dope and tissue covering

[Robert Leadbeater]

hi all,
nearly building my simplex which is my first balsa build and now im looking at how to finish it. ive already sanded the whole plane with 220 grit sandpaper and ive already got some dope but i need some tissue is this just ordinary tissue or is it specialist stuff? i don't want it coloured too much ill just paint a bit with humbrol enamel.another thing would it be best to glue the tail on after or before covering?

[Alistair Taylor]

Robert

you can use ordinary stuff from stationers (and it's easier to get hold of), but the "proper" stuff, is (I believe) stronger and lighter.

I got good results with the tissue sold in muticoloured rolls from staples. This tissue does have obvious glossy and matt sides to it (stick the matt side down!), and you get a rainbow of colours all in one roll.

AlistairT

[leigh hodson]

how do you get it to stick without wrinkles on a sheeted surface? never done tissue over sheeting only open structure.

[Alistair Taylor]

Spot on David - I do pretty much the same, wetting the tissue with water, but applying it with cellulose thinners onto a pre-doped surface. It sticks tighter than a limpet then, and usually tightens up nicely.

In researching the application of tissue to balsa I did read somewhere that after wetting the tissue you should crumple it up into a ball and squeeze it to get rid of excess water.

In my experience (with the staples tissue), doing this leaves you with a ball of scrunched up tissue that is impossible to unfurl into anything resembling a sheet!

Robert - for open structures (e.g. ribbed wings or framework tailplanes) you can use tissue paste to stick the tissue to the structure, instead of dope. This is a lot less smelly (so you could do it indoors), and can help stick tissue to undercambered wing surfaces. Dope tries to shrink as it sticks, so the tissue can pull away before it has firmly stuck.

It's a good idea to pin wings/tailplanes down to dry after doping to prevent warps.

I'm recommend practising on some balsa scraps to work out the technique that suits you best, and to see just how much tissue shrinks.

NB - You can reduce final shrinkage by "pre-shrinking" - i.e. wetting the tissue and allowing it to dry once before using it.

AlistairT

[Myron Beaumont]

Question ?
Where can you get the modern equivalent of proper tissue ( ie Japonese ) ?
I always stuck it down dry with dope as the adhesive 'cos you can taughten it as you go & if its not quite tight enough ,just stretch it after wetting with more dope Then soak with water & watch it shrink before the finishing coats .It goes really saggy when you've wet it .'Don't worry .You'll be amazed .By the way I never apply nylon wet .It's synthetic & doesn't shrink Let the cellulose dope do the shrinking .

[Bob Howard]

As regards the tissue, a good model shop will stock both heavyweight and lightweight. If you are covering a sheeted surface, it is as well to stick with the lightweight.

I usually prefer to cover with coloured tissue - it is easier to see what you are doing, especially when you are rubbing it down.

Sandpaper the wood down carefully, then pre-treat it first with dope. Allow it to dry fo a few days before rubbing it down again to remove any grain raised by the dope. You can mix a little talcum powder with the dope to act as a grain filler.

Cut the tissue oversize, spray it with water (I use an old "Mr. Muscle" trigger spray) and leave to soak for a few minutes.

Lay the tissue on the surface, then apply the thinned dope with a large soft brush, working outwards from the middle. The dope will dry with a white bloom caused by the water, but this will diappear with the next coat of dope. You will need several coats, with a light rubbing down between each coat.

Finally, remember that dope is not fuel proof. I have been experimenting with using Clearcoat instead of dope. It seems to work Ok, and is fuel-resistant. It also accepts Solarlac paint, which is probably more fuel resistant than enamels.

[Robert Leadbeater]

ok thanks. another question is there anything that isn't as intoxicating as dope.

[Alistair Taylor]

Wine is slightly less intoxicating, I find a good Shiraz is best. Whisky is right up there with Dope, go for the single malts and sip in order to appreciate the intricate flavours of malt and burnt peat. Gin and tonic is much more refreshing, but the intoxication creeps up on you. Pimms and lemonade is probably best at the moment, what with Wimbledon and all that.

but none of these

hic

Sssshrink.

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tishhhhyou

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Blesh you

AListairT

[Myron Beaumont]

Dear Alist air Hic ! Does "shiraz" come in plastic bottles to make cockpits from? & can you buy it in cases ? If so is it in the right colours to hide away the pilot who isn't inside (re-toy pilots thread} ?

[Myron Beaumont]

By the way. who shrinks his toilet paper before they use it & if so Why ? Use it dry and shrink it once in place .It works, I should know <'cos in common with artistic creative active hard living people who have resorted to Solartex I have suffered from haemhorroids ie piles (never could spell that word) !

[FlyinBrian]

If you have not used tissue and dope before then think again about this form of covering. It is messy, smelly easily damaged (fortunately easily repaired usually)

Consider one of the lighter films such as Solarfilm Lite.

If you must use tissue then thin the dope at least 50% with cellulose thinner. wet the tisse with a spray if it is lightweight or by dipping in a bowl of H20 if it is heavyweight, dry most of the water out of the tissue by squeezing or mopping with a kitchen towel.

pre dope the framework and sand off the resulting raised grain once the dope has dried.

Cut tissue with a good overlap (min 1") to shape and size then lay the damp tissue onto the framework, pull it reasonably tight, the dampness will help it stay in place, then brush the thinned dope throuh the tissue ( but only where there is wood unbderneath) making sure it gets through into the previously doped wood. Let it dry! then trim the excess off, this is easiest to do with fine sandpaper on a sanding block. Do the other side in the same fashion making sure you overlap at all corners and edges.

Now, if this is an open structured wing for instance, give each side a coat of dope, you need to get the tissue wet but do not need to flood it with dope or you will get pools of dope forming inside the wing.

Let it dry so that it is no longer tacky then pin or weight it down on a flat surface - this is important as it will warp if you dont.

Once the first coat is dry you can repeat the doping as above until you have filled all the grain in the tissue and it is airproof.

Takes longer to do than say I am afraid so perhaps you need to re read my opening paragraph