Spraying/Sanding Ranthane

Discussion in 'Fabric & Paint' started by bigblackmastiff, Apr 28, 2018.

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  1. Jul 3, 2018 #21

    Don Adamson

    Don Adamson

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    Dan, Are you mixing fresh paint for each coat? I found when painting in the heat or using accelerator it lays down smoother when fresh and not starting to cook off.
     
  2. Jul 3, 2018 #22

    wacoc8

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    I used a regulator at the base of the gun and made sure 40 psi at the gun. 1.3mm tip. I believe that Ranthane recommends 18 seconds on a #2 Zahns cup, which is about 33% thinned. That is a minimum. Open up the fan pattern and the amount sprayed fully. Practice. I used a lot of sandpaper to fix my learning curve.

    Have fun!

    Dave
     
  3. Jul 3, 2018 #23

    bigblackmastiff

    bigblackmastiff

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    Don.
    Thanks, I had about a half a cup in the gun after the mist coat. I mixed more, let it sit for 25 mins along with the mist coat, then reduced. I added this to the gun cup and sprayed the flood coat. I'll plan to keep a fresh mix as you suggest.

    Dave,
    I'll check for 40 at the gun.

    I've been busy wet sanding and getting other sheet metal as clean as i can for primer. With my work schedule it will be a week or so before I get the chance to try more color.

    Dan
     
  4. Jul 11, 2018 #24

    bigblackmastiff

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    Well Eric, You were on the right track on the connectors. The quick connect's valve at the gun was fouling/jambing and starving the gun. I had PSI but no volume. Also my regulator had given up. I tried a cheap regulator from HF while I was hunting for my issue and it lasted about an hour. I've got another in place now.

    You asked about the Gun, Its a SATAjet 3000 HVLP. It has worked perfectly up to this point.

    I've got some wet sanding to do and then I'll see if I've resolved my issues.
     
  5. Jul 11, 2018 #25

    taff

    taff

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    Your gun is probably the sweetest gun ever produced.

    The quick connector will make a huge difference to how the spray gun performs.
    Attaching a photo to show 3 sizes, on the left is your normal HDepot variety (OK for air tools) the others allow higher air volume through.
    If you made an evaluation with one gun and one air gauge, say to show 30psi with the trigger pulled fully
    (it's not important what the gauge reads with static air) with the very narrow connector, you will be starving your spray gun with volume.
    Change over to the large connector and you will need to adjust the gauge until it shows 30 psi, you will also be allowing more air volume through the spray gun.
    Especially important with HVLP spray equipment because they require more (higher) volume of air.

    DSCN8201.JPG DSCN8203.JPG
     
  6. Jul 11, 2018 #26

    bigblackmastiff

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    Copy Eric

    I think it was your advice a couple of years ago that led me to the SATA.

    I bought hi-flow connectors but they aren't as open as shown. I'll look around. It was actually the hose side of the connection that failed me. I was in the habit of having everything connected including the gun before turning the air valve on from the regulator. I hadn't noticed that the valve in the hose end was catching and sitting diagonally across the mouth of the hose, I believe starving the gun.

    Anyway, Hoping that was the worst of it.
     
  7. Jul 11, 2018 #27

    taff

    taff

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    Probably the best place it get high flow quick connector coupler sets would be from Automotive Jobbers. I have never seen them at hardware stores.

    I forget to mention this or maybe you already know.
    Example:
    *Regulator on the wall
    *Hose hard wired to regulator (no quick disconnect. If there is one make sure it is a high flow).
    * Say 50 to 75 feet of air line. (The longer the line the bigger the pressure drop)
    *High flow quick disconnect coupling at spray gun side
    * Mini air regulator with gauge at gun handle (you need this to know what air pressure you will be using)

    This mini air regulator.
    Don't use it to regulate the air going in to the spray gun, use it only as an air pressure gauge. (you can buy non adjustable air gauges only)
    Some call this a "cheater valve"
    Lets say you have 100 psi at the wall and you cheat the air pressure at the gun to 30psi.
    You are also reducing the the volume of air that can pass through because of the restriction you made inside the valve.
    You want this mini regulator to be as high volume as possible.
    So open up the regulator to maximum setting and then go to the wall and reduce the air pressure there until you get the 30psi at the spray gun gauge.
    The wall regulator is capable of pressure reduction without air volume reduction. (rated at a much higher cubic feet per minute [cfm])
    Your HVLP spray gun or any spray gun's performance will improve.
     
  8. Jul 23, 2018 #28

    bigblackmastiff

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    spin.jpg
    I'm starting to think about spraying the color on the fuselage. I'm wondering ...What is the best order/orientation to spray in? ...to dry in?

    The Top of the fuselage has only a short turtledeck, the remainder is sheet metal above the longerons to be painted separately. The Bottom of course seems like the least important surface as it will hardly be seen. I think the fuselage sides must be most viewed and will benefit from being sprayed in the horizontal. I'm not sure if it would be better to leave the sides in the horizontal to dry? or rotate them vertical to show less surface to find dust while drying?

    I'm using a tack coat, flood coat so I'll be rotating the fuselage on stands. I attached a photo just for reference, the fuselage is in white polytone base now, with Ranthane to go.

    Dan
     
  9. Jul 23, 2018 #29

    TFF1

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    If practical, i would want my stop and start to be on the bottom. I personally would want to start on the bottom, work my way up one side, over the top, down the other side to stop on the bottom. Practical is the key word. Simple is I would paint the bottom then do all the sides and top.
     
  10. Jul 23, 2018 #30

    bigblackmastiff

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    Sounds good to me. Two questions.

    1)would you spray each surface while positioned horizontal?
    2)would you leave the fuselage belly up to dry or rotate the sides to sit horizontal?
     
  11. Jul 23, 2018 #31

    TFF1

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    I think thats a personal preference. Seamlessly would be constantly rotating and or moving to the other side only stopping to fill the gun. Many have painted one side and waited. I will say the less reaching the better. Personally, I don't mind painting vertical surfaces. The thing about horizontal is you can put a bunch of paint on that is flat, until you rotate it. Then it will run. If you are doing it horizontal make sure its not going to run if you move it.
     
  12. Jul 23, 2018 #32

    hosspowerinc

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    I start on the bottom, work around the side and top, spray the entry side last, ending on the bottom. I usually leave the bottom up for drying and spray horizontalish. It’s more about lighting and getting good coverage without too much overlap. It’s easy to put too much paint on the tail end because of the taper.
     
  13. Jul 23, 2018 #33

    bigblackmastiff

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    good hints.

    I like painting the surfaces vertical but assumed I'd get better quality if i sprayed them horizontal. So far, dust has been more the enemy than runs, so I think I'm leaning toward leaving the bottom up when finished spraying.
     
  14. Jul 23, 2018 #34

    taff

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    Not so important with the undercoats, like primers.
    But for gloss top coats, it's easier to spray from the top down.
    You can see what your doing and you can somewhat see the reflection of the spray gun in the gloss of the pass of paint you just sprayed (or lack of gloss if it's going on too dry).
    If you start from the bottom, what you just sprayed is clouded in the spray mist that your causing as you work up. The gun and spray mist is between you and the wet paint and it's tough to see how the paint is going on (too much or not enough) .
    When spraying the wings, if they are laying horizontally flat. You should look at an angle until you see the gun reflection or reflection from an over head light or wall window.
    By looking, this is the only way you know how the paint is going on and you must rely on this. This is the only feedback you will have.
     
  15. Jul 23, 2018 #35

    bigblackmastiff

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    18B59283-62AF-4662-805E-DD6B1B0CFD8F.jpeg F3DFC7EF-DA09-4277-BBD2-E4F71F129083.jpeg Latest try spraying the sheet metal. Improving, but this time I had a lot of small depressions as shown at the tip of the pencil. I think I’ll be able to buff these panels and live with the result but I’m curious what I did to cause them.

    I may not have wet sanded heavily enough after my last attempt. That’s my guess. I had gun pressure on the high side (high 30’s), reduced 40%, max fluid, wide fan.

    I’ve been expecting the fabric will be a bit easier than the sheet metal. True or False?
     
  16. Jul 23, 2018 #36

    taff

    taff

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    Doing exactly the same thing one more time in theory, should be easier. As to expecting the fabric will be easier. Of course it will ;) But watch out for corners and sharp edges to the shape of things.

    These examples look very good and virtually no orange peel. If there was orange peel, you probably wouldn't see or notice the fish-eye crater . From these photo's I wouldn't try color-sanding and buffing. You may cause more of a visual problem.
    When these are on the airplane you will never know there is a problem.
    Nice work!
    and sorry about the spelling of crater:mad:
    F3DFC7EF-DA09-4277-BBD2-E4F71F129083.jpeg
     
  17. Jul 27, 2018 #37

    bigblackmastiff

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    Eric (Taff),
    Sent you a PM.
     
  18. Aug 17, 2018 #38

    bigblackmastiff

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    I decided I was not going to get the quality I wanted unless I had a better booth with positive pressure and a good floor. This is about $600 with the plywood, doors, and furnace fan scavenged from Craigslist.
     

    Attached Files:

    Cameron likes this.
  19. Aug 18, 2018 #39

    taff

    taff

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    Dang!
    That looks good and I like the slide in filter at the exhaust.
    It reminds me of a diagonal downdraft booth. So the air comes in at the top and out the opposite bottom.
    In theory this should take the fumes and the overspray down towards the ground and less in your face or on the parts your spraying.

    One thing, replace the exhaust filter at the first sign of clogging up.

    One other thing, After spraying something, keep the fans running.
    If you don't then the solvents stagnates or linger in the booth and this will retard drying and maybe give solvent pops or low gloss to your top coat.
    As soon as the paint is good to "touch dry" (touch the paint and it should be resistant to light finger damage) you can close down the fans and open up the doors if the outer room is draft free.
    Solvent has to leave for the paint to start curing correctly.
    All the best with your booth.
    I forgot to ask, what are the cfm ratings of the fans. The exhaust looks a little small?
     
  20. Aug 18, 2018 #40

    bigblackmastiff

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    Taff,
    I don't know the rating on the intake (furnace) fan. It has three speeds if you open it up and wire it as needed. It is set to high and pushes a lot of air. It is actually difficult to latch the 18" man door with the fan going and it does keep positive pressure with the door wide open. You can see the plastic bulging up, etc.

    I'm thinking the same about the exhaust (small), but I want to test a little before making any changes. The exhaust fan is rated at 1590 CFM, and I'm sure I'll lose some as I'm pushing the exhaust out of my building via a flex hose. I will consider using an inline fan in the flex hose or another filter/fan in parallel if I can't clear the overspray.

    The formula for a "real" booth would require 8000cfm. I know I won't even be close but in comparison to my last setup I know I am way ahead. I'll report back when I paint something. Its wet here this week.

    I have bought some LED fixtures as well and will get some light setup while I wait for a drier day.

    Dan.
     

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