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Tissue wrinkles on doculam question


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17 hours ago, David perry 1 said:

Nice.  Ive used 39Mu for the Gallahad but I have added tissue as the film is fully clear.  Ive messed the tissue up a bit and it has also turned out with a lot of white blooms for reasons I do not know.   As I always say though, it might be cr*p but it's MY cr*p.  And at 100 yds in the sky it will look perfect 

 

 

I have some 38 micron matt laminateing film it looks very similar to the thicker version although it seems more elastic once shrunk. I have not covered a model in it yet just a couple of test frames. The lighter film I bought was only 30cm wide so is limited to small sized models. 

As you say when its flying no one can tell the difference . 

As Andy says another coat of thinned dope will remove the bloom provided you choose a day with low humidity.

Back when NitroCellulose paint was widely used on cars , those of us without the luxury of a spray booth often had patches of bloom on the finish coat  if the weather was cold and humid. The cure was either to use Anti Bloom or Retarder thinners. As that was considerably more expensive  the alternative was to take a chance and if it bloomed just leave to dry and give a quick flat with 1200 grit then a wet coat of thinned paint when it was a bit warmer. The up side was that do8ng the final flat and a wet coat gave a superior finish. 

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Using laminating film, is generally not a problem. Unless, that is, you are going over Depron or foam board. Then the issue is the high heat, I use to shrink, is not compatible, with the polystyrene.

 

The only problem I have had recently is with "Tissue", in this case of recycled, green tissue, my results looked like your photo. It is my intention to dump these sheets, as not suitable for my needs.

 

I will be purchasing something claiming to be Modelspan, or similar. If my other stocks are questionable, I have no MS near me anymore, so it is online purchases. I suspect it was a Amazon purchase that is my resent issue, although I cannot be certain. My purchase will be either a specialist FF garage type seller, or perhaps Leeds, now that Webbies have closed.

 

I also tend now to use WBV, either Ronseal Hardglaze, Wickes WMV. I do tins of MHG of dope

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Just wondering if the wrinkles are caused by not allowing the tissue to soak long enough ?  If its still expanding then wrinkles will appear and as its laid over doculam and the dope will dry quickest preventing the wrinkle from shrinking out ?  There surely  must be some aficionados on tissue application on here ? 

Mike Smith, a member of our club  has been Free Flight Scale Champ many times see his tips here. He doesnt have section about covering over doculam but does silk over tissue etc and worth a read . His models are museum quality and he just lets them fly free flight !

Edited by Engine Doctor
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In my case I believe it is the short staple length that is the result of using recycled paper. There is also potentially an issue in that with some virgin tissues, the composition/source of the feed, is carefully controlled, particularly in the case of Japanese tissue (the type that is suggested contains Bamboo). Where the recycled green material. is what what it is, a mixture of, who knows what.

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3 hours ago, J D 8 - Moderator said:

  How about EZE tissue from Deluxe materials.

Eze tissue works very well over laminating film, applied as per the Deluxe Materials instructions. That means soaking the tissue as cut slightly oversize with thinned water:Eze Dope 95:5,,  until wetted out then rolling in a ball and squeezing out the excess fluid. I like to use their tissue paste around the edges before applying the damp tissue and smoothing into place with a wetted piece of foam rubber, fingers and thumbs. Once dry a couple of coats of 70:30  water:Eze Dope to finish off.

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I tried recycling tissue as well, coloured stuff from Christmas.  Total failure. It stretched waaayyy too much and I had to peel it off. I’ve bought colours now from Mike Woodhouse

 

the application of thinners has reduced the bloom as stated so thanks for that. This is the last time I’ll use dope this way I think, I’ll use water based varnish in the future. I gather this is fuel proof too.  I will have to fuel proof my Galahad after all this.  It’s a drawn out procedure. It’s also rather good fun 

 

Ive managed to get to a level of proficiency where I no longer have tissue wrinkles though, so I’m pleased with that. The trick is lots of water and wait, wait and wait. When absorbed then stretch the tissue and brush out bubbles and wrinkles. Works well.  I could do this thirty years ago…funny what we forget!  
 

 

Mind you, bending the wire undercarriage has defeated me. I’ve heated the wire to bend it as I always did but have snapped two pieces at the bends.  Never in nearly fifty years modelling have I snapped piano wire like this. I’m almost convinced they’ve changed the composition of piano wire !!  I’m at the stage where just buying an undercarriage seems the best bet but that’s defeat ha ha

 

 

overall this model has been a great ‘comeback’ model and I can’t wait to fly it. 

Edited by David perry 1
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Unless you get your piano wire from a known supplier - like the K&B Metals stand - there is a risk that the currently available piano wire is indeed very different to that you used in the past. It is very often brittle and can break easily if you look sideways at it,

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6 hours ago, David perry 1 said:

Mind you, bending the wire undercarriage has defeated me. I’ve heated the wire to bend it as I always did but have snapped two pieces at the bends.  Never in nearly fifty years modelling have I snapped piano wire like this. I’m almost convinced they’ve changed the composition of piano wire !!  I’m at the stage where just buying an undercarriage seems the best bet but that’s defeat ha ha

 

David, after heating the piano wire bend area to 'cherry red' and letting it air cool it should bend easily but is no longer springy.

 

Next step is to heat it to cherry red and dunk it in water, now it is very hard and brittle.

 

Last step is to gently heat the bends to  a dark blue colour to temper the piano wire.

 

It won't be as precise as the original manufacturer's temperature controlled environment but it's not too bad

 

Here is a guide that works well for me

Music Wire Heat Treating.pdf

Edited by Christopher Wolfe
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For wetting tissue over Doculam, a re-purposed scent sprayer works nicely to locally spritz the already dampened tissue with water if it shows signs of drying out.

 

I can still purchase amyl acetate here in Australia, it smells like bananas and just a light brushful should remove all blushing, otherwise just give another coat of dope but mix in about 50% dope thinners.

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11 hours ago, David perry 1 said:

 

Mind you, bending the wire undercarriage has defeated me. I’ve heated the wire to bend it as I always did but have snapped two pieces at the bends.  Never in nearly fifty years modelling have I snapped piano wire like this. I’m almost convinced they’ve changed the composition of piano wire !!  I’m at the stage where just buying an undercarriage seems the best bet but that’s defeat ha ha

 

 

overall this model has been a great ‘comeback’ model and I can’t wait to fly it. 

Hi . Piano wire is not what it used to be and varies greatly . Some are lucky and get proper Piano wire that bends and is springy. There is probably a lot made from Chineseium and its brittle . Once heated to cherry red it often becomes brittle . Chris wolfes post re heating ,bending and re-tempering works on proper piano wire if you can get it but some stuff is just rubbish . Good luck .

Edited by Engine Doctor
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Back on the subject of blooming, there is a product you can get from Halfords called leveller spray which is just a can of high quality thinners, the purpose of which it to level out any orange peel effect of sprayed paint. It just redissolves the surface of the newly sprayed paint to allow it to relax to a more smooth finish. This smells just like the "amyl acetate" that Christopher describes and it may well be worth keeping a can of it about the workshop.

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19 hours ago, Engine Doctor said:

Hi . Piano wire is not what it used to be and varies greatly . Some are lucky and get proper Piano wire that bends and is springy.

Maybe I am lucky because I still have a local hobby shop and they stock K&S music/piano wire and tubing. https://ksmetals.com/collections/music-wire?srsltid=AfmBOoqq9MCVh-Ou80Xzws1BjRXac8QmHUZ5ihF8XsNN4YyG21QrLm9z

 

Never had a problem using it so I hope that it is also available in the UK 🙃

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