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Stewart Systems Alternates/substitutes

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Vigilant1

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TiO2 is an inexpensive and ubiquitous white pigment used in a lot of paints (and serious sunscreen products for the skin).

The main takeaway I got from him, was to use the best premium latex product I could find (of any mfr) with the highest concentration of "Titanium Dioxide". It is TiO that is the main source of UV protection. He further stated that in the primer coat, we should add TiO to further increase its effectiveness on fabric protection. It is not expensive at all and I have a small package ready to mix and use when we get to that point in our build. I will post here our experience in using it.
This could explain why white/light paints and primers reportedly protect the fabric slightly better than dark paints and primers-- more TiO2.

Please let us know how much TiO2 you decide to mix in, where you sourced it, particle size, and if it left any clumps. If you get a chance, a sample of fabric with and without the added TiO2 left in the sun for a few years might give some interesting info.
 
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rv7charlie

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My understanding is that the UV protection in the paint is there to protect the paint itself, so if the paint has enough UV protection, the fabric under it gets all the benefits 'for free' in the process of sealing the weave with the paint. Question becomes, when does better become the enemy of good enough? (At what point will the added material start to degrade the other properties of the paint?)

To the issue of UV in hangars: I'd agree that if the hangar is a closed, dark box 99% of the time it wouldn't be an issue. 'Shade hangars' would be a totally different situation. My 50' x 48' hangar, closed on 3 sides, didn't have a hangar door for many years, and UV-susceptible plastic items inside deteriorated fairly quickly, even in the back of the hangar. If you look at the pic I posted earlier in the thread, you can see a couple of windows in the back wall that have translucent curtains over them. The curtains are plastic shower curtains used to soften the glare of afternoon sunlight. I have to replace them every few years due to UV degradation. The windows are plain glass; the main hangar door is skinned with white 'Suntuf', a poly carbonate ('Lexan').

I forget sometimes that most people are with their planes only a few hours a month. I'm fortunate to be retired and to live next to my plane, so I'm in the hangar/shop 8-10 hours almost every day, with the doors open in decent weather. So, my 'stuff' is getting a (un)healthy dose of UV all the time. It's also worth noting that both fluorescent and HID lamps traditionally used to light hangars all emit low levels of UV, so when the lights are on....
 

Mohawk750

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Thanks this is helpful. I found similar info in my searches for "UV Blocker for Latex finishes". Adding the TiO to the first coat was recommended. Can you tell us where you bought the TiO additive?

With the Stewart System you brush a thinned coat of ekobond (3M 30-NF) over the entire surface to encapsulate the fibers prior to the UV coats. I've heard reference to the Gliddon gripper primer being applied in two cross coats for essentially the same purpose.

My point is, if the fabric is sealed with 30-NF could you not just add the TiO to your first coat of colour for fewer total coats and a lighter finish?

One other thought; around here 30-NF seems to be available in clear only. Since it's a latex base would it be reasonable to take a gallon to he local paint store and have them tinted it to your finish colour. It would add contrast so you can see how much you have on the joints while gluing and when brushed over the entire surface would leave an interior look similar to the exterior colour?
 

Vigilant1

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Pawing around on sunscreen studies: TiO2 is primarily used to attenuate UV-B (290-320 nm), while zinc oxide is the primary substance used to block UV-A ( 320-400 nm ) . The shorter wavelengths of UV-B are more energetic and damaging, but depending on other factors (spectral distribution of the sunlight, characteristics of the paint and fabric) it seems possible that the blocking of UV-A could turn out to be just as important. So, maybe TiO2 by itself isn't the whole answer.
 

Map

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I used Oratex fabric on the control surfaces of my old motorglider. It is much easier and quicker to apply, has the paint already on it and is lighter. I was able to do the covering in my living room, no mess. I think if you added up the cost for the fabric and paint for conventional systems, it may even be cheaper. It is certified for some applications.
 

proppastie

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The parts in yellow are my plan the paint has the silver.....my calculations (in theory) show this will be only slightly heavier than Oratex using the 1.8 oz fabric. Certainly not as easy to but much less expensive.
 

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Pops

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Friend of mine painted his M-Max and it set under an open roof for 10 years and still looked and tested great. He painted it with Sherman Williams Kryron Urethane Enamel. I did a test panel and painted the SSSC with it in 2007. The paint and fabric still looks great. The Silver has a lot of silver in it where you have to keep it stirred as you paint in on, ( brushed to work in into the weave good) I wanted to paint the JMR with the same paint but SW quit selling it in Qt, or Gallons, just in rattle spray cans. Had the local SW store call SW to try to buy several gallons.
No, rattle cans only.
 

Flyguyeddy

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With the Stewart System you brush a thinned coat of ekobond (3M 30-NF) over the entire surface to encapsulate the fibers prior to the UV coats. I've heard reference to the Gliddon gripper primer being applied in two cross coats for essentially the same purpose.
im pretty sure that is not accurate. The 30nf is only used to attach the covering to the frame, not as an all-over coating of the fabric.
 

Flyguyeddy

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im pretty sure that is not accurate. The 30nf is only used to attach the covering to the frame, not as an all-over coating of the fabric.
Turns out i am wrong. apparently i read an old manual version last time?
 

Mohawk750

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Well you made me double check!😁

I was going by memory when I wrote that but I see Section 10 of the current Stewart Systems manual covers it. It's available for free download if you need a copy.

Mark
 

WarpedWing

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After my convo with S/W, I looked around on the internet for sources of the TiO. I ended up purchasing from Pantai Chemical USA. They are in GA ( I live in FL). I actually made the purchase through their eBay store. It was inexpensive and I purchased an 8oz package of pure white, for less than $10.00.

Here is the link to the page below.

 

Vigilant1

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Here's an interesting article on TiO2 in paint, specifically what happens when UV hits the TiO2 particle. There's more to the process than we might think, and some of the results aren't great (TiO2 may cause degradation of the paint due to the products formed when UV interacts with the TiO2, and other substances are added to address this). Maybe the paint makers have the mixtures of various components just about right.

A Comprehensive Understanding of 'TiO2 Pigment Durability'
 

Mohawk750

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After my convo with S/W, I looked around on the internet for sources of the TiO. I ended up purchasing from Pantai Chemical USA. They are in GA ( I live in FL). I actually made the purchase through their eBay store. It was inexpensive and I purchased an 8oz package of pure white, for less than $10.00.
Thanks for the link, much appreciated.

Here's an interesting article on TiO2 in paint, specifically what happens when UV hits the TiO2 particle. There's more to the process than we might think, and some of the results aren't great (TiO2 may cause degradation of the paint due to the products formed when UV interacts with the TiO2, and other substances are added to address this). Maybe the paint makers have the mixtures of various components just about right.
I was unable to read the whole article without setting up an account??? I'm sure there is some good information there. There is no doubt much more to the chemistry than I will ever understand. The SW rep said more TiO is better so that seems like good advice and several builders are reporting 10 years or more from uncertified fabric and latex. To me that is about the right investment and lifespan I would be willing to live with for a small ultralight, like a legal eagle, skylight, J3 kitten or simmilar but may not be appropriate for your $50-$100K Oskosh winner.
 

Vigilant1

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I was unable to read the whole article without setting up an account??? I'm sure there is some good information there.
The site gives a few previews before asking folks to register (free). I could read it all before, but I apparently used up my last preview, I'll have to register with a "burner" email account when I can.
In a nutshell, the TiO2 particles generally do a good job of converting the UV to heat that is then shed to the paint film and then to the atmosphere or substrate. That agrees with what the S/W rep said-- the TiO2 is blocking UV. But in a small % of interactions the TiO2 instead creates some chemicals that are highly reactive and they break down the chemicals that form the paint film. It is a well known problem and paint formulators even "blame" the TiO2 for the problem. They include the TiO2 in the paint primarily for its hiding and whitening properties, not for its ability to block UV. So, to deal with this, they include other chemicals to neutralize these reactive chemicals. Those eventually get used up, and the paint film degrades more quickly. I'm not a chemist, but it seems possible that adding more TiO2 without adding more of the other chemical enhancers might result in faster degradation of the paint film. Also, I suppose it is possible that these reactive/radicalizing chemicals might also not be great for Dacron--might even be as bad as the UV.
I'm just putting it out there. If the as-is primer and paint is performing well in actual use, it might be conservative to just go with that. Meanwhile, add some TiO2 to other paint and do a test panel with a control panel (paint without added TiO2) and leave them in the sun for a long time. When your plane needs recovering in a decade, you'll know whether adding more TiO2 is a good idea or not.
 
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Mohawk750

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I would suggest getting some fabric scraps from an EAA buddy and building test panels before you even start your next project. You'll likely have five years of test data by the time you are ready for cover! 😁
 
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Built2Fly

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@Mohawk750, I got some 3M 30NF and covered a test panel. It seems to be working just fine (please keep in mind that I don't know how real Stewart EkoBond should look like). This is my first ever covering, so I have made all the mistakes one can make, brushing too much, brushing not enough, not wiping clean enough, etc.

One thing is that this 3M cement is almost colorless (light gray), which makes it a little hard to see comparing to the blue EkoBond in the videos. I am wondering if there are some way to add some color to it.

Here is my somewhat messy first job.

20210117_205439.jpg
 
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ransfly

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The green 30-NF is what American Champion uses to cover their aircraft. The current Stewart manual does talk about filling the weave with thinned Ekobond as well. Then using the Ekofill
 

Mohawk750

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One thing is that this 3M cement is almost colorless (light gray), which makes it a little hard to see comparing to the blue EkoBond in the videos. I am wondering if there are some way to add some color to it.
Thanks for posting. I covered one aircraft with the Stewart System 20 years ago. About the time you get it figured out your pretty much finished! My mistake was using too much adhesive, I'd brush it on too thick thinking more is better and had ridges along my tapes. What worked for me in the end was brushing the minimum amount of glue to fill the weave not much wider than the tape or lap joint, lay the fabric or tape on as ot's tacking up and then brush another light coat through the tape to wet it in. Then I took a folded paper towel and wiped down the legth of the tape or seem to remove any excess. Once cured I'd use my detail iron and melt in the pinked edges.

I'm no chemist but it's a latex product and I bet it could be tinted to help with the visuals. As far as what to tint it with I've notice that my local paint store carries several brands of paint but there is only one rack of tints. Every paint has a unique recipie but has to use the same ingredints for tint. Maybe take a baby food jar to the paint store and ask the guy for a dab of blue! Try it in a sample first to see if it mixs and then use it on a test piece to compare.

3M make the Fastbond in blue/green but I rarely see it advertised. In fact I can't find a retail outlet that carries Fastbond near me at all. Does anyone know who carries it in Canada?

Mark
 

Mohawk750

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The green 30-NF is what American Champion uses to cover their aircraft. The current Stewart manual does talk about filling the weave with thinned Ekobond as well. Then using the Ekofill
Does anyone know what the Ekofill recipe is? It seems like it could be watered down Ekobond with carbon powder added???
 
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