LesUyeda

This may be a little late, but be aware that "dope" comes in 4 flavors. Nitrate; taughtening and non-taughtening: Butyratel taghtening and non-taughtening.

Les

Zor

Hi Les and all interested in "cloth covering",

While cloth covering is the main topic of this thread I have no objection to other topics being brought up.
Pull-pull setups are also interesting to mention between friends.

About types (flavors) of aircraft dope, which I have used for decades, I found that tautening and non-tautening is not a black and white behavior. It is more a matter of degree. Non-tautening dope does a fair amount of tautening over a long time period and Ihave pictures to back this up.

Dope tautening not only tightens the fabric but also improves its surface finish with time.
It is not easy to explain in words so I will say that it appears as if the surface molecules keep relocating themselves so the surface keep on looking more shiny with time. It does that by itself. An experiment I made was to intentionally create brush marks and after a few weeks they had disappeared and the surface was even, smooth and shiny.

Possibly expert joker will affrmsome history in opposition. I can only relate my experience with dope.
Fabric and dope remains the strongest and most weather resistance for our models.

Zor

Edwin

My Feedback: (2)

This is good info zor. I never paid much attention to the tautening in the past, I just new it kept the fabric tight. Which is a big deal here in Texas. The heat regularly wrinkles mylar covers and needs to be reshrunk from time to time. I like the fabric finish using a tautening dope to keep it looking nice.
Edwin

goirish

Is this the kind of nitrate I need
http://www.aircraftspruce.com/catalo...lickkey=295678

Slavko

Hi Gang,
I know I don't post a lot but I've been following this discussion, and all discussions concerning cloth coverings.  What I've done on the last few planes I've built is to use Sig Koverall and attached the cloth with a product called Balsaloc.  Balsaloc is a water based adhesive that when dried is heat activated.  I've been very hesitant to use dope in my workshop mainly because it's in the basement and the fumes are pretty bad.  And yes, I keep the basement window open.  I'm no doctor, but I can't help but think that the fumes from dope are pretty harmful to one's system.  You might want to give the Balsaloc a try.  I then seal the weave using Minwax Polycrylic using a foam brush and very light coats.  Then painted with water based house or hobby paint.  It's a pretty labor-intensive method, but I really like the way the planes look and the covering is tough as nails.  Just a plug here, but Dave Platt has a video called Back to Basics that deals with the silk and dope, and other cloth coverings.  Well, my $.02 worth. 

Joel

Lowvoltage

Here is a series of articles on applying polyester fabric. In this case it is Ceconite Lite. The process is the same for Sig Coverall or Stits Polyfiber pretty much.

http://www.ceconite.com/articleselecting.htm

I think we all need to be mindful that you don't need taughtening dope if you use heat to shrink the fabric. Non-taughtening nitrate dope should be applied to the surfaces that the fabric will lay on. It serves two purposes. One purpose is to allow you to fine sand any surface imperfections after painting it on, but prior to covering. Another is to provide for additional nitrate dope (help it adhere the fabric) if you use nitrate dope to glue the fabric down.

Joe

chuck l

My Feedback: (17)

What do you thin nitrate dope with?

Chuck

Lowvoltage

I would use the thinner that complements the brand of dope Iam using.

If you are using Randolph nitrate dope:
http://www.aircraftspruce.com/catalo...lickkey=330752

If you are using Sig nitrate dope
http://www.sigmfg.com/cgi-bin/dpsmar...FV4.html?E+Sig

A lot of people will tell you that good automotive lacquer thinner will work fine. I don't know. Iknow the finish on Sig Butaryte dope cracks when sprayed over Sig Nitrate dope that has been thinned with MEK. That is just my personal experience.

Lowvoltage

I really think if you have a 1/4 scale or larger plane to cover and you want it to look like the original fabric covering to call Chip Mull or look at the web site at http://www.stits.com/

All of the material they sell is geared toward finishing an airplane in the original fabric covering and applying the correct color that will look very nice longer than you may live.

goirish

Hey Lowvoltage
I may live as long as Methuselah 969 yearsgood covering

LesUyeda

"About types (flavors) of aircraft dope, which I have used for decades, I found that tautening and non-tautening is not a black and white behavior."

If you follow the Aircraft Spruce link posted by Lowvoltage; peruse the left hand column, you will find butyrate; taughtening and non taughtening: Nitrate; taughtening and non taughtening

Les

Zor

The link to Ron Alexander article is interesting but I did not find a way to continue reading about the shinking process as it refers to in the last paragraph.

The cement recommended is available here only in gallon containers so I used stix-it and it worked fine.
Using the light Ceconite 1.7 oz weight per square yard I counted the threads per inch in both directions using a 10x magnifier and had a much different count than reported in the Alexander article.

Srinkwise I did not use heat. I let the dope do the tautenng and the finish is like a drum skin without having any risk of distorting the structure.

It is recommended to avoid nitrate dope as a cementing media for Ceconite; that is due to the structure of the individual threads of the fabric.

There is more than one method to be successful.

Zor

Lone Star Charles

Zor

The remaining articles (including the shrinking process) by Ron Alexander are located at the link at the top of the page. Look for the blue tab link "Articles by Ron Alexander". All are good information about using Ceconite covering.

I have used nitrate dope as an adhesive for Ceconite, Stits Poly-Fiber, and Sig Koverall. I have found it to be satisfactory. It is important that the structure be coated anywhere the fabric will touch; otherwise, there will be little pinholes in the finish as the dope gets sucked into the balsa structure below the fabric. I have also seen the recommendation not to use nitrate dope for an adhesive, but for our application, I find that nitrate dope adheres satisfactorily and gives a better finish than using the other glues. I’ve never had an adhesive failure.

Zor

Charles,

Thanks for your posting and directives.
I was expecting to see directions to the shrinking part where this text was being read "Our next step will be to actually shrink the fabric itself"

The nitrate dope will act as sufficient bonding agent with the proper technique of usage. The risk is that after sealing the periphery wih nitrate then spreading the fabric and then applying more nitrate, the new nitrate application softens the initial one on the wood and some fabric tension can be lost if the added nitrate is applied all over.

It is not easy to explain in text so I will add the following.

First the initial sealing coats should be left to cure fully, a good 24 hours.
Then spreading the fabric and adding nitrate should be done ONLY on the periphery and use two coats and let that again cure fully before applying nitrate over the whole surface. The idea is to avoid that the periphery coats be softened enough and thus prevent the tension from loosening. When I apply the coat all over I avoid doing the full witdth of the peripheral gluing thus avoiding softening the full width of the original cementing.

How clearly understandable is the above pararaph ?
The results of this technique (method) assures that the fabric does not slip from its original gluing.
I find an advantage of using stix-it because it is not softened much by the application of the nitrate.
I then apply all over with the second coat of nitrate.

Other types of covering and finishing may save work or save time but nothing will last and protect a model as well as fabric and aircraft dope.

Anyone can disagree, that is everyone's privilege but If they use it once they will enjoy its advantages.

Zor

YellowBlueBird

Does Randolph still make color dope? If so where on the web can it be found. Aircraft Spruce only lists clear by Randolph. Color by a CA company.

zippome

I have a quick question. (Hopefully quick) I have a can of 'Balsarite' down in my shop that i picked up somewhere along the way. and I was wondering if it is similar to 'Stix-it', or at least can it be used in the same manner to tack down Koverite?
Thanks .
Zip

Zor

YellowBlueBird,

Most retailers if not all of Randolph dope have facilities to color the butyrate to the color or shade the customer needs.

Zor

goirish

Well folks, I purchased some silk and nitrate. I am going to try my hand as cloth covering. I am fairly good with Ultracote and those types of covering. Guess we will see if the skill can be passed down. Purchased the silk from Dharma trading co. out of CA. Very fast delivery.

Lone Star Charles

goirish

I haven't done any silk w/ dope in over forty years, and that was on some old control line stuff. I have thought that it might be fun try it again sometime. If you are going to do this would you please continue this thread (or start a new one) with pictures?

Charles

flyingagin

Yeah what he said

Ken

cjet

Hi YellowBlueBird,

I had the same problem, but finally found the colored Randolph on the Aircraft Spruce page. When you get to the Randolph clear, drill on down (the left side if I remember) and at the very bottom is a link called color selector. It will display a color chart for you of Randolph dope.

Good luck ...

Zor

As I wrote earlier, the retailer does the pigmentation.

Perhaps retailers do not all have the same color selection but there is a variety of colors that should be suitable for any modelers.

Zor

warbdluvr

Wow guys, what a great thread. Thankyou everyone for all the great information. I have a 1/4 Tigermoth that can only be done justice with fabric. I've been sweating about trying it for the first time. I'll be following this thread for all the great info everyone has posted and I'm quite confident now about trying it. Granted, I will be perfecting my process on something a little less important lol. I think my Sig Citabria might be a great candidate.

Zor

Not "might be" ___ITIS a good candidate.

Zor

warbdluvr

Point made. Think this is going to be fun.