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Old Feb 10, 2013, 01:52 PM
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In case there's still anyone interested in all the testing I've done here, I'll post this.

This will be one the last of the experiments done on this model.
The two test frames were covered in tissue that closely resembles the stuff from easybuilt. One I used gluestick and the other thinned Elmers white glue to adhere the tissue.

When stripping the frame for the hundredth time I noticed the glue stick stays gummy and alochol makes it sticky again. humm.......Could this be the problem?

The frames were water shrunk and left overnight to dry. Both were nice and tight.

The frame that used the glue stick was coated with 3 coats of Rustoleum spray lacquer that was sprayed into a bottle and thinned slightly and brushed on.
The other frame was coated with 3 coats of thinned Aerogloss.
The frames were left for 24 hours for the coatings to cure before the results were compared.

The Aerogloss coated tissue is now drum tight and the lacquer coated tissue is loose. I'm now starting to wonder if the lacquer thinner is softening the glue stick just enough that as the tissue is shrinking it's sliding in the softened glue preventing it from getting taught...

As an absolute last experiment, I'll cover the frame one more time using thinned Elmers and then coat with the rustoleum lacquer.

I made a short video of me tapping the covered/doped frames on a dope bottle lid. You can hear the difference, one has a nice tight 'ring' and the other a dull thump...

Link to video, http://www.rcgroups.com/forums/showt...2#post24093582
Glenn
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Old Feb 10, 2013, 02:31 PM
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Originally Posted by glewis View Post
In case there's still anyone interested ....
Glenn,

This is a riveting adventure! Is your nickname "Bulldog"?

Gene K
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Old Feb 10, 2013, 02:52 PM
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Hey Gene.
I just can't give up until I find something that works like the stuff I'm used to using.
Decent (non Esaki) tissue is getting hard to find, silkspan seems to have vanished and Aerogloss is gone too. What's next, the EPA bans everything and the only legal glue we will be able to find is Elmers school glue???
Yeah, guess I'm just a stubborn old sombitc_ and won't give up without putting up a fight!
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Old Feb 10, 2013, 02:57 PM
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Originally Posted by glewis View Post
...One I used gluestick and the other thinned Elmers white glue to adhere the tissue.

The frame that used the glue stick was coated with 3 coats of Rustoleum spray lacquer that was sprayed into a bottle and thinned slightly and brushed on.
The other frame was coated with 3 coats of thinned Aerogloss.
The frames were left for 24 hours for the coatings to cure before the results were compared.

The Aerogloss coated tissue is now drum tight and the lacquer coated tissue is loose. I'm now starting to wonder if the lacquer thinner is softening the glue stick just enough that as the tissue is shrinking it's sliding in the softened glue preventing it from getting taught...
Yes, we are still interested in your experiments.

Unfortunately you changed two variables in one experiment. Now you don't know if difference is due to the lacquer thinner softening the glue stick adhesive or if it is simply that the Aerogloss has a better shrinking ability than the lacquer.

To really determine if it is the lacquer thinner softening the glue stick, you need to apply the lacquer to both frames and see if there is any difference. To determine if it is a different shrinking ability of the Aerogloss vs the lacquer you need to adhere the tissue to both frames with the same adhesive and then apply the Aerogloss to one frame and the lacquer to the other. i.e. change one variable at a time.

Larry
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Old Feb 10, 2013, 03:36 PM
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Thanks for the input Larry.
Yep, spent plenty of time in the lab and know the drill. I was trying to shortcut a little, but as usual changing more than one variable at a time didn't save me any time, I should know better.

However, there have been a lot of other permutations of these experiments that I haven't posted and I have found that the gift tissue doesn't work well at all.

I do now have a control sample, the white glue, tissue and Aerogloss combo worked fine. I was having trouble getting the glue stick/aerogloss combo to stay tight and is why I switched that frame to white glue.

So I have now isolated the shrinkage problem to the lacquer, gluestick or both and this last experiment should provide the answer.

One constant of these tests has been the use of the gluestick. (both Elmer's and UHU)
If it is determined the gluestick is the problem then maybe the minwax lacquer I tried about a hundred experiments ago might just work?

Glenn
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Old Feb 11, 2013, 02:54 AM
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Glenn,
I'm most certainly interested, since I have a Sperry to cover. I'd rather know how the dope type finish works with the glue stick. Thinned white glue just sounds so messy. Yeah, I know, nothing like as messy as wet covering using dope as adhesive.

Pete
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Old Feb 11, 2013, 12:01 PM
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Last night I was going to continue with the dope substitute experiments. I had a test piece out in the shop that was coated with the automotive lacquer. The tissue was loose and wrinkled even after 5 coats. Plan was to strip it and re-cover using white glue for the adhesive this time. The thought was the lacquer thinner might be softening the glue stick allowing the tissue to slide as the lacquer shrinks.
I brought it in the house and set it on my build table to start stripping the tissue then got distracted by something else. When I got back to the piece, the covering was nice and tight. HUH!!! What the-----?

So just the difference in temperature and or humidity caused the tissue to slacken and tighten, just like on my Stuka. The Stuka was covered using white glue and easybuilt tissue coated with Deft lacquer.So what does that tell us?

Could this be because the coating is not moisture proofing the tissue? Or possibly the glue stick and white glue softened ever so slightly when the tissue was wet during the shrinking process?

Tonight I will strip and recover. I think I'll take the part out to the shop and shrink the tissue there to avoid the temp/ humidity change. Then I'll start applying coats of the thinned auto lacquer as the final test.

I'm getting so little shrink out of these lacquer products I might as well just order up some non taughtening nitrate dope and be done with all this crap! It will probably shrink about the same amount.

I spoke with a friend who had covered a small wing in tissue and the dope warped it to an unusable pretzel. I asked what dope he used and it was SIG Nitrate. I thought for sure he used butyrate...

Pete, actually the white glue is easy to do. I put about a teaspoon into a pill bottle lid then add about 3 drops of water to it. I use a small cheapie stiff brush to apply the glue to the framework, working a little area at a time just like when using dope. Nice thing is the white glue gives you a chance to scoot the tissue a bit and pull it into position unlike the glue stick that grabs and holds the tissue too quickly for me.
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Old Feb 11, 2013, 12:17 PM
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Glenn,
I've just been reading Paul Bradley's Monocoupe thread, including details of his tissue covering technique. He applies glue stick to both tissue and wood, allows both to partially dry and then uses a covering iron on low heat to apply the tissue. It doesn't actually grab until the heat softens the glue. If he can use it on a 1/32 sheet wing, I might try something similar on the Sperry. Now I'm thinking about printed tissue too. DOH!!!!

Pete
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Old Feb 11, 2013, 01:24 PM
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[Paul] applies glue stick to both tissue and wood, allows both to partially dry and then uses a covering iron on low heat to apply the tissue.
In my experience, to apply tissue to sheet balsa, I find it much easier to just use spray adhesive, as I do to cover Depron. Takes some care in "rolling" the tissue on, smoothing it as it's applied. To do that, I often tack a small piece of the tissue to the end of the balsa/foam, then hold the piece upside down, letting gravity hold the tissue off the piece, all the while using my fingers to smooth the tissue on, starting at the tack. Does that make sense?

Again, that's just to cover balsa sheet, not to apply tissue to stringers ....

Gene K
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Old Feb 11, 2013, 02:18 PM
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I tried Paul's heat activated glue stick method to attach the printed tissue to the Starship Enterprise I built from his plans. Didn't work worth a dam <sp> in our Florida humidity, the tissue edges curled up and the tissue fell off. Then I tried heat activated spray adhesive and it worked much better. Heat activated glue stick might work ok on a wood frame since it will be sealed with some sort of lacquer product later to make it moisture proof. I have also heard of using white glue the same way, like balsarite.
Now that might be worth trying,,,, Double Do'H!
I have always doped tissue onto sheet surfaces. A couple of coats of full strength on the bare wood then use thinned dope allowed to soak through the tissue to adhere.
Glenn
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Old Feb 12, 2013, 10:25 AM
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Quote:
Originally Posted by glewis View Post
"...silkspan seems to have vanished..."
Glenn,

Guillow's stocks lightweight silkspan as "parts" for their many kits. Check it out here:

http://www.guillow.com/whitesilkspancovering.aspx - $2.50 for two sheets (about 18"x24", if I recall correctly).

Steve
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Old Feb 12, 2013, 11:10 AM
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Funny you mentioned that Steve, because...

I stripped and recovered the test frame last night. I took it out to the shop to mist it with water and let it shrink.
Then thought maybe I'm adding another variable to the experiment, so i took it back inside to use the same process as the doped control sample.
The tissue was misted with water and allowed to dry. It shrunk up nice and tight. Let it air dry for 2 hours to make sure it was dry.

Took it out to the shop to coat with lacquer. I decided to let it sit for 10 minutes just to see what happens. Didn't have to wait that long, within a minute of getting out there, I could actually see the tissue relaxing as I held the piece in my hand. After 10 minutes it was a wrinkled mess. Now I know it's the tissue, not the glue stick.... I tried misting the tissue again and leaving it out in the shop to dry. It wasn't completely dry when I went to bed but it didn't look to be any different.

I had this same problem with the easybuilt tissue and the stuff I'm using has the feel to it. It has a very soft feel, sort of like silkspan but it isn't. After coating it has little fuzzy hairs sticking out of the surface that would require sanding before paint. Something about the change in humidity is making that type of tissue relax.

The doped control piece was done right after a cold front passed and the humidity was low. This could be why I can't duplicate that surface tightness with lacquer.

Looks like the only way to get the results I'm after is order the tissue from Guillows. I could use Esaki, but that will be another learning process I will save for another time.
Glenn
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Old Feb 12, 2013, 05:49 PM
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Glenn, what size prop are you going to use with this setup? The PZ UM P-51 motor uses a 130mm prop (About 5.1 inches) . Is that size sufficient for the Guillow conversion?
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Old Feb 12, 2013, 06:12 PM
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I'll use the stock 130mm P-51 prop. The scale prop shown on the plan is 5", so it is perfect for the 18" span WWI models.
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Old Feb 12, 2013, 06:23 PM
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Good. I have a Guillows 18 inch SPAD kit and the SE5a plans so I would like to build those as electric. Thanks
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