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Solartex alternative?

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John Laird18/11/2018 11:42:32
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Posted by Don Fry on 17/11/2018 18:42:23:

John, the gold original IMPEX, or the silver thinner version. Seems to be two products. And what's it like, water based or petroleum smelly?

Don,

I use the gold original - not tried the thinner version. No smell.

Ronaldo

that looks like its the same but the impex has a convenient spout for controlling the amount used

Ronaldo18/11/2018 12:04:02
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Ok John, will take a look at Impex also.

Thanks.

David Mellor19/11/2018 14:24:32
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Posted by PatMc on 17/11/2018 22:10:56:
Posted by supertigrefan on 17/11/2018 18:21:00:

I've just covered a trainer in nylon and water based varnish, it's the first time I've used nylon and would like to do so again. I'm interested in how you get a sharp finish at the cut edges? I have 'furry' edges which I have improved with a film iron.

In ye olde days I used to run some un-thinned dope along the furry edges, leave it to harden - 24 hours at least- then sand it off with fresh medium to fine wet & dry paper (used dry) on a sanding block.
I think the same method should work OK with WBV but it wold probably need about double the time to harden before sanding.

I've now done some covering with tissue over laminating film using both dope & WBV. I used tissue because I wanted to retain the vintage appearance & laminating film to make it puncture proof over the open structure. One of the advantages is that, because of the underlying film, the tissue doesn't need as much dope (or varnish) for a satisfactory finish.
At some time in the near future I intend re-building a very old 6ft+ span vintage model I was given. It will be covered first with laminating film then probably with nylon. I expect that, as it did with tissue, the film will reduce the amount of dope required.

Edited By PatMc on 17/11/2018 22:13:33

I've used exactly the same technique and found it works extremely well. laminating film is cheap, so is wet-strength tissue (I get mine from Colin Buckle). I buy dope by the (US) gallon, so it is cheap too. Good for lots of vintage stick-and-tissue models - especially big ones.

p1040447.jpg

Stearman6521/11/2018 14:35:10
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Is this the new Solartex, it is for me if she does my model???

**LINK**

Don Fry21/11/2018 15:44:07
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Yes, very nice.

Calling David Mellor, (font of such knowledge), this laminating film, tissue system. How does the weight compare to Solartex?

David Mellor21/11/2018 17:06:26
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Laminating film by itself is roughly 1/3rd the weight of Solartex (i.e. a lot lighter)

Laminating film plus tissue and dope is roughly 2/3rds to 4/5ths the weight of Solartex (i.e. a bit lighter).

 

To put that as a weight saving into context, consider the Majestic Major. It has a nominal 88" wingspan (it is actually 89" on my plan), and is a moderately large model with quite a long, boxy fuselage (60" x 9" x 5" ) and very large tail feathers. I covered mine with laminating film only, and it added 1.55 ounces to the fuselage and 0.9 ounces to the tail feathers, so 2.45 ounces for the entire structure excluding the wing.

 

For comparison, eflightray covered his Majestic Major with Solartex and reports that it added 7.5 ounces to the fuselage and tail feathers (ref: **LINK**  ) compared with 2.45 ounces for mine for the laminating film only (no tissue).

 

The additional weight from adding tissue and dope depends on the tissue used, but will typically add at least the same again as the underlying laminating film, unless very light tissue is used.

 

The tissue is applied wet (damp, more accurately) with dope as the adhesive to bond it to the laminating film. This means that the "weave" of the tissue is already partly filled when it dries out and tightens up. This in turn means that it subsequently absorbs very little additional dope in subsequent coats because the dope cannot seep through the laminating film to be absorbed by the balsa. When the last coat is dry, the tissue sands back really well to give a nice flat surface that takes paint really well.

 

Perhaps the biggest difference is cost (and, of course, availability).  Laminating film is dirt cheap, and extremely good at going round compound curves - though you need 200 degrees C on the iron to pull it nice and tight.  Good basic wet strength tissue is cheap and if you buy dope by the gallon, it is cheap too.  If you use really lightweight tissue, then I would expect the resulting composite covering weight to be roughly half that of Solartex, and you'd still have bags of strength from the laminating film.  The tissue surface looks good (i.e. vintage) but adds relatively little strength - most of the strength coming from the laminating film.

I buy my dope from LAS  Aerospace here: https://www.lasaero.com/products/article/M03QA76XL

One thing well worth saying - especially in view of the fact that it is the laminating film that provides the bulk of the strength, is that laminating film can be painted very successfully.

p1030414.jpg

 

Dave

 

Edited By David Mellor on 21/11/2018 17:33:44

Gordon Whitehead 121/11/2018 17:31:20
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Looking on Ebay, laminating film comes in many different thicknesses, widths and lengths, and a roll can cost quite a lot, even if it's cheap per sq yard.

What's a good thickness and width to buy for starters?

Is the dope used non-shrinking, or shrinking, and where can it be bought by the gallon? I've had cellulose thinners from Ebay before, in fact cellulose is my favourite paint.

(EDIT - sorry, I didn't see the pic on the previous post!)

Does the dope adhere completely to the laminating film or does it peel off under some circumstances?

Presumably the laminating film's adhesive is heat-activated like that of the modelling films. Can it be made to pull round compound curves, eg a rounded block balsa wing tip, with heat without wrinkling, and then does the overlap adhere well enough so that it doesn't peel off later?

Obviously there's a technique to be learned and I'm wondering if there's a thread or blog somewhere with useful hints.

Kind regards

Gordon

Edited By Gordon Whitehead 1 on 21/11/2018 17:32:28

Edit no 2.  It's probably worth using aircraft cellulose as it'll be plasticised.  I've found that coloured car celluose can craze when used on, say, solartex and make your model look very aged! 

Edited By Gordon Whitehead 1 on 21/11/2018 17:38:08

David Mellor21/11/2018 17:54:04
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Hi Gordon

There are quite a few threads on RCGroups on the subject of doped-tissue over laminating film (also known as doculam and newstuff).

Here's one such:-

**LINK**

If you check out that thread, then you'll find a contributor called 'Sundancer' - his real name is George Stringwell and he is a very well respected modeller and (IIRC) has published an article on the technique. Anyway... search all the RCG threads he has started as well. Read the second post (the first by Sundancer) in that thread for most of what you need to know.

I followed Sundancer's recommendations and they work perfectly. I use 38 micron laminating film.

The laminating film needs no Balsaloc and it sticks to balsa extremely well. Iron it on to the wood (keep the iron away from the middles of panels until you are ready to tauten), keeping it taught without shrinking. To shrink it, and to pull it round curves you'll need the very unusually high temperature of 200 degrees C. It overlaps itself extremely well too. It doesn't peel off unless you pull it. Practice does make perfect......

Dave

 

Edited By David Mellor on 21/11/2018 17:57:55

Gordon Whitehead 121/11/2018 18:27:57
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Thanks Dave, I have a good root around on RCG!

Gordon

Don Fry21/11/2018 20:03:42
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Cheers Dave, not a system for me, with a fuelproofer on top.

Don Fry21/11/2018 20:19:53
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Posted by Don Fry on 21/11/2018 20:03:42:

Cheers Dave, not a system for me, with a fuelproofer on top.

On second thoughts, what paints go on the film, sans tissue.

David Mellor22/11/2018 14:07:30
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I have no experience of painting directly on to laminating film. There are quite a few threads on the subject, and I seem to remember Sundancer explaining how he goes about it.

Given that dope doesn't damage laminating film, I'd expect any solvent based spray paint should be OK, though I have read that you may need to degrease and fine-sand (with foam backed sander) first for proper adhesion.

Stearman6522/11/2018 14:33:09
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Posted by David Mellor on 22/11/2018 14:07:30:I have read that you may need to degrease and fine-sand (with foam backed sander) first for proper adhesion.

I would do the de greasing & sanding before applying it to the model if that is the case? Otherwise you could get missed or over-sanded patches.

David Mellor22/11/2018 15:25:01
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Posted by Stearman65 on 22/11/2018 14:33:09:
Posted by David Mellor on 22/11/2018 14:07:30:I have read that you may need to degrease and fine-sand (with foam backed sander) first for proper adhesion.

I would do the de greasing & sanding before applying it to the model if that is the case? Otherwise you could get missed or over-sanded patches.

Yes, I think that would be simplest all round. I imagine that sanding laminating film already bonded over open structure would be a horrible job....

PatMc22/11/2018 16:19:57
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IIRC Sundancer (RCGroups vintage section) uses matt film. He has loaded photos of a WW! biplane that was painted directly on to the film several years ago & still in good condition.

 

Edited By PatMc on 22/11/2018 16:21:08

David Mellor22/11/2018 16:55:10
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Posted by PatMc on 22/11/2018 16:19:57:

IIRC Sundancer (RCGroups vintage section) uses matt film. He has loaded photos of a WW! biplane that was painted directly on to the film several years ago & still in good condition.

Edited By PatMc on 22/11/2018 16:21:08

Yes, you're right Pat. He uses semi-matt film. I'm not sure what the stuff I use is (I bought it ages ago), but it looks to me like it is probably gloss finish, so not much good for painting unless sanded lightly first.

Here's the Sundancer link:-

**LINK**

Dave

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