EXACTO BLUES

part 1

by Juan Carlos Rovetta

Old times’ nostalgia and a quest for blue and gold

When reading the February issue of NZFMM I found the contributions of Neil Pluck and John Ince. I could not avoid remembering Alberto Richini, founder and former manager of Exacto, while hand-drawing the gold lines of the cross-hatched plates for the L sets he specially prepared now and then for his special customers. You do not sell many of those, and each set is almost one of a kind. He was an outstanding mechanical engineer and draftsman, and those gold lines displayed all the beauty of their unspoiled and yet vibrant symmetry.

I have noticed that blue and gold has the ability to arouse strong feelings and perplexing enigmas. Many, most I feel, consider it is something to be placed at the acme of Meccano aesthetics. Others always took it for granted that ’gold’ was nothing but an optimistic way of calling those yellowish greenish and sometimes faded lines criss-crossing the plates. Well, they had been tricked by Binns Road, but not quite as much as some like myself. As a kid I had to bear the sufferings of growing up wondering about those mysterious lines that the manuals showed so distinctly in all the models, ... but had vanished away from the parts! Why was it that mine looked so plain red? It was not until I grew well over 30 that an older and wiser man showed me the truth. It was like an epiphany. Yes, there was something else, glorious and yet unseen! There was a world in which strips and girders were golden like wheat, and plates blue like the deepest sea with their surfaces pierced by rays from the sun. It was the real blue and gold world!

Getting into technicalities

Somehow this was the seed of the quest, and it rested still until last year when we decided to redesign all our finishing processes. Although we considered that Exacto was already offering an excellent finish, we wanted to offer the best finish available, and would not settle for less. Not quite unexpectedly, we put blue and gold in the centre of the project and made it something as the main challenge.

At an early stage of this development we defined our design requisites and determined that certain characteristics should be maximized: corrosion resistance, adherence, flexibility, colour stability, colour repeatability. And, above all, it should be very affordable.

We studied and tested several processes, drawing information mainly from the experience of the car building industry. We concluded that a three-stage process would satisfy all our design requisites. Going from the inside out, it consists of the following layers: electrolytic zinc coating with chromate passivation, wash primer, and two-component polyurethane coating.

Zinc gives sacrificial protection to the base metal when it is exposed and the chromate passivation gives the needed corrosion resistance. Wash primer assures adhesion of polyurethane paint, which is the first barrier to environmental aggression. This coating is of the kind used on luxury cars, and its resistance and colour stability is excellent.



The excitement of colour hunting

So far we had solved the structural aspects of the finishing process, but what about the aesthetic issues?

Colour matching and repeatability were no big technical deal with computerized equipment. In fact, the availability of this process for liquid paints is what decided us against electrostatic powder coating, which offers too many chromatic restrictions.

The real problem was making a decision on the 'right' blue and the 'right' gold.

After evaluating over a dozen original samples of blue we discarded the paler shades. These were probably more a result of pigments fading due to low stability than a consequence of low ex-factory repeatability. The choice was made for a deep 'cobalt' blue, and seemingly many have already fallen in love with it.

For gold it was not quite the same. Choosing from original samples that ranged from shades of molasses brown to copper red was one easy thing if compared to obtaining a natural finish with deep light reflection. We had to try and discard many formulations. They just looked fake, a sad resemblance of gold, a poor plastic imitation. So much for car body painting products. After additional research we turned to the graphic arts industry. The product that we finally selected turned out to be the closest one can get to grounding a gold ingot into powder. Wow! The thing gave a deep glitter and an excellent match with our chosen samples. We had hit the target.

We also found a solution for cross-hatching in the graphic arts industry. Hand drawing was out of the question if we wanted affordable costs and consistent quality. One thing we had in mind was assuring the alignment of the cross-hatching with respect to the holes, so that big models would not be spoiled by shaky lines. After trials and errors we could succeed in adapting to our needs a printing technique that met all these criteria. Furthermore, in order to enhance the results, we decided on two-component epoxy inks in order to assure the highest resistance for the gold lines.

(please click on 'Exacto & Meccano - 2' to read continuation)

To read more on Exacto and Meccano you can visit the following links:

The world of Meccano presented at the International Society of Meccanomen at http://www.internationalmeccanomen.org.uk/

Historical notes on Exacto and Meccano in Alan Asplen's website at ttp://www.btinternet.com/~a.esplen/mecc.htm

Historical notes on Exacto and Meccano in Wes Dalefield's website at http://www.dalefield.com/mwes/history/index.html

Historical notes on Exacto and Meccano in the Girders & Gears website at http://www.girdersandgears.com/exacto.html

A downloadable collection of 3-D Exacto and Meccano parts drawn by Anthony Els at http://www.mecworld.co.za/ant/

General information on Exacto and Meccano presented by CMAMAS (Canadian Modeling Association for Meccano and Allied Systems) at http://www.memeshadow.net/cmamas/meccano/cmnsf.html

Historical notes and general encyclopaedic information on Meccano in Wikipedia at http://en.wikipedia.org/wiki/Meccano (English) and at http://fr.wikipedia.org/wiki/Meccano (French)

 
 
 
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20-11-2017 | 06:29:01 GMT-3:00