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Tissue wrinkles on doculam question


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I have covered many many models with tissue so that bit is fine, but with  this Galahad I am building I have pushed into very new territory and covered it with Doculam!  That went on very well but the tissue I am laying on top has developed wrinkles and stretch marks that wont budge.  I have tried wet and dry and have used dope and thinners to adhere it, but it just wont stay flat and tight.

 

I watched a very good video and he used water based polyurethan, maybe a Poly C type which I have used.  Is this my issue?  Should I avoid dope as a the adhesive?  As soon as I sprayed the tissue with water it bubbled and wrinkled of course, well it would as it is laid over a plastic film!

 

How does one achieve a beautiful surface please?

 

David

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Is the problem possibly the tissue itself?

 

I bought a few sheets at one of the Old Warden events last year, for use over the sheeted surfaces on a scale model. I am attaching it using traditional thinned dope.

 

Normally on brushing through the tissue, it goes pretty much transparent and softens sufficiently to comply with reasonably curved surfaces, but in this case it seems that the tissue is loathe to absorb the thinned dope, resulting in both wrinkles and in some areas failure to attach to the underlying surface. These show up as white areas once dry.
 

In the worst areas I sanded it back and reapplied using some tissue donated by a friend using the same technique, and it was much better.

 

In other areas I was able to rescue the panel by brushing on neat cellulose thinners.

 

Brian.

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2 minutes ago, RottenRow said:

Is the problem possibly the tissue itself?

 

I bought a few sheets at one of the Old Warden events last year, for use over the sheeted surfaces on a scale model. I am attaching it using traditional thinned dope.

 

Normally on brushing through the tissue, it goes pretty much transparent and softens sufficiently to comply with reasonably curved surfaces, but in this case it seems that the tissue is loathe to absorb the thinned dope, resulting in both wrinkles and in some areas failure to attach to the underlying surface. These show up as white areas once dry.
 

In the worst areas I sanded it back and reapplied using some tissue donated by a friend using the same technique, and it was much better.

 

In other areas I was able to rescue the panel by brushing on neat cellulose thinners.

 

Brian.

Brian thanks.  The tissue is white heavyweight (albeit from a craft shop not a model shop as the cost for the same stuff was about half).  My next tissue will be from Mike at Freeflight Supplies, at least then its a known quantity.

 

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Done tissue or that ladies unmentionables fabric over doculam on several vintagey type models without problem. I lay the wet tissue/fabric over the airframe, ease out the wrinkles and coat with Minwax Polycrylic (other water based varnishes are available). It seems that the wet tissue/fabric has enough time to tauten during drying. Jon, you're right, doculam and the job's a good un, but not the most attractive. Doculam will take paint (use matt doculam and a light coat of car plastic bumper primer first) but on an old timer the doculam renders the structure air tight and the tissue/fabric looks good without needing endless coats of dope/wbv to seal it.

 

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2 hours ago, David perry 1 said:

its doculam.

 

yea i know. I dont understand why you are covering the model in a perfectly satisfactory covering material only to go over it with tissue. If you want a tissue covered model cover it in tissue and be done with it. 

 

I cant see any reason to cover the model twice with different materials 

 

DH2

 

If that is the reason it just makes no sense to me at all. If its an old timer model and you want an old timer finish then do an old timer finish in the first place. 

Edited by Jon H
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                 The two layer covering is done for strength/paint reasons, tissue is easy to puncture and goes brittle over time. Normal Doculam is smooth and clear and does not take paint well even when scoured so tissue is put on top.

However Matt or what is called Soft touch Doculam can be used and takes paint well.  See feature on "working with Doculam on vintagemodelcompany.com site.

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This model is covered with laminating film, then tissue covered. It worked very well, no wrinkling.

 

However I recently tried the same approach on another model, there were wrinkles. I have come to the conclusion, I tried recycled tissue, the staple is much shorter than old, traditional tissue, this seems to cause the wrinkles. The problem is there just using tissue over balsa, a case that saving the planet comes at a cost.

 

 

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I discovered that using water based dope worked the best when tissueing over 5micron Mylar, no wrinkles no messing about brushing them out just tease it out around the edge. Applying tissue over a lightweight substrate like Mylar is actually lighter than tissue alone because the dope doesn't pool inside the tissue and it's airproof needing no more dope than one coat. Other advantages of this two stage process are, it's puncture resistant and more rigid than plastic film alone.

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2 hours ago, Jon H said:

 

yea i know. I dont understand why you are covering the model in a perfectly satisfactory covering material only to go over it with tissue. If you want a tissue covered model cover it in tissue and be done with it. 

 

I cant see any reason to cover the model twice with different materials 

 

DH2

 

If that is the reason it just makes no sense to me at all. If its an old timer model and you want an old timer finish then do an old timer finish in the first place. 

John . Its a technique used for some time now especially for scale and vintage models. The tissuue effect is desired on vintage but is not very punture proof and doculam give added punture resistance at little weight penalty. The tissue also takes paint very well. 

I like the tissue effect on open framed models but preffer to use matt laminating film . Really strong , takes paint and cost pennies compared to our covering films. My 60 inch Elf Bipe cost well under a fiver to cover .

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Engine doctor...Elf is beautiful...must build one soon.   Is it only film and paint, no tissue at all??

 

Jon, the doculam is cheap as chips - £17 for 160m of the stuff.  I have put tissue over it because i like the look of tissue but it is very fragile as you know and so easily punctured.   I have gone right off plastic films in recent years, it just looks so awful to my eyes now.  I was lucky enough to have lived and modelled in a time when I saw solarfilm invented and marketed, and i have seen solarfilm disappear.    I loved solarfilm and will be forever grateful for its invention, but todays films leave me cold and I have changed anyway, I now only want to use silk, nylon and tissue.  HOWEVER, as I sat thinking these things through and having once eschewed doculam, I thought, hang on...Im using more chemistry in dope and thinners than I can shake a stick at, why not try doculam.  So I have. And it's impressive because of the strength it imparts, and it's dirt cheap.  Cheaper than dope!  Next stop is water based polyurethane, which I believe is fuel proof.  So doculam, coloured tissue, poly c.   Jobs a good un.

Edited by David perry 1
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3 hours ago, J D 8 - Moderator said:

See feature on "working with Doculam on vintagemodelcompany.com site.

I couldn't find that info on the Vintage Model Co site - a link to it would be handy.   Also other useful links to working with Doculam.   

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still sounds like a very backwards way of covering a model. For vintage models like this i wouldnt like to see a film finish either, but i would probably just use a solartex equivalent on a bigun or tissue on a small one. Is tissue fragile? yea, but thats the price of admittance so im not really too worried about it. 

 

When i eventually build my ballerina it will be a simple tissue job. 

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11 hours ago, Jon H said:

still sounds like a very backwards way of covering a model. For vintage models like this i wouldnt like to see a film finish either, but i would probably just use a solartex equivalent on a bigun or tissue on a small one. Is tissue fragile? yea, but thats the price of admittance so im not really too worried about it. 

 

When i eventually build my ballerina it will be a simple tissue job. 

 

Each to his own.

 

My first model aircraft were covered in doped tissue over sixty years ago. I distinctly remember having to repair the covering after virtually every (free flight) flying session. At 76, life is too short for that game of soldiers so I've covered my Uncle Ivor's 76 year-old Outlaw in doculam and have attached tissue over the top using water based matt varish which I bought at a builders' merchants. You have more time to ease out any wrinkles using this stuff than you have with dope.

A Work in Progress.JPEG

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17 hours ago, Jon H said:

 

yea i know. I dont understand why you are covering the model in a perfectly satisfactory covering material only to go over it with tissue. If you want a tissue covered model cover it in tissue and be done with it. 

 

I cant see any reason to cover the model twice with different materials 

 

DH2

 

If that is the reason it just makes no sense to me at all. If its an old timer model and you want an old timer finish then do an old timer finish in the first place. 

It's puncture resistant, lighter, much stronger and provides an excellent substrate for water-based polyurethane finishes.

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16 hours ago, David perry 1 said:

Engine doctor...Elf is beautiful...must build one soon.   Is it only film and paint, no tissue at all??

 

Jon, the doculam is cheap as chips - £17 for 160m of the stuff.  I have put tissue over it because i like the look of tissue but it is very fragile as you know and so easily punctured.   I have gone right off plastic films in recent years, it just looks so awful to my eyes now.  I was lucky enough to have lived and modelled in a time when I saw solarfilm invented and marketed, and i have seen solarfilm disappear.    I loved solarfilm and will be forever grateful for its invention, but todays films leave me cold and I have changed anyway, I now only want to use silk, nylon and tissue.  HOWEVER, as I sat thinking these things through and having once eschewed doculam, I thought, hang on...Im using more chemistry in dope and thinners than I can shake a stick at, why not try doculam.  So I have. And it's impressive because of the strength it imparts, and it's dirt cheap.  Cheaper than dope!  Next stop is water based polyurethane, which I believe is fuel proof.  So doculam, coloured tissue, poly c.   Jobs a good un.

Hi David. Just 75 micron matt laminating  film NO tissue. Its also iron on like traditional film with its own heat activated adhesive ( be sure to get the Hot type and not the self adhesive type ) . Application is similar but needs tidy tacking as it doesnt shrink quite as much as our covering films. For final shrinking a lot more heat is needed but its VERY hard to burn through.  I use covering iron turned right up then a hot air gun (modeling type ) for final shrinking. Overlaps are pretty permanent and wont come apart without heat.

I found 2 x 100 meter rolls on ebay for just under £30 enough for a load of models ! 

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6 hours ago, Engine Doctor said:

Hi David. Just 75 micron matt laminating  film NO tissue. Its also iron on like traditional film with its own heat activated adhesive ( be sure to get the Hot type and not the self adhesive type ) . Application is similar but needs tidy tacking as it doesnt shrink quite as much as our covering films. For final shrinking a lot more heat is needed but its VERY hard to burn through.  I use covering iron turned right up then a hot air gun (modeling type ) for final shrinking. Overlaps are pretty permanent and wont come apart without heat.

I found 2 x 100 meter rolls on ebay for just under £30 enough for a load of models ! 

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 

 

 

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