system and this includes some Rolls-Royce colours. The coloured basecoat is overcoated with a clear lacquer. This produces the highest gloss but when viewed obliquely nearly all of the light is reflected from the surface, this produces a highlight. Colour is percieved with, for example, a blue car, by all the other wavelengths of the spectrum being absorbed by pigments in the paint and the remaining blue light being returned to the observer. The car therefor appears blue. If all the light is returned by the lacquer before it reaches the pigment then it becomes difficult to tell when viewing obliquely whether a dark car is dark blue, dark green, black etc. So here IT DEPENDS

Prior to the introduction of modern two pack, chemically hardened paints by Rolls-Royce around 1992 all metallic finishes were termed single layer. In this system the metallic paint film provides colour, effect, gloss and protection. This contrasts with the now long standard technique of applying a lacquer giving gloss and protection over a basecoat that is only there to provide colour and effect. Sanding and polishing a single layer metallic paint film is incredibly difficult and can sometimes reduce even the best painter to tears. To give some idea of how difficult you can reckon on the three colour coats that make up one set totalling a maximum of two thousandths of an inch. The final coat therefor will be about one third of this or a little over one half of one thousandth, about 0.0007". Both sanding and polishing, which is entirely carried out by hand and eye, can only penetrate this last layer by a small amount however. As the paint film dries the metallic content sinks slightly below the surface and all sanding and polishing must be carried out before the bulk of the metallic content is exposed otherwise a light colour patch called a shear develops. All polished single layer metallics will have some evidence of some of the metallic flakes breaking the surface and disrupting the gloss. The higher the metallic content the lower the gloss. Even from new light colours like silvers, pale blues etc left the factory with a lower level of gloss than darker colours. Durability is similarly affected with dark metallic colours retaining their gloss for longer. A modern clear over base metallic finish will exhibit a slightly higher gloss than a dark single layer metallic and a much higher standard of finish than a light single layer metallic. For the reasons mentioned in the previous paragraph clear over base finishes will also tend to mask the colour when viewed obliquely compared with single layers. So, IT DEPENDS on exactly how well you knew what each of these colours looked like when it left the factory. There are not that many people who have this experience.

The biggest single problem you will have getting any Rolls-Royce painted is to find someone who knows what the correct standard of finish is. If you put your car into a Mercedes approved paintshop they may try and do the best job they have ever done which may well be significantly better than than the cars around them but it is still unlikely to be good enough. Unless he is surrounded by cars like Aston Martin, Rolls-Royce or Bentley a painter is at a significant disadvantage. There is no real answer here unfortunately but the only comment I would make is that by the time a painter has reached the correct standard he has been working in the realms of diminishing returns for a long time. This kind of quality may seem disproportionately expensive but once you know what is involved you at least begin to appreciate where the money goes and that there are no short cuts.

Cracks can fall into several categories.

Lead cracking, in all the time I have worked with these and later cars has been a problem and in fact remedial warranty work was carried out on many of them even when just a few months old.