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Dope - Thinner Mix is still "Streaky:???

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Dope - Thinner Mix is still "Streaky:???

Old 05-04-2024, 08:03 AM
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Default Dope - Thinner Mix is still "Streaky:???

I have 3 layers of thinned dope (Butyrate White Dope 40% Thinner 60%) on Silkspan, and the results still came out pretty "streaky". I added one more layer of 60% White Dope and 40% Thinner which improved it a little, but not too much.

Is this an issue of incomplete mixing??? I pour 1 ounce (or slightly less) into a small jar (like baby food), add the thinner, and then stir completely with a small stick, After brushing on (artists brush) it still comes out streaky. This is on the wing of an (old) Super Ringmaster.

Any clues here? Thanks
aaganz


Old 05-04-2024, 01:22 PM
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It's drying too fast. Try less thinner.
Old 05-05-2024, 07:23 AM
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I think your not using retarder, a world of difference. Thinner can streak and blush, with white it can get that milkey texture. And you will never see it. Allowing the coat to dry. Will help that could take days, with lots of moisture in the atmosphere. Just my opinion!AJ
Old 05-05-2024, 09:33 AM
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Thanks for the input! What is "retarder"? I will try a 4th coat this after noon of Cessna White using only 10% Thinner and see what happens.

I am a little puzzled as the instruction sheet that came with the Silkspan from Brodak lists multiple coats of dope with lots of thinner???? I had bought the thinner from Brodak too, so assumed it was the correct method to follow! I will post the result later!

As kids, we just slobbered dope on the wings and everything worked out......although maybe not as tight and strong as I could do today!! This restoration plane is meant for 1 flight to prove it is still good, and then goes to display. Then I'll start on the second Super Ringmaster (also from 1953!).
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Old 05-05-2024, 01:22 PM
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Aaganz I buy retarder by the gallon. But Sig use to sell it in quarts, I think Randolph is the best. It controls blush and slows down the drying process that tends to smooth out the brush marks. Seventy degree weather and forty percent humidity usually gives you best results. AJ
Old 05-06-2024, 08:10 AM
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I did try a final 10% Thinner 90% White Dope coat on the Silkspan covered wing, and also used a real artists "camel hair" brush. It is quite dry this morning, but I will give it a few more days to even out. It is still slightly "milky and patchy", but ok for the flying I plan to do. It should look pretty good after 2 further coats of clear dope and the yellow stripes on the wings. The camel hair brush was shedding bristles which I tried to pick out, but the dope thickened up too fast to get them all.

For my 2nd Super Ringmaster (1953 - never completely finished) I will track down Retarder and see how much difference that makes! This plane will have red stripes.

I will post some photos of the current plane after the yellow stripes are on!

ps...I am planning the K&B 19 for leisurely flying. But I also bought a K&B 29 last night, and am making an adjustable motor mount so I can use the K&B Greenhead 19, 29 or 35, and can test them all.

aaganz
Old 05-06-2024, 11:19 AM
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Try Aircraft Spruce They sell retarder in Quarts. Pretty sure it's Randolph!AJ
Old 05-12-2024, 11:50 AM
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Thanks for the hint for Aircraft Spruce! I would not have thought to get model airplane finish products from a full size airplane supplier!!
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Old 05-13-2024, 09:46 AM
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Ya they are the only supplier I know of that’s still pretty nice as far as price goes. Wicks is another supplier.but I use spruce can pick it up Locally. I think quarts are the smallest size they sell. Also you might consider getting a top loader spray rig.I use a touch up gun. You will also need a compressed. Air. To run the HVLP low pressure high volume.AJ
Old 06-08-2024, 11:27 PM
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Love your dedication to getting it just right! Maybe try stirring a bit longer or adding thinner gradually to ensure a smoother mix? Good luck!
Old 06-09-2024, 07:12 AM
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If your OAT is high with humidity in excess of 40% you will get streaking unless you use retarder that slows drying, but still a spray gun is your best bet. For a smooth streak free finish. AJ
Old 06-10-2024, 01:36 PM
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The wings on my 1953 restored Super Ringmaster, still came out a bit streaky, and I will try retarder when working on the 2nd plane. However, I concealed it pretty well as you can see in the pictures I posted 5/18/2024 (Super Ringmaster Forum Link) . I lined up the yellow stripes with the worst of the streaking, and it hides them pretty well. In the Pix, the yellow comes out a deeper yellow than on the plane itself. The plane has Brodak Lemon Yellow,...which with the Cessna White, gives a nice light ghosty appearance.

I'll leave it like that for the first flight, and if it crashes and a repair is needed, I may adjust the color a bit. My 2nd plane will have red stripes!!

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