Bearhawk Aircraft Bearhawk Tailwheels LLC Eric Newton's Builder Manuals Bearhawk Plans Bearhawk Store

Announcement

Collapse
No announcement yet.

Need some painting advise

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Need some painting advise

    The majority of my Bearhawk will be painted Silver Metallic with dark green trim. I didn't realize when I picked the color that it is the hardest color to get a nice looking result. Very easy to end up with darker streaks, or a mottled appearance. Before painting any parts I sprayed some 4' x 3' practice pieces. The second one actually turned out looking very good. I started spraying the smallest pieces and then moved on to control surfaces etc. I have had mixed results. Using what I think is the same technique, one side of a horiz stab will turn out great and the other side will have streaks. I've already resprayed the top of one horiz stab and the rudder to get a better outcome. I really think part of the problem is the spray gun. Its the Devilbiss Tekna which is what Stewarts recommends, but it seems very prone to clogging some of the minute air passages during a spray job and changing the spray pattern. I originally started with an Iwata W400. That's what I used on the practice pieces and got good results as far as even color but had orange peel texture. It was designed to spray at 10psi and talking to Andy at Stewarts, he said the Ekopoly requires about 20 psi to avoid orange peel so I swapped guns. Now I need to paint the wings and fuselage and I am really worried about how they will turn out. I would gladly hire someone with Stewarts experience to paint them, but I know of no one nearby. I know a couple Bearhawks have been painted with Stewarts Silver Metallic, would sure love to hear from someone who can give advise.

  • #2
    You probably remember this thread: https://bearhawkforums.com/forum/bea...icant-progress

    I tried to push the memory from my brain but I’m pretty sure we have 9 coats of paint on one side of our fuselage due to repeated attempts to not have striping. If I’d just called the guy in MT and paid him to help me paint my airplane would look significantly better and would probably weight measurably less.

    The two things that made a difference for us were keeping the flakes in solution and perfect gun control. Holding the gun the same distance from the fabric on each pass is critical. The paint is extremely sensitive to gun position.

    Some guys put a couple marbles in their gun to help swirl the paint while spraying. We tried this and it didn’t help so we didn’t use marbles and just gently swirled the paint occasionally while spraying.

    Putting it on a little wet will also cause the flaks to run but this will look like runs vs tiger stripes.
    Scratch Built 4-place Bearhawk. Continental IO-360, 88” C203 McCauley prop.

    Comment


    • rodsmith
      rodsmith commented
      Editing a comment
      What seems to work for me is cutting the fluid amount back on the wet coat to where I am using a very tight overlap to bring up the gloss, advancing each pass about an inch. When it works, it looks very nice. I seem to do better on flat surfaces. The 4 tank covers look great but then I do the stabs which are no larger and run into problems, so maybe keeping a consistent distance is part of the problem. Very frustrating that I don't have the technique down at this point.

    • whee
      whee commented
      Editing a comment
      I would think that reducing the paint flow which then requires tighter overlaps and more passes would introduce more opportunity for striping. But I’m so far from good at painting that all I can really offer is empathy. I’ve been where you are and don’t know how to fix it.

  • #3
    I hate to take information away from here but you might consider posting some pictures and your questions on the Facebook group. The Stewart’s guru is active on the Facebook group and may offer some suggestions.
    Scratch Built 4-place Bearhawk. Continental IO-360, 88” C203 McCauley prop.

    Comment


    • rodsmith
      rodsmith commented
      Editing a comment
      That's a good idea

  • #4
    Rod, can you outline your spray technique? I've sprayed quite a bit of Stewarts and have mitigated the tiger striping problem with the following technique. By the way striping is a concern with any highly metallic paint regardless of brand or paint type.
    First coat is a light fog coat to provide tack for the rest, let it tack up
    Fog coat up to color saturation with alternating cross coats, let it tack up
    One or two medium/wet coats with higher fluid volume and tighter overlap. One at a time
    The guns you suggest are all good as long as they're working correctly. If you're getting good results on one side then what is the variable for the other side? Temp, humidity, mix, lighting? Something has to be different.
    Silver sucks - but not as much as yellow.

    Comment


    • #5
      Technique is pretty much as you describe through fog coats. I turn the fluid volume up for the wet cross coat, not quite getting full gloss in the first direction. 2nd direction I really tighten up the overlap with gloss coming up a couple passes behind. My thinking is I will get a more even coat building the thickness over multiple passes. Sometimes it works great, other times I get streaking. I can't identify what I am doing differently. I always check the spray pattern before mixing the paint but sometimes can see that the spray pattern isn't even when I am into the wet coats.

      Comment


      • #6
        I would try that Iwata, mine has a better fan than any other gun. You're mixing 4:1:1 with a 1.3 tip?
        I've had success with other metal flake paints by over reducing by 10 percent or so. Maybe a little more water? I forget what the viscosity is supposed to be but it's a range, try it at the fastest time. It should let the flake disperse more easily

        Comment


        • rodsmith
          rodsmith commented
          Editing a comment
          To get into the viscosity range of 20 to 24 seconds I had to add about 40% more water than recommended so more like 4:1:1.4. This was with the #4 Ford cup from Stewarts. The one I got from Amazon wasn't even close. I'm still at the slow end so will try a bit thinner. Yes on the 1.3 tip.

        • N942VT
          N942VT commented
          Editing a comment
          That seems like a lot of water. Curious how fresh the batch of paint is, it will get thicker as it sits in the can. I try to keep it less than 6 months old.
          Wish I had more for you

      • #7
        Originally posted by whee View Post
        I tried to push the memory from my brain but I’m pretty sure we have 9 coats of paint on one side of our fuselage due to repeated attempts to not have striping.
        What I found is eventually the paint cracks, if it's too thick. After a few hundred hours there were cracks all over our gear legs where I doubled down on top of existing paint.

        Comment


        • #8
          I second the iwata. I turned my pressure up to what stewarts recommended and the iwata still worked fine. I only got orange peel if the gun was to far from the surface. I did not spray any metallic paint however so can't help there. I tried to spray at the thinner end, but can't remember the time, or which cup I have, for that matter.

          Comment


          • #9
            Originally posted by Battson View Post

            What I found is eventually the paint cracks, if it's too thick. After a few hundred hours there were cracks all over our gear legs where I doubled down on top of existing paint.
            Sounds like I’ll get a second crack at nicer looking paint job.
            Scratch Built 4-place Bearhawk. Continental IO-360, 88” C203 McCauley prop.

            Comment


            • Battson
              Battson commented
              Editing a comment
              Sadly, yes I am also looking at doing this for our gear legs...

          • #10
            Sold the Iwata. It was a model that was optimized for metallics and supposed to run at 10psi, generally the W400s run at 14psi. When I tried a higher pressure it blew out the center of the pattern. I would say the Iwata is a better gun than the Tekna so really sorry it didn't work out.
            Last edited by rodsmith; 11-10-2020, 11:24 AM.

            Comment


            • #11
              I'll preface this with admitting I've never sprayed a plane, just lots of cars. That being said, if you can't get a good paint job out of an Iwata, it's not the gun. Not trying to be rude, but unless there was something wrong with the gun (unlikely), the gun will do exactly what you tell it to do.

              Same time, silvers are typically the hardest color (other than white) to spray. When you add metallic to the mix, I would say they are THE hardest to spray. Those tiger stripes stand out when other colors will hide them to some extent. Best advice is to keep trying to dial in your technique. Try different techniques til you find the one that works for you and that you can do consistently. It's rare that you'll meet two painters using the exact same technique, everyone develops their own twists and tricks that work for them.
              https://www.youtube.com/user/fastfox23
              Patrol plans #398

              Comment


              • #12
                I can feel your pain. It is expensive & it is frustrating. It is really hard to get the metallics on even and it is an exercise in patience. We used the Stewarts in an Emerald green metallic and an off white metallic. The dark green was a problem not so much the white. There are 3 of us and it got heated sometimes. From our experience. We weighed all the components on kitchen scale in grams so every batch was identical. It was kept as well mixed as best as possible as it is hard to keep the metallics in suspension. One sprayed it while another mixed the next batch. We did the fogging and two wet topcoats that was the only way it was uniform and glossy. One thing we did not get was any orange peel and it is glass smooth. There is some slight very slight variances that are not obvious at first glance & that may be a different mfgr paint batch thing . The gun was a DeVilbiss Techna and I think the air was closer to 20#. One thing we did was put in oversized hose couplings so that there were no restrictions on the hose so the air flow is best as it can be. Have an air gauge regulator on the gun so the reading at the gun is accurate set with the pressure with the trigger pulled. Lighting is important and there needs to be a lot. Being 3 one sprayed and another helped with positioning or lighting another mixed. We hung white poster board and checked the gun settings every time. be consistent on the distance and be consistent on the speed of the passes. Could ask Stewarts about using a paint shaker to get it well mixed up as it probably better than any stirring. Put the paint in a shaker a day before to get it well mixed up. It would get the bottom free of any sludge settled over time so there is even mix and be easier to mix when making spray batches. Be consistent and do any changes incrementally until you find what works for you. That's all I have.
                Last edited by Glenn Patterson; 01-13-2021, 11:20 PM.

                Comment


                • Glenn Patterson
                  Glenn Patterson commented
                  Editing a comment
                  Russell is spot on about everyone sprays different and find what works for you. That can be very trying. Key is incremental changes and it would not hurt to keep a note on the gun settings like turns on the air and paint knobs.

              • #13
                I forgot to add the note to pour the paint into the spray gun pot through a good quality fine paint filter like those used for painting cars. The filters are better than those found in a hardware store. We bought a sleeve of them from a local auto supply that sells auto paint and even used them in a funnel for fuel. Particles show up occasionally no matter how clean one tries to be. Those bits may come in the paint at no additional cost. :- )

                Comment


                • rodsmith
                  rodsmith commented
                  Editing a comment
                  I'm using the recommended filters bought from Stewarts.

              • #14
                [QUOTE=Russellmn;n60893]I'll preface this with admitting I've never sprayed a plane, just lots of cars. That being said, if you can't get a good paint job out of an Iwata, it's not the gun. Not trying to be rude, but unless there was something wrong with the gun (unlikely), the gun will do exactly what you tell it to do.

                I had better luck getting a uniform look with silver metallic using the Iwata. It is great gun. Problem was it was designed for metallics and spraying at 10psi. At 10psi I got a lot of orange peel texture. Stewarts needs higher pressure to avoid orange peel. I tried using it at 20 psi and it blew out the center of the paint pattern. Went to the Tekna and 30 psi and no orange peel, but I haven't yet found a technique to avoid the striping. In November I talked to a Stewarts tech who has recently been painting a Waco silver metallic. Got some good tips from him but haven't been able to try them out because the weather turned too cold to paint with my setup.

                Comment


                • #15
                  It has been 6 years but the pressure with the Techna was higher and you are on the right track. Things to maybe look at for striping is the overlap and how wet it is being laid down. It is a personal thing as previously mentioned between painters. One of us could get the gloss w/o orange peel with one top coat while the other had to do it in two coats to achieve the same result. That was part of the angst. Also when we were painting Stewarts were changing to the fog method with a wet top coat and there was a formula change that threw us off. The striping may be the overlap pattern that you could experiment with. For example a 1/3 overlap leaves the top and bottom of the passes with 2 passes each while the middle of each pass only sees one pass. If that makes sense. Perhaps try a 50% overlap with different settings if you are not doing half laps. We had to order more to be able to finish. It made no sense that our white was a metallic and went on good after some learning. The green was completely different and do not if the metallics are heavier to show through or the white was more forgiving. A lot of green paint was shot at white poster board over the course of painting checking patterns and trying to find what worked. I think between the poster board and what went on the floor there could have been as much green paint there as went on the airplane. Better to work it out on the poster board even if it takes an extra quart than build it up on the airplane. It is not only the risk of cracking but the weight of every can of paint and hardener is the same weight laid over the airplane. It took a few conversations with Stewarts and they were good. Seems like you are on the right path & you will get there.

                  Comment

                  Working...
                  X