The first attempt to build a dome didn't produce the hoped for results. So I decided to order one of these magnificent, but unfortunately, also very expensive, R+J superdomes. It took some months before it was delivered and so the construction period of my R2 was extended again

I used this dome, as with its predecessor, only as a master model, in order to be able to create a silicon mould, from which I could then produce GRP domes.

 

After some days of sawing, cutting and sanding the dome was ready for assembly.

Many of the individual panels had to be clamped into position for while the adhesive hardened, otherwise they could have come apart at some of the corners.

After all panels were glued on, all joints and edges were sealed, in order to prevent the silicon from flowing in.

Now the first layer of silicon was poured on. After the silicon had hardened a little, further layers were added, the finished silicon mould was thus some 3-4 mm thick. In order to prevent the liquid silicon from running off before hardening, I rotated the dome vertically for some hours.

I manufactured a mould from MDF and polystyrene, which was pushed over the dome during the silicon mould production. Then the dome was placed into a horizontal position and the silicon that ran off now formed a "retaining edge", which later prevents the silicon mould from collapsing into the supporting form. Next the Dome was replaced back in the vertical position so that the last layers could be laid on. For more information regarding the "retaining edge" see "silicon moulds".

This picture shows the finished silicon mould and the already removed "casting form" for the retaining edge.

Don't remove the silicon mould from the master model in this stage of production. Without an existing supporting mould the silicon collapses into itself and the production of an accurate supporting form is no longer possible.

The finished supporting mould with inserted silicon mould.

The first attempts were not satisfying enough and so I manufactured further duplicates and experimented with different Gelcoats and colouring pastes.

Unfortunately many small air bubbles, develop with hand laminates, particularly at the edges, and so I had to fill all the bubbles first. Afterwards the dome was sanded with 1200 wet sandpaper.

The structure of the final lacquer finish:

1 layer primer

3 layers blue metallic applied at 15 minute intervals

2 layers clear lacquer

After waiting for 2 days add 2 layers silver and 2 layers clear lacquer.

I used DupliColor primer, DupliColor 0-0600 (silver), DupliColor 20-0802 (blue metallic) and DupliColor clear lacquer.

The painted dome showing ageing and weathering effects.

Further pictures (click to enlarge).

 

 

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