1/24 scale DH Mosquito for rubber power.

[TheLurker]

...this frame is too small to produce the Mosquito's wing panels...

Evening matey.

Dunno if it's any help, but Hobbycraft sell pre-stretched artists' canvases for not many of your Eeengleesh pounds.  They're cheap enough* that you can bin the canvas and keep the stretcher.  I use an A2 one, but they do larger sizes.

I fix the tissue to the frame with glue stick, teasing out as if I were covering a wing or similar.  Let the glue dry for several hours before spraying with water and then set it to one side for however long it needs to dry out properly.  The pic. is from the Chiribiri build.

*And cheaper than buying the wood and making your own.

ETA - Spray bottles. Those sold in Boots' hairdressing section have a very, very fine spray and are under a fiver.  Recommended.

[Prosper]

Hullo Lurk, I must get one of those atomiser spray things.

But regarding the canvas stretcher, I have a problem. When I joined HPA I read of 'pre-shrunk' tissue; but people always described what you have - attaching tissue tautly to a frame of some sort then spraying water. The tissue sags, then regains its tautness as it dries. What has changed? I tried this, and found that it didn't make a distinct difference over using 'un-pre-shrunk' Esaki. Maybe I was misunderstanding something.

Anyway, I wanted to tame the fierce shrinking tendency of Esaki so attached it to a frame that can be stretched whilst the tissue is wet (see the crude frame pictured in my above post - it was only intended to try the idea but I kept on using it). The tissue is then demonstrably stretched, and can indeed be stretched to the point of lifelessness (as in no potential shrinkage left: about to split . . . this is not good generally). Another way of stretching tissue is to make it really wet, lay it on a slippery surface like glass and tease it out with a brush, then clamp the edges so that it can't shrink back to its original dimensions. This is where I find that the brush scuffs up Asuka.

The basic idea then, is to pre-stretch the tissue but leaving some spring in it; painting it as req. whilst it's still on the frame, and then applying it damp so that it still has some shrinking ability to beat the worst of my wrinkle-inducing maladroitness - and damp also to increase the working time of the glue I use before it 'grabs'.

I guess this all describes a specific start-to-finish technique. Others have the whole practice nailed, whether based on glue-stick, dope, PVA or whatever. But however people do the job  I've never understood the 'pre-shrinking-on-a-frame' initial stage.

[Prosper]

Regarding the sandpaper-look of white-airbrushed Asuka, I dug out this photo of the 16" span Piper Pacer I made back in 2013 - see the nice shine on the wings - not the sticky wet-look gloss that comes from varnish - just Esaki and acrylic paint. I will not be covering my new, larger,  Pacer in sandpaper.

Stephen.

[TheLurker]

Hullo Lurk, I must get one of those atomiser spray things.

As sold at Boots the Chemist

You'll probably have to toddle off to your nearest shop to get one.  MrsL wanted one for the ironing but couldn't order one on-line and had to borrow mine until our local shop had some in stock.

But regarding the canvas stretcher, I have a problem...tissue sags, then regains its tautness....

I am a bear of very little brain and what follows may be utter tosh, but my understanding is that by shrinking on a robust frame rather than your delicate flying surface you are carrying the most warp inducing stage of the tissue application process with no risk of buckling that component.  There will still be some "shrink" left in the tissue afterwards, but most of it will be "used up" so when you apply it to your component you can still get a little bit of shrinkage with (gentle) steaming to take up any slack, but it won't be pringled.

After (pre)shrinking the tissue is tauter than before, honestly. You can hear this if you strike the frame with your fingertips.  Before the spray/dry cycle you'll get a dead sound and maybe a very slight rustle from the tissue even if it's not obviously slack. Afterwards it sounds like a drum head and you'll get a definite "boom" when you strike the frame.  The shrink is really obvious if you use corrugated cardboard frames - which I do, see the Chiribiri thread.  If you don't pin the frame down while the tissue is drying it will curl under the tension.

...tease it out with a brush, then clamp the edges so that it can't shrink back to its original dimensions. This is where I find that the brush scuffs up Asuka....

Have you tried gluing long strips of (say) 80gsm paper to each edge and using those as anchors/tenterhooks to pull the tissue out?

[Prosper]

Thanks for taking the time to explain, Lurk.

I might find myself in the vicinity of a Boots the Chemist sometime in the next ten years . . .

Your percussion testing has convinced me, and the corrugated cardboard evidence. I shall experiment. Shrinkage mostly 'used up' is what I'm after. I haven't tried gluing paper to the edges of the tissue panel as handgrips/anchors, but have tried masking tape for same. Masking tape doesn't do the job very well - get the tissue panel taut across one axis, then tugging the tissue crosswise induces waves or wrinkles in the first axis.

I obviously need to review this whole matter - will report in due course.

Another option for the Mosquito is to use my largely vanished stock of coloured Esaki. The model will be mainly dark shades and I can airbrush white where there are to be national insignia and squadron markings etc. The trouble is, I'm saving the Esaki for 'that special model' (or models).

But, 1) What makes me think that this isn't that special model? 2) How will I know when what is that special model comes along?

Now I know how teenage girls in lo-ove feel

Stephen.

[Jmk89]

I suppose, adapting the words of the old advertisement, if it's worth building, it's worth Esaki

[Prosper]

. . .if it's worth building, it's worth Esaki

Yeah, but does that mean that without Esaki, it's not worth building? This is the dilemma . . .

Here's a series of pictures to show my tentative experiment inspired by The Lurker's comments on pre-shrinking tissue. I used white Asuka for this.

I found an ancient picture frame that was a useful size. I can't remember what was in it - I think it might have been that photogravure portrait of great aunt Eglandina - the portrait that used to scare me so much as a small child. It was that hooked nose and that fierce scowl, mostly, I think . . . what? . . .sorry. Drifted off a bit there. Yes, a picture frame, and absent a Boots spray I resorted to my old spray diffuser - you blow thru it and the venturi effect lifts water up and sprays it. it's a coarse spray but OK for this I think. I attached the tissue to the frame using sellotape. The grain is parallel to the shorter sides of the frame. A few wrinkles, but not too bad. Later, after a good soaking with the spray diffuser, I was disappointed to see that the tissue split upon drying. It wasn't that taut to start with - another indicator of the inferiority of Asuka if you ask me. The picture showing the split tissue was taken with an outside door open and pouring rain outside - it must've been near 100% humid and that's why the tissue looks floppy.

I hand-painted a white rectangle on the shrunk tissue. This was to be opaque, and needed a lot of paint. Then I masked this white patch with a rectangle of draughting film, which had been sprayed with 3M Spray Mount.

[Prosper]

After a couple of days I blasted the whole sheet with black acrylic. My camera doesn't seem able to cope with the expanse of black, but yes, it's black. The final pic taken after removing the tissue from the frame shows that there is a sheen of sorts on the tissue. I suspect from this that it was my scuffing of the tissue with a brush that led to the sandpaper finish of earlier experiments. It's not as even or silky as Esaki IMO but will be okay for a WWII RAF bomber camo finish. Note the wrinkles persisting around the border of the white rectangle - If those don't disappear on covering, that'll be a problem.

Stephen.

[TheLurker]

Evening Stephen,

That didn't look especially successful.

As for fixing the tissue to the frame; I've tried <BluePeterVoice>sticky tape</BPV> in the past and it did not work, the tension was uneven.  If you can afford to waste another sheet of tissue try a <BPV>glue stick</BPV>. You might have to sand the varnish or paint off your frame first though.

[Prosper]

If this approach works, Lurk, I'll buy a canvas stretching frame. I need to understand why the tissue split so easily first, though - and whether it covers the model in a satisfactory manner. All this was supposed to have been discovered by making the test model, but I guess the result was inconclusive.

I found a copy of the Mosquito 'Camouflage & Markings' publication, and in it was another picture of a Mosquito that flew through a fireball (see Malc's Post #113). Also another picture which frankly amazed me - I wouldn't have believed that control could be maintained with the whole wingtip missing.

Mixed results here: the wrinkling evident around the white rectangle largely vanished overnight, but not entirely (see top left corner of the rectangle). I airbrushed the fin flash colours this morning and the masks lifted some of the black paint off when I removed them, so there was some touching-up to do. I had thought this might happen - it's that incompatible match between a mask that sticks firmly enough to prevent underspray, and one that isn't so sticky as to lift paint when it's removed. I have yellow Frog tape, but that's way too sticky for work like this.

After letting the paint settle down for a day or so I'll see whether what I've made can be used to cover the fin.

Stephen.

[dputt7]

Hi Stephen
              I use Yellow Frog Tape as well. But I lay the sticky side on a piece of Plastic or similar and rub the back with a finger then remove the tape.  Repeat several times until it becomes less sticky. I find it is still good enough to give a fine edge to a masked surface but prevents paint removal.

[Prosper]

Thanks Dave. I've tried various things - mostly based on dust - like pressing the tape onto a surface dusted with cornflour - but never got a consistent, repeatable result. I'll try your method.

Stephen.

[Prosper]

As it turned out, I made another Asuka panel for the fin. I didn't like the fin flash colours of my first effort - that despite taking some pains with mixing the colours: they just turned out too - er - colourful. The RAF WWII 'dull red' and 'dull roundel blue' were indeed dull and washed out, according to colour photos, so I took some more pains today to remix my colours. Frankly I think I could have gone further yet - the red in some WWII photos looks almost brown - but of course this is all highly subjective and debatable.

I reverted to my usual method which I call painting on glass - tho' in this case it's painting on MDF. A small panel of tissue stuck onto an MDF board with masking tape and soaked with water spray for pre-shrinking. The MDF board itself has a sheet of 'plastic covering film' stuck to it. This time there was no issue of the tissue splitting as it dried, despite being tugged reasonably taut by the masking tape prior to wetting/shrinking.

Question: doesn't the tissue stick to the backing when sprayed with paint? Answer: no. It can do - it would do if sprayed with a rattlecan, I should think. Work like this, small-scale, using airbrushes in a restrained fashion, causes no attachment.

Stephen.

[Prosper]

After some days elsewhere, I found it difficult to get back to this model. the main reason is illustrated in the attached picture . . . my flying field. Yes, I knew that this was the way that things were headed, right from the end of March this year, but I guess I had some momentum back then that carried the build on. The fact is that it's highly unlikely I'll be able to fly this model before next Spring - the earliest time I could expect a cushioning growth of grass on the field. I flew the test model on hard ground and it survived well but I won't be subjecting this model to such abuse. I have a clutch of models ready for trimming or nearly finished - Sopwith Camel, Leopard Moth, Piper Pacer . . . The corn will be harvested in Sept-Oct I should think, after which the surface will be dirt over the winter, most likely. Perhaps the Camel and Pacer could handle that. But in the meantime my thoughts have veered towards making a model/s which can fly on my own small patch of ground, and that means v. small models or test models of one sort or another.

The last time I flew any model was in March or maybe even Feb - it was the Mosquito test model.

Anyway, I hope to keep the Mosquito covering and detailing at least ticking over. I've started the tissue covering with the easiest bits - tail surfaces. Note to self . . .  don't cover black tissue in low-light conditions . . . The result isn't entirely 'fintastic', but it'll do. I used my usual method of applying the tissue slightly damp (the individual pieces of tissue are lightly pressed between sheets of damp kitchen paper as in the photo), using UHU 'glue pen', which is a wallpaper paste type of glue.

I was alarmed to find how easily the tissue ruptures when using my usual gentle tugging, and stroking with the balls of my thumbs, to smooth out the tissue. See also how the oversize white squares of paint I applied as a base for spraying the blue and red, show up (in some lights) because they have a different sheen to them than the black-only area.

Stephen.