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Thread: paint question

  1. #1
    jimboflying's Avatar
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    paint question

    Can anyone tell me what caused this to occur in the Stewarts Ecoprime layer over Ecofill? Spray layer too heavy, paint too thin, temp to cold? Ideas?
    IMG_1249.JPG

  2. #2

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    I wish they would certify a more standard topcoat. I love their glue and Ekofill, and find that it is a good base for butyrate. We re-taped a fuselage, then another shop sprayed a urethane top coat over our extensive Stewarts repairs. Gorgeous! It sat outside for over three years - many parts of the aircraft, including factory new wings, suffered greatly, but that fuselage still sparkles with no cracks.

    My personality has a difficult time with very precise measuring of fluids - it is all I can do to set a carburetor up. When I spray paint it is a little thinner here, some rejuvenator there, some retarder maybe, all splashed into the gun, and zap. Stewarts finish will not put up with that.

  3. #3
    Bearhawk Builder's Avatar
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    Hard telling from the picture but I've seen ekoprime do something like that if you put too much on too fast. Should sand out easily though.
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  4. #4

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    It's hard for me to see from your picture, but I think I am seeing solvent popping. You may have applied a too heavy top coat over a not sufficiently tacked and maybe too thick lower coat. I fog coat until i get the color the way I want it, then I apply the last coat with the same gun settings, only closer and slower with the gun.
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  5. #5
    Bearhawk Builder's Avatar
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    Is it ekoprime or topcoat?

  6. #6
    skysigns's Avatar
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    Quote Originally Posted by Bearhawk Builder View Post
    Is it ekoprime or topcoat?
    you tried to spray it to heavy you need to do a light fog coat first and make sure to use a good water trap
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  7. #7
    G44's Avatar
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    My guess is water. Somehow water/moisture was introduced into the mixture.

  8. #8
    jimboflying's Avatar
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    It is ecoprime which was diluted with water 10%.

  9. #9
    G44's Avatar
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    Quote Originally Posted by jimboflying View Post
    It is ecoprime which was diluted with water 10%.
    Ok, well, there goes my theory then...

  10. #10
    Marty57's Avatar
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    A few hints for the EkoPrime. Regarding thinning it out, using a viscosity cup is a good way to ensure that the material is properly thinned. Viscosity in the 22 second range works well. Ekoprime is ready to be sprayed right out of the can but, if necessary, can be thinned with distilled water. No more than 10% water is recommended. Sounds like you thinned it ok unless it already had been thinned. Runs like that can come from a combination of issues or any one of the following: gun tip size, pressure at gun, and speed of application and distance from surface. With the Stewart Systems finishes, light fog coats are recommend even when using Ekoprime or Ekofill to build up surface thickness. I'm teaching the seminars for Stewart Systems and if you can give me some more info on your set up I can help figure out what caused the runs. As stated above, Ekoprime will easily sand out with 320-400 grit open coat paper (dry sanded) after just a few hours if temps are in the 60-70 degree range.
    Marty
    N367PS
    Psalm 36:7 "High and low among men find refuge in the shadow of His wing"
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  11. #11
    jimboflying's Avatar
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    Thanks for the many ideas. The setup used was a Rotary air compressor with lots of air available, Refrigerant air dyer, 50 psi at separator pressure regulator, 50 feet of 3/8 air hose with 2 wide orifice couplers, 25 psi at gun gauge available but set to 18psi, Binks M1-g HVLP gun, 1.4 mm nozzle, 1 light fog coat followed by a heavy wet coat as per instructions, temp of spray booth was 72-76 F. , spray distance about 7 inches.

    Since I was doing 2 wings, could the fog coat have dried too much before I got to the heavier wet coat and the thinner paint ran off?
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  12. #12
    algonquin's Avatar
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    Just a question, did you shoot primer over ekofill? If so why , I'm getting ready to shoot a wing tip. Thanks
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  13. #13
    algonquin's Avatar
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    IMG_1881.jpg I shot this wing with ekofill and Stewart's top coat right on the ekofill. The wing I'm doing now, the customer want urethane top coat and I'm thinking of shooting right on the ekofill. Marty 57 would you comment on this idea, thanks.

  14. #14

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    The reason for the ekoprime is to make it easier to shoot yellow. If your top coat is white, you probably do not need primer. I have never had adhesion problems over Ekofill.

  15. #15
    Marty57's Avatar
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    Quote Originally Posted by algonquin View Post
    I shot this wing with ekofill and Stewart's top coat right on the ekofill. The wing I'm doing now, the customer want urethane top coat and I'm thinking of shooting right on the ekofill. Marty 57 would you comment on this idea, thanks.
    That wing looks very nice; you have the EkoPoly application down. As far as shooting urethane over Ekoflii; why dosen't the customer want Ekopoly over the Ekofill? I gather the wing you are shooting now is also exp? Urethane over Ekofill isn't in the STC because those finishes were not tested together so not legal on a certified bird. A catalyzed urethane should work fine but when you start mixing different types of paint with different thinners (solvents vs distilled water) you definitely cross over into the experimental zone. Depending on the urethane, adhesion is somewhat of an unknown. Ekopoly and Ekofill are designed to be fully compatible so I would recommend to the customer to stick with the same system. If they want a clear coat that is available in Ekopoly. From the perspective of your warranty on the urethane top coat, if the urethane isn't comparable and issues crop up in a year or two what happens?
    Marty
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    Psalm 36:7 "High and low among men find refuge in the shadow of His wing"
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  16. #16
    Marty57's Avatar
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    Quote Originally Posted by bob turner View Post
    The reason for the ekoprime is to make it easier to shoot yellow. If your top coat is white, you probably do not need primer. I have never had adhesion problems over Ekofill.
    Bob,
    Agreed, yellow over Ekofill is hard to get color saturation without putting on more paint than needed. White or charcoal gray Ekoprime is very helpful for achieving full color saturation. Orange is another color where white Ekoprime over Ekofill is desired.
    Marty
    N367PS
    Psalm 36:7 "High and low among men find refuge in the shadow of His wing"
    www.marty2plus2.com

  17. #17
    algonquin's Avatar
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    Ok thanks Marty and Bob. I really like working with the Stewart System.
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  18. #18
    Hardtailjohn's Avatar
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    I'd like to see a bigger, better picture of that problem. I can't see much detail from a small picture like you have. I've been using this system since the 90's and have gone through the changes from what it was back then. From what I can see from this picture, I'd be more apt to call out a contamination, especially if you have good results elsewhere on that surface.
    John

  19. #19

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    I'll second John looks like contamination to me.

  20. #20
    Bearhawk Builder's Avatar
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    [QUOTE=Marty57;702302] Urethane over Ekofill isn't in the STC

    I was about to say that EkoPoly is Urethane so what's the problem but I notice that the description of the paint has changed on their web site, it no longer refers to it as Urethane although the name still indicates it's a polyurethane paint and likely is. They seem to purposely avoid the term polyurethane calling it instead a 'high performance topcoat', never noticed this before. I've got some older Stewart's products from 10 years ago or so and it's clearly advertised as a Polyurethane Top Coat.
    What do you know Marty?

  21. #21
    Hardtailjohn's Avatar
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    EkoPoly premium is still a polyurethane.

  22. #22
    Marty57's Avatar
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    [QUOTE=Bearhawk Builder;702331]
    Quote Originally Posted by Marty57 View Post
    Urethane over Ekofill isn't in the STC

    I was about to say that EkoPoly is Urethane so what's the problem but I notice that the description of the paint has changed on their web site, it no longer refers to it as Urethane although the name still indicates it's a polyurethane paint and likely is. They seem to purposely avoid the term polyurethane calling it instead a 'high performance topcoat', never noticed this before. I've got some older Stewart's products from 10 years ago or so and it's clearly advertised as a Polyurethane Top Coat.
    What do you know Marty?
    Both Ekopoly and Ekocrylic top coats are waterborn catalyzed polyurethanes. Ekocrylic is for metal only as it is a harder more brittle top coat and less flexible. Ekopoly is designed for the flexibility needed on fabric and is suitable for both metal and fabric. Both top coats can be color sanded and buffed; Ekocrylic being a bit easier due to it's greater hardness. Both top coats hold up over time to the same standards as tested for the STC's. So, short answer is both top coats are polyurethanes. I guess the confusion is that calling a paint "urethane" is common to solvent based paints as well as waterborn paints. One thing to remember is that Ekopoly and Ekocrylic is not water based; water is the carrier agent for the solids and replaces solvents with mineral water. When most users refer to urethane they are using it in a generic way and referring to solvent based paints. I suspect when a customer refers to urethane they are likely meaning solvent based vs waterborn. Sorry about the confusion on the web site. If you have the newest manual (Rev.#3); section 11 page 2 specifies the top coats as polyurethanes. Long answer here but hope this helps understand the product better.

    Back to original question of the post, I suspect the runs were caused by either the primer being too thin or the gun slowed down for some reason. I've had that happen when I'm not paying attention and pause with my forward motion because the hose is hung up or something is in my way and I have to reach; slowing down my progress.

    Marty
    N367PS
    Psalm 36:7 "High and low among men find refuge in the shadow of His wing"
    www.marty2plus2.com
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  23. #23
    Marty57's Avatar
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    I shot some White Ekoprime on previously sprayed and sanded Ekofill for a seminar I'm teaching this weekend. Thought I'd share settings and results. I'll be shooting Metallic Yellow EkoPrime on both these surfaces.

    Surface prep: Clean with 91% Isopropyl Alcohol on damp synthetic shop towel followed by waterborn paint tack cloth and last wipe with lightly alcohol dusted cloth.

    Gun: DeVilbiss Finishline 4

    Tip: 1.5mm

    Pressure: 58-60psi feed at regulator; 23psi at gun. Air is 13cfm and dry,
    through a dryer set up with three different traps. 3/8" fittings with only quick disconnect is gun.

    Gun Settings: Fan open wide; volume 3/4 turn open

    EkoPrime: Checked from can at 25 seconds viscosity; thinned with a little water in gun. 25 seconds will give a dryer spray that will dry quickly in cool temps. 21 seconds will give smother finish. 25 seconds gives slightly rough finish ready for 400 open coat in less than one hour.

    Application: Medium fog coat; applied 2-3 light cross coats. Purpose of Ekoprime is to lighten up surface for easier color saturation with yellow EkoPoly to follow. This set up will achieve the lightest in weight finish with minimal top coat to achieve proper color saturation.

    Ready to lightly sand with 400 open coat in about one hour.

    Hope this helps figuring out the application of EkoPrime.

    Marty

    IMG_0423.jpgIMG_0424.jpg
    N367PS
    Psalm 36:7 "High and low among men find refuge in the shadow of His wing"
    www.marty2plus2.com
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