Fokker D8 wing streaking test update

FlyingRazor · 13 June 2005, 10:36 AM

An update on the streaking. I attached a couple of photos showing a 1/4 scale wing covered in birch aircraft plywood that was stained with the packages from Koloman (Austria) who is completing full scale wings now. Turns out that the stain really soaks and spreads into the wood quite quickly, sort-of surprising. This meant that the two adjoining colors could not have a sharp edge, making the colors overlap and mixing into each other around the edges. The first photo is the raw plywood ready for the stain. The second is the two top colors brown / green and the last photo shows the blue / purple. I can see how the sun can easily fade these colors. A UV protection coat will be added. This test was done on Del Johnson's D8 where he plans to bring this plane to the upcoming Dawn Patrol (Dayton) event. It will take me some time to get use to seeing the new stain scheme versus the olive-green wings that have been campaigned for decades... Any comments ?

deljon · 13 June 2005, 05:13 PM

A correction on Glenn's post.
The first picture is not the bare or raw ply surface.
On the test peices since the streaking pretty much bled together or wicked along the grain, (almost a solid coating), we decided that we needed to seal the grain. I took a sample of the ply to Lowes and had them match the paint to it in latex-enamal. Painted it that evening and let it dry good overnight, then we started on the streaking.
This probably wouldn't need to be done on the full scale since you wouldn't need very narrow and small streaks.
All four colors behaved differantly with the violet being the hardest to work with. On the test samples the clear coat also brought out the color a little more.
Once I get the crosses painted on I will seal it with MINWAX'S Helmsman spar urethane. It's supposed to have a good UV protection.......we'll soon see.

Fokker's Forever
Del Johnson

deljon · 13 June 2005, 05:31 PM

A couple of close-ups of the color seperation.

Fokker's Forever
Del Johnson

womenfly2 · 14 June 2005, 05:17 AM

It would be interesting to see if after the top coat is applied, i.e. varnish, if a B&W picture could be taken with the same lighting and view as some actual pictures to see if the streaking effect shows up the same way for comparison.

Just a thought ...

Hard to get use to those stain colors, after all these years in O.G.....

WinterHawke · 14 June 2005, 06:45 AM

womenfly2,

I am sure that the clear top coats are going to be a factor in how this scheme works. I was down in Cincinnati this last weekend giving Del a hand with the staining, and got a chance to see it in action. One of the many tests we did was putting a clear coat over a test panel, and there was some smoothing of the colors - the streaking becomes less pronounced, but is still there.

Because it's a stain, anytime anything remotely wet gets near it, there is a color transfer. When I left late Sunday, the last item Del's working on is painting the crosses on the wing in black and white. The first pass using white on the violet (this is on a test sample, not the actual wing!) showed a very large amount of bleeding of the violet into the white - which turned a very light purple almost immediately!

Pretty, but not at all the goal!

I'm sure that the clear topcoat is going to do some of the same, and the appearance of the wing is going to change.

As a note, the streaked appearance was NOT easy to achieve - the stains would have been far happier soaking into the wood rather than streaking - anytime they were applied (again, to the test samples) the least bit heavy, or wet, they looked more like an exploded inkpen in a white shirt pocket rather than a WWI fighter!! IMHO the streaked effect was not an accident - Fokker went out of their way to achieve it!!

Best regards,

Lee McDuffee
the WinterHawke

womenfly2 · 14 June 2005, 07:45 AM

My thoughts (questions):

1. Would the stain have been applied to the bare plywood only.

2. Was the plywood surface sanded.

3. How about the areas were there was glue out side the join that soaked into the ply layers.

4. Glue would inhibit the absorption of stain. Causing very light stained spots.

5. The stain would have soaked quite quickly into the wood only if the wood fibers were soft, darker coloring, as if wing was sanded or if the wood grain was raised.

6. Plywood has a burnished finish from the mill and sometimes a waxy type coat from the fabrication of ply bonding, stain would have not soaked into the wood as much as laid on the top surface, lighter coloring.

7. Type of brush used equals how much stain it would have held and how long to pull.

8. Brushed recharged more then once on same pull. Dark to light and dark to light on same pull.

9. How concentrated was the pigment in the stain mix, ratio of solids to carrier.

10. What was the carrier for the color pigment.

The wing color looks very dark in the photos posted here and in books or is the dark wing color due to picture ageing?

Del's wing looks very light in color, will varnish darken it?

WinterHawke · 14 June 2005, 08:27 AM

1. Would the stain have been applied to the bare plywood only.

Yes. However, in our tests, we had trouble scaling down the effect to ¼ size. So a preliminary coating was added to help. While Del’s wing is ¼ scale, the grain of the wood is not!

2. Was the plywood surface sanded.

Lightly sanded. The skins are very thin (1/64th on the model), and there’s not much room for too much sanding. At some of the edges, the much darker underlayer becomes visible when sanded. The sealer Del used was color matched to the color of the plywood, to help mask this.

3. How about the areas were there was glue out side the join that soaked into the ply layers.

4. Glue would inhibit the absorption of stain. Causing very light stained spots.

The color is noticeably different over the glue, as one would expect. On the model, CA glue was used – something unheard of 90 years ago. This was another reason for sealing the wing.

Again, the sealer only slowed down the absorption, it didn’t eliminate it – the goal was to miniaturize the effect.

5. The stain would have soaked quite quickly into the wood only if the wood fibers were soft, darker coloring, as if wing was sanded or if the wood grain was raised.

If the stain was the least bit wet, or heavy, it wicked in very quickly, and it didn’t seem to care what it soaked into (you should have seen Del’s hands!)!

6. Plywood has a burnished finish from the mill and sometimes a waxy type coat from the fabrication of ply bonding, stain would have not soaked into the wood as much as laid on the top surface, lighter coloring.

The 1/64 ply does have a finished side, but it still is porous, and the stain was very happy to soak in given the chance.

7. Type of brush used equals how much stain it would have held and how long to pull.

We actually found the brush made a big impact! Softer brushes retained more liquid, and it was almost impossible to get the stain to streak. A stiffer brush worked much better – I believe that Dan-San mentioned in Langdon’s thread on the subject (referred to very frequently this last weekend!) that he felt that something like a wallpaper brush was used by Fokker.

8. Brushed recharged more then once on same pull. Dark to light and dark to light on same pull.

Actually, the brush was infrequently recharged. Very little stain was needed to accomplish the streaking. More time was spent getting the load on the brush right – the technique ended up being a kind of dry brushing rather than painting with liquid.

9. How concentrated was the pigment in the stain mix, ratio of solids to carrier.

We ended up being happiest with the stain mixed per the instructions. One packet of the powdered stain was mixed with ½ Liter of liquid. Thinning later just made it harder to get the brush “dry” enough to streak the stain.

10. What was the carrier for the color pigment.

Del used denatured alcohol - Alcohol was what was listed on the packet. It was mixed, per the instructions, by first heating a pan of water to about medium-low, then a second pan of alcohol was set into the heated water. The heated alcohol was then mixed in the final container with the powdered stain.

As a note, our references were the above mentioned Thread by Landgon on his research on this subject, in particular his photos of the streaking tests. We balanced those against Dan-San Abbott's drawings on the subject plane, and the Stec photo (post 101).

It was a very interesting weekend, and I can't wait to see the finished results!

'til later,

Lee

womenfly2 · 14 June 2005, 10:16 AM

" It was a very interesting weekend, and I can't wait to see the finished results!

'til later,

Lee "

Thanks Lee & Del for all the fantastic educational material here and all the time your spending on this. We all look forward to your enlighting efforts.

Thank you!

Dan_San_Abbott · 14 June 2005, 02:57 PM

WinterHawke:
The streaking is too light, the color have more intensity.
Blue skies,
Dan-San

WinterHawke · 14 June 2005, 03:30 PM

Dan-San,

I was a bit concerned on the intensity of the colors. The upper surface green has had a second pass over it to richen it up, and to get it more in line with the other colors. The undersurface violet is very pronounced, and I was afraid it was too intense!

The wing in person is a bit more colorful than the photos show - we had a terrible day with taking pictures - it was overcast and cloudy.

I was also concerned about the clearcoats - the test piece we did appeared to darkened and richen considerably - this may also come into play.

I'm pretty sure we can add more color to it, but we weren't as sure we could take color off of it once on - those stains are tenacious!

The photos that Langdon has posted of his replica wing and the test colors they have done so far show very light colors - I was terrified that Del and I had already gone overboard!

I'm going to see if any of the photos that I took while I was with Del this weekend show the colors any better. If so, I'll try to get them posted tonight.

Many thanks for the input - yours was one of the voices we were hoping to hear from!! And also thanks again for the drawings you sent - we're trying to follow them as close as possible (I surprised Del last Christmas with them!!).

Again, many thanks, and we'll keep everyone posted.

'til later,

Lee McDuffee