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Old May 18, 2014, 01:59 PM
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Philadelphia, PA
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Packing Tape Covering Jobs...Best Practices?

Hello fellow scratchbuilders!

I'm at that critical point in a project where it is time to pick/design a paint scheme! Normally, I finish sand the plane (bare DTF or MPF) and apply lightweight spackling to any dents or dings. Then I coat the plane in a primer mixture (Freddie B's Secret Sauce - a mixture of minwax poly, spackle, talc, and water). Once this is sanded down, the airframe is ready for the final paint job.

For this build, I have decided to things a little different and attempt a packing tape paint job! I've got an order of 2mil thick colored packing tape on the way. I would like to know the best way to prepare the bare foam for the best adhesion once the tape is applied. So far, I have sanded and applied lightweight spackle to dents and ugly glue joints. Once I have completed the finish sanding, what do I need to do to prepare for the tape?

I was thinking of dusting the airframe with a light coat of 3M super 77 spray adhesive and/or airbrushing on a light coat of minwax clear polycrylic. Are these steps unnecessary for a tape finish or will they improve adhesion? My primary concern is sanding dust. Once the tape is applied, I plan on shrinking it with a heat gun.

Any experiences (good or bad) anyone has had with this would be extremely helpful. I am really looking forward to experimenting with packing tape finishes! Thank you in advance - I will definitely post pics of the result!
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Old May 18, 2014, 10:30 PM
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The packing tape will stick to just about anything - you don't need to do anything special to prep.

I'd be a little wary of using a Minwax base - the oil in the Minwax can potentially reduce the adhesion on the tape.

Waxed paper makes it easy to cut out decals and patterns with the colored tape - be sure to leave a little edge of waxed paper to peel the rest of it off.

I've never tried a heat gun on the colored tape, but if you use a credit card to firmly tack down the tape you shouldn't have any problems with getting it to stick closely. If there are bubbles in the tape, just pierce them with a blade and they'll generally lay flat.

The only problem with packing tape finishes is that you rapidly end up with large collections of packing tape rolls in all sorts of colors...
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Old May 18, 2014, 11:19 PM
Fremont, CA
United States, CA, Fremont
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Wombat, I like your idea of using tape for decals. But the colored tape that I have is semi-transparent and you can see what's behind it.
Are there opaque colored tapes too?
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Old May 19, 2014, 04:11 AM
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A coat of 3M 77 is a good idea, and a thin coat of UHU POR is probably slightly better. some types of foam, like EPP, will shrug off any coating without it.

Packing tape may stick to almost anything, but it doesn't like to stay stuck on bare foam. Flexing will gradually work it loose, and it sounds awful. I've heard of using a steam iron or covering iron, but you have to be very careful with heat of any kind near foam.

To improve opacity with packing tape, you could try a "base coat" of white or grey tape, depending on the top coat colour. You can get some interesting colour effects combining colours in this way.

Duct tape is usually available in colours, sticks a lot better than packing tape, and is opaque, but it's heavy. PVC tape (electrical tape) is often available in 2in width, and tends to be pretty opaque, but the adhesive is worthless, and CA or contact adhesive will be required to keep the corners down.

As always, when using a new material or technique, try a sample on some scrap before committing to your final method.
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Old May 19, 2014, 05:10 AM
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Yeah, no matter how tight you get the packing tape, if you fly in hot, sunny weather, eventually it expands and bubbles slightly. That doesn't bother me too much. I'd rather have the foam-board without paper and thoroughly covered in packing tape (totally sealed at all edges). It weather-proofs your plane and is no heavier than foam with paper (that paper is around 45% of the weight for DTF ). It also adds quite a bit of structural rigidity if done right.
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Old May 22, 2014, 12:01 PM
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I use a dusting of spray glue. Polycrylic reduces adhesion so if you poly then cover (i do,,,), you want a dusting of spray adhesive Let it tack and then tape.
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Old May 22, 2014, 06:14 PM
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Some of Ken's Taping Tips

Maybe I can contribute in this area since my FBs seem to think my tape jobs are outstanding.
Here a few tips that I have discovered, though probably not new, just new to me.

1. Finish sand the surface to be taped - Leaving rough surfaces will show through the tape surface. No need to worry about the fine pores, just a smooth surface. This will give the possibility of a paint like finish. Even if you can't sand some foam that is left flat, it still gives a much nicer finish over the bare foam and provides and element of protection.

2. Use a Monokote (or similar tool) iron - Packing tape does not shrink very much, but when you apply heat it does expand and stretch. Heating the tape allows you to pull around compound curves and it shrinks back when it cools. It is kind of a reverse process to the iron on films. It works great though. I run mine at a midway heat setting. Just hot enough to sheen the foam if moved slowly. but not stick.

3. Trim seams away from corners - Packing tape does not like to stay folded. So on flat surfaces like edges of tail surfaces and all such others, the first side should fold over and trim and likewise for the second side on the back of the trailing edge. Allowing the second side to finish without a fold at the edge works great for fuselages.

4. Taping works over painted finishes - This is really great if you want to get some painted graphics and attain a high shine. For this I use acrylic paints, and then iron on clear packing tape. I use the cheap $1 rolls of clear (Duck brand), as it is the thinnest

5. Uniform overlap - Paying attention to uniformity in overlap will help with colored packing tapes finished appearance. If you don't then the taping job starts to reveal that you worked a bit hastily and detracts from the finish. Clear packing tape once ironed down makes the seams virtually disappear.

6. Tape details separate - Taping some details separately from one another makes taping a lot easier. Such as the vertical fins on my Prime Jet 8-32 Ultra. It was much harder to do the wing and fins after they were assembled. On the second one I did them separate and was much happier with the results, and it was much less work as well.

7. Patience is the Key - Take you time and do not be in a hurry. You have gone to a lot of trouble to build a nice model and you are about to finish . It may take as much time to finish as to build it in the first place. Working when you have time and no distractions can be very peaceful and rewarding. When the opposite is true, you will be stressed and hurried, and a hurried job always looks hurried.

Ken

Here are some samples

This model was painted entirely and then covered with clear tape. Model was originally pink foam.


This model was a lot easier to finish by leaving the fins off until the wing and fuselage was finished


This is an example of colored and clear tape and painted graphics. The crosses were Shapie on a bare foam field.
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Old May 22, 2014, 11:10 PM
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Awesome guys! Thanks to all for the great information.

Ken - those tape jobs are gorgeous - exactly what I am looking to achieve!
When executing the trim details over the base tape coat, do you cut first and then apply -- or apply and then cut away what you don't want? (ex - your PJ8 build)

My tape is on the way and I've got the airframe ready...can't wait to get started!!!
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Old May 23, 2014, 05:10 AM
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In general, I do not do a tape base coat, but put down the colors in order of dark to light. Dark color tapes tend to show through light ones. So get the lighter colors down first, or you will get funky colors showing on the tape overlaps. Another tip to add to the list.

In most cases I do try to trim then apply. However, trimming afterward is needed and preferred in some cases. Laying your tape on a clean surface and pre trimming works well for decal like details. Then you can lift it and apply.

One a the most critical rules for taping is the use of a sharp knife. The adhesive tends to collect on the blade and needs periodic cleaning. Another tip for the list.

Ken
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Old May 23, 2014, 11:45 AM
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Isn't it also appropriate to wipe down the foam surface after sanding with a tack cloth and or rubbing alcohol to remove dust, dirt and fingerprint oils? And then optimally you'd want to work with gloves on to not foul the adhesive.

For pre-trimming tape for stripes and chevrons and things I've stuck packing tape to clean wax paper, trimmed it to shape and then peeled it.
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Old May 23, 2014, 12:25 PM
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Quote:
Originally Posted by BrownEyedFool View Post
Isn't it also appropriate to wipe down the foam surface after sanding with a tack cloth and or rubbing alcohol to remove dust, dirt and fingerprint oils? And then optimally you'd want to work with gloves on to not foul the adhesive...
Somethings I do without thinking!

Ken
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Old May 30, 2014, 01:00 PM
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…some progress...

Hello All,

Thanks to all of your tips and suggestions, I am on my way to completing my first 'packing tape covering job"! So far, I am very happy with the results. I'm learning as I go. One of the best things about the tape method is if I mess it up too much, I can just pull it up and start fresh.

The tape is very thin (2mil) so color order is very important. As Ken suggested, applying color/trim light to dark is a must. It just forces a bit of pre-planning before tape application - similar to airbrushing.

As for complex shapes - with a sharp blade and a steady hand, it is possible to cut through a single layer of tape. So, trim can be applied, cut, and excess tape can be weeded away. (Still getting this process down)

As for surface prep, I sanded the entire airframe, filled dents with lightweight spackle, and then dusted the entire surface with 3M77 spray adhesive. Once tape was applied, I hit all edges and corners with a small craft iron on low heat (I picked up the craft iron from Michael's craft store). Then I shrank the tape covering a bit with a hot air gun on "hi" but moving very quickly. **CAUTION**Too long in one place will melt the tape and destroy the foam underneath. I did a lot of testing before I took the heat to the actual airframe.

Still got the wings, cowl, canopy, etc. - but below is my current progress…
Thanks again, Scratchbuilders!
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Old May 30, 2014, 01:07 PM
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Nice job!

Chris
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Old May 30, 2014, 05:07 PM
Slipping the Surly Bonds
dz1sfb's Avatar
Attica, MI
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Quote:
Originally Posted by compressor man View Post
Nice job!

Chris
Ditto, very Snice!

Ken
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Old Jun 06, 2014, 04:05 PM
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Joined Jul 2000
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Start your taping from tail to nose. That way you will have less drag and the air pressure won't tend to lift the tape over time.
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