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Old Feb 14, 2012, 10:22 PM
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Bill Smudge's Avatar
United States, KY, Bowling Green
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Doculam- the good- the bad- the ugly.....

That last couple of days I have been covering my balsa Standard J-1 with doculam.

This is what I have learned about this material:

Good

It's inexpensive.

Pre-applied adhesive sticks well.

Very tough, takes a brand new #11 exacto blade to make a clean cut.
Should have very good puncture resistance.

On large flat areas works pretty good, the larger area has enough shrink to it to pull up nice and tight, my fuse and wings came out looking fairly good (BTW this is the first time I have every used a plastic type covering of any type so it was all a new learning experience for me)

After applying heat the stuff is very clear, neat for making windows, portholes, etc.

Reasonably light weight, the covering and two light spray coats of Krylon satin paint only added 16 grams of weight to my plane.

BAD

I found small parts of the plane hard to cover and to get a pretty good wrinkle free surface to the Doculam, I think there is not enough shrink to the material to pull out the wrinkles.

When applying before shrinking you must get the stuff as tight and wrinkle free as possible to get a presentable result.

Be careful and don't make the bonehead error I made--- when you heat this stuff the adhesive turns clear, so clear in fact I started covering over the same surface on the horz tab before I realized I had the surface turned the wrong way......

UGLY

My wingtips look like rap, I have promised myself the next balsa plane I build I'm going to beg, borrow, or steal some lightweight balsa blocks and make solid wingtips

CONCLUSION

I would use it again, but probably would like a mix of covering materials. Something that works well on small areas and the non-flat stuff like wingtips would be great.

Old info I'm sure, but may help somebody.


Bill

Heres my end result, may have a little touch-up here and there before assembly:
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Old Feb 14, 2012, 11:22 PM
This is kid stuff.
Mazzepa1's Avatar
USA, AR, Harrison
Joined Aug 2010
902 Posts
I've not tried Doculam, but am interested in finding a covering that takes paint well so I've been reading all I could find about it.

Your experience confirms my assessment from study. I wish there was something out there just like Doculam that would shrink a little more.

I hope your J-1 flies well.
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Old Feb 15, 2012, 06:57 AM
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planeman's Avatar
Atlanta, GA USA
Joined Sep 2001
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Here's a little hint about covering wingtips and wheel pants (compound curves) with heat-shrinkable coverings.

Pull the covering strongly in one direction over the curved surface with one hand while applying the heat with the other hand. The object is to prevent the shrinking in one direction while enabling it in the other. This allows the shrinkage to take place in one direction only thereby conforming the covering to the compound curve.

Planeman
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Old Feb 15, 2012, 08:07 AM
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Albuquerque, NM USA
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One of the problems with shrinking doculam is the strength.

Example: Wing has a small loose spot near a corner. Heat and shrink. Now there's another loose spot on another area. Heat and shrink. Original is back again. repeat. Pretty soon the wing is a pretzel

The doculam is probably as strong as monocote when shrinking it and will pull structures out of shape easily. As stated, be precise when sticking it down and get it as even as possible before shrinking.

Because it is clear it is difficult to see some wrinkles. Inspect carefully before painting.

Seams show up dramatically after painting, especially with lighter colors. Be careful when you plan for them.

I do love doculam for the ability to accept paint, especially latex house paint. But, I dislike it a lot because of how hard it is to get all the wrinkles out.

Last. It is CHEAP!! Do not be afraid to tear off covering that has been applied incorrectly. Better to have three (or four) attempts and get it right than have one that comes out ugly.

charlie
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Old Feb 15, 2012, 10:41 AM
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Canada
Joined Nov 2000
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Dunno.. that covering job, in the photos at least, looks acceptable.
In contrast there are more than few areas that would have benefited from a flat sanding.. which is seemingly more apparent than a few unfortunate wrinkles.
Still, No model is ever perfect, as I've finally come to realise/accept and I've been 'trying' for one for 50 years...
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Old Feb 15, 2012, 11:20 AM
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glewis's Avatar
USA, FL, Tampa
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The 'chase the wrinkle' thing can be very frustrating. I've found that heat control is your friend. Turn the iron heat up just enough to start the shrink and leave it there.
Resist the temptation of turning up the heat and starting the 'chase the wrinkle' cycle. With lower heat you can use the iron to 'scoot' the covering around a bit without shrinking it more. If it just won't smooth out then strip and recover the stubborn spot.
And BTW, let the iron cool and remove the adhesive off the shoe with acetone. Guess how I know....

Glenn
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Old Feb 15, 2012, 12:09 PM
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Doculam will take paint if properly cleaned with acetone or other. Masking tape with any tackiness will lift paint off. My main dislike is patching painted doculam or any film covering that has been painted. Patches tend to look like patches, they don't "disappear" as with unpainted thin adhesive-backed coverings. Model tends to look "aged" after a few of patches from wear and tear.
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Old Feb 15, 2012, 01:23 PM
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Bill Smudge's Avatar
United States, KY, Bowling Green
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All great info guys!!

One thing is for certain...it's strong. I've been manhandleing my J-1 all day long starting to mount the wing surfaces, wheels, etc. and the good 'ol stuff doesn't have a single hole poked through it


Bill
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Old Feb 15, 2012, 01:58 PM
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glewis's Avatar
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And it stays tight when the model sits in the sun unlike solite and to some degree parklite and Ultracote.
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Old Feb 15, 2012, 08:40 PM
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E, if you use latex house paint it won't lift, even with duct tape. BUT, you must let it fully cure, 3 days or so.
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Old Feb 15, 2012, 08:47 PM
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New Boston, Texas, United States
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Charlie,

I have to disagree. On my Peck Zero, I used some low tack masking tape to hold the canopy down while the canopy glue dried and it peeled off big sheets of the paint. This paint had been on for at least 2 weeks and I treated the film to vinegar and cleaned with alcohol before painting. I have sworn off Doculam for the near future while I try some different methods.

Jim
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Old Feb 15, 2012, 09:50 PM
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Interesting.

I've not been able to separate latex paint from doculam once cured. I've even cut it, torn it, crumpled it in my hand, and the paint doesn't come off.
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Old Feb 15, 2012, 10:28 PM
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Bill Smudge's Avatar
United States, KY, Bowling Green
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Seems that there are some broadly varying experiences with paint and Doculam.

I used plain old Krylon spray on my model yesterday, two very light and thin coats, looks to be pretty well stuck to the Doculam. I have not tried any masking tape and pulling on the finish though. I did rub the Doculam down with vinegar in prep for painting, FWIW.

Probably the best way to approach the material is to do some test panels with the paint you plan on using, and verify it sticks well to the stuff. I know it would be quite painful to have a nice covering job mucked up by having the paint come away from the covering....



Bill
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Old Feb 16, 2012, 01:45 AM
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ben199's Avatar
New Zealand
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857 Posts
Hi Bill,
I have had some sucess with painting doculam and the only problems I have had was from using tape over freshly painted surfaces.
You do have to take your time when applying the doculam to avoid wrinklles or like me just live with it
On my latest build a L-4 grasshopper I decided to cover the doculam with tissue to give a canvas finish, it worked well and made painting it a breeze
I also used doculam for the windows.
-Reuben
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Old Feb 16, 2012, 03:26 AM
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Staffs, UK
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It's also worth noting that there are many different general purpose laminating films that people have taken to calling "Doculam" (a bit like all vacuum cleaners, whatever the make, used to get called "Hoovers" ). They're available in several different weights/thicknesss and surface finishes. It's a fair bet that some of them take paint better than others.

Steve
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