With the large selection of iron-on covering materials which are currently available, it is inevitable that someone will ask, 'Why another covering film?'. This was our feeling until we tried it! The difference with 'Micafilm' is hard to define, but a couple, but a couple of hours spent on covering with it (and the first attempts were not too successful) turnedthe writer from one who was frankly sceptical into a near enthusiast.
Film texture is very similar to a fairly coarse rag tissue with a plastic film attached to oneside. This film is not the sort of smooth, high gloss, surface usually associated with covering films, but a semi-gloss, slightly textured finish. The combined tissue/film does not have any adhesive attached to it and can, therefore, be applied with either surface outermost.
With the film surface outside, the finish has an uncanny resemblance to a well doped coloured tissue finish, applied by a superlative modeller.
If the tissue surface is uppermost. it can be doped, painted, or finished to your choice.
The actual adhesion of the film is by use of another Coverite product - 'Balsarite'. This is a heat activated adhesive, similar to that normally used for iron-on films, but is applied to the structure by brush before covering. This has some notable advantages, the principal one being that you can choose where you want the covering to adhere - no 'Balsarite' - no stick!
A less obvious advantage is that the wood can be pre-treated to produce a harder surface and thus avoid those all-too-easily-applied dents which are a feature of conventional film covering. If, for example, the structure is given a couple of coats of clear dope and sanded smooth before covering with adhesive backed film; the result would be lots of hard to remove air bubbles. With 'Balsarite' applied to the structure after doping this does not happen.
One minor disadvantage is that you have to apply more 'Balsarite' before 'Micafilm' can be overlapped on to previously applied film. This becomes of more importance if you plan to use 'Micafilm' to apply a contrasting trim colour. One solution here is to use adhesive backed film for the trim.
The guinea pig for this first attempt was the tail unit of a Golden Era Kits Taibi 'Power House', with a tailplane span and chord of 31.25" x 10.375" and a thickness of a mere 1/2".
As a guinea piglet the somewhat smaller fin and rudder were tackled first. All the wood was given two coats of clear dope and sanded to produce a smooth hard surface. 'Balsarite' was then brushed on to the areas where the covering was required to adhere.
Prior consuliation with Flair's Dudley Patterson (the importer) suggested that less heat than usual was required for the actual sticking and this proved to be true. One side of the fin was soon covered and an attempt made to shrink the resulting film covering.
It was immediately apparent that the film has a pronounced 'grain' (this runs down the length of the roll) and that there was lots of shrinkage down the grain, but little, if any, across it. At this point I was less than impressed!
'Ah well, it's the knack as you need,' thought I, and proceeded to cover the other side, taking great care to keep the film as taut as possible across the grain while doing so. Much better but still not quite right.
The rudder went much better with quite reasonable results, so I promptly stripped and recovered the fin and made a much better job at the second attempt.
So, on to the tailplane. The bottom was covered first, laying the grain spanwise and again keeping the film taut across the chord. More 'Balsarite'. was brushed around the edges and the top covered in a similar manner. It was necessary (or so I thought) to make slits over the spars towards the tips to 'lose' some of the film.
After shrinking, it looked very presentable apart from a few small wrinkles around the tips.
Another phone call to Dudley produced the comment 'Try more heat', so I did! After cranking the heat setting up to a startling degree the wrinkles suddenly disappeared and a beautiful drumtight surface appeared.
'What did all this shrinkage do to that thin tailplane?', you might ask. Well it warped it of course! But, twisting the tail straight and re-applying the iron produced a straight tailplane!
I shall cover the rest of the model with the same material; any questions?