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Drips and Sags.......

Discussion in 'Finely Finished' started by boneyguy, Oct 31, 2020.

  1. boneyguy

    boneyguy Doctor of Teleocity

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    For this particular project I'm spraying an acrylic 2K auto finish. I normally use nitro. I've got 5 coats on from a week ago that have been sanded with 800 just to knock back any dust nibs etc. I spray outside so I've been waiting for appropriate weather and time to do this.

    I just went to spray a few more coats and the 1st coat went on too heavy and now I've got some sagging and a couple of runs.

    So, is it best to let it cure and deal with the problem or is it okay just to keep spraying and fix it when I've got all the coats on that I want.

    Personally, I don't see any real issue with continuing to spray. Of course it means the sags and drips increase in height but then so does the rest of the painted surface. No harm, no foul, right?

    What are your various opinions on this? How do you normally deal with sags and drips?
     
  2. eallen

    eallen Friend of Leo's Silver Supporter

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    Let it cure and block sand them out. Just adding more on top will only layer more to deal with later.
     
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  3. boneyguy

    boneyguy Doctor of Teleocity

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    Yes, that's true, and I'm guessing that's the conventional wisdom from those with much more experience than I. However, I can't help thinking that the relative difference in height between the sags/drips and the surrounding paint will remain the same regardless of how many coats I put on, no? As the sags/drips increase in depth so will the surrounding areas by the same amount meaning that there won't really be more to level if I keep spraying.

    Is this logic flawed?
     
  4. trev333

    trev333 Telefied Ad Free Member

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    I paint my bodies on the flat/horizontal.... stops any sag/drips.... any edge drips are easier to deal with than on the flat top/bottom...

    2K you'd need to let cure before sanding maybe?...
     
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  5. eallen

    eallen Friend of Leo's Silver Supporter

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    Yes, the goal on your final coats is to use as fina grit as possible to sand with minimal sanding, or none, before buffing. When you leave the runs you end up using coarse grits with deeper scratches to sand out. But, since it isn't mine to deal with the choice is all yours!
     
  6. boneyguy

    boneyguy Doctor of Teleocity

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    Thanks.
     
  7. Freeman Keller

    Freeman Keller Friend of Leo's

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    I only do lacquer but I do get runs and sags. I let them dry overnight and level them before shooting any more. Lacquer of course burns in to previous coats, I don't know what your finish is doing. If it doesn't burn in I would worry about witness lines (which is why I quit experimenting with water born finishes and went back to solvent).

    I've mentioned this on several other posts lately about orange peel and such that I divide sanding into two parts - 320 dry for all the leveling up to the last coat and 800 or 1000 wet after the last coat. And I agree with Eric, I want to do the minimum sanding on the last coats before buff.
     
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  8. boneyguy

    boneyguy Doctor of Teleocity

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    I've done lots of nitro, if that's what you specifically mean by lacquer, but this project, for various reasons, needed another finish mostly for it's non-yellowing and very hard, durable qualities.

    320 seems so coarse to me for any use on a finish. I know I've read many times that people use 320 but frankly I still classify it as a relatively coarse paper and I've never understood how 320 can be used without sanding through.

    I have a very good procedure worked out for levelling and polishing....I've figured out a way to get a 'factory finish' without a buffing wheel. The real secret is the buffing pads I've found to use with my RA sander. It turns out like candy. No swirls or any evidence of polishing.

    Anyway, I've stopped spraying for today and I'll deal with the problems tomorrow.
     
  9. telepraise

    telepraise Tele-Afflicted

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    Acrylic is a whole nuther universe, it's not going to melt into itself I assume, and if it sits for than an hour or so, you have to scuff sand to get a mechanical bond. At least the catalyzed finishes I use work that way. So definitely level the runs and sags BEFORE you add more coats, otherwise, when you finally do level sand and recoat, you'll end up with witness lines that look like a topo map. Nitro really is more forgiving in that respect.

    Acrylic is hard enough you can probably scrape those runs too. Use a fresh utility knife blade with the tape safety guides on each end. 320 grit is absolutely appropriate for in between coats. Much finer grit leaves not enough tooth in the finish for the next coat to bond, especially with a non-burn-in synthetic.
     
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  10. boneyguy

    boneyguy Doctor of Teleocity

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    I was considering scraping the couple of runs rather than sanding....and yes, I will do a scuff sand before spraying anymore coats....these were always part of the plan.

    The 2 part acrylic universe is not my preferred choice although I do have some experience with it using a rattle can product called SprayMax 2K which I can highly recommend if you have a situation where you want a very tough acrylic finish. Currently, however, I'm mixing the catalyst into the resin myself. This stuff flows out and levels so beautifully...I made the mistake of laying it on too heavily....my gun wasn't setup quite right on the first coat.

    My OP was seeing how other people might deal with this situation. So, it's hanging up and I'll scrape/sand tomorrow.
     
  11. Kevin Wolfe

    Kevin Wolfe Tele-Meister

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    If you don’t mind, I’d love to hear more about your “very good procedure”. I’m trying to learn all I can.
     
  12. boneyguy

    boneyguy Doctor of Teleocity

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    Most of the procedure is what is typically done of course....the levelling...I usually go from 800 to 1,500 wet sanding. I use Meguiar's automotive polishes....so, nothing noteworthy there. The thing that I've discovered, as no doubt some others have too, is a polishing pad call Surbuf. It's magical!! It's a hook and loop attachment for random orbital sanders. So, for example the last two things I painted were a Tele and a Strat neck for a buddy. I wet sanded only to 800 on the Strat neck and then used a medium compound and then a Meguiar's compound for taking out swirls and tiny scratches on the Surbuf pad...two pads kept seperate for each compound. That neck looks like a piece of candy...it's flawless. I held it up multiple times to natural light and artificial light from all sorts of angles and there are no polishing marks at all....no haze under a glossy surface effect that can happen. It's flawless as far as I can tell. I have a brand new Allparts neck that I'm using for a project and it doesn't look nearly as good as the one I painted. So, the real star of the show are the Surbuf pads.

    https://www.surbuf.com/Surbuf-Buffing-And-Polishing-Pads.asp
     
  13. Peegoo

    Peegoo Poster Extraordinaire

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    If you scrape, you risk pulling too much finish out of the slightly softer areas in the drips.

    I've rescued several finish jobs by spot-leveling the drip/run using a smooth file. Yep, a file. Here's how I do it.

    Use a small thin single-cut smooth file. I prefer a short 6" ignition file, and I use it only for this operation so it stays nice and sharp.

    Make sure the file is as flat as possible. If it has a slight curve to it, use it with the convex side facing up. Apply a single layer of Scotch tape to each end of the file, and leave about 2" of file teeth exposed in the middle. This tape rides on the surface of the finish as you press gently with a fingertip in the center and take light forward strokes in one direction only. Scrub the file with a small brass or steel brush to keep the teeth clean after every pass. It goes pretty fast. No need to use water or other lubricant because this does not build heat on the surface.

    Monitor your progress by looking at the reflection of an overhead light in the surface; you'll see when the file has planed the drip/run flush with the surface.

    I use this technique far more often when leveling a drop-fill; it results in an almost glass-smooth surface that requires only light polishing to blend it into the surrounding finish.

    Note: this works well on flat surfaces only. If you're correcting a drip on a convex or concave surface, use extreme care.

    [​IMG]
     
  14. Peegoo

    Peegoo Poster Extraordinaire

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    Yet another way is to strip sand the drip. Cut a piece of 320 or 400 3"-4" long and 3/8" wide. Pinch one end of the strip between finger and thumb, and use a fingertip of the other hand to gently press the grit side of the strip against the drip. Holding this finger in place, gently pull the strip from under the finger.

    Randomly alternate the angle that you pull the strip over the drip. For example, if the first pull is to the 9 o'clock direction, make the next one to 7 o'clock, and the next one 10 o'clock, etc.

    The idea here is to think of this process as sort of a mini belt sander--and that's exactly how it works. The tip of your finger will 'feel' the surface smooth out as you work. This method does usually require following up with a small block to wet-sand the area.

    A really good mini sanding block for this purpose is one of these. Fold your paper over the bottom and grip each side to hold the paper in place:

    [​IMG]
     
    Last edited: Nov 1, 2020
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  15. boneyguy

    boneyguy Doctor of Teleocity

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    I got the drips and sags level using 400 with a variety of small blocks and fingertip. On the larger drip I used painters tape to isolate it and create a barrier so I wouldn't sand into the surrounding area. Once I got it level with the tape, I removed the tape and levelled it with the surrounding paint.

    Other than my own little missteps in painting what is making this project VERY challenging is that the surface I'm painting is not smooth. I'm doing a series of Teles that I've enlisted a well known local First Nations artist to paint. Her paintings have been exhibited all over the world. The bodies are made of local red cedar, which itself presented a few challenges. The painting is done with artist's acrylics and brush...there is also abalone inlay and on some there is also some shallow carving. So, I am being challenged by this I can tell you!! Obviously I need to apply enough clear so that I can level sand without going into the painted artwork...so, it's going to take more coats than would normally be the case. I'm leaving the abalone expose without any finish. The reason for choosing the acrylic 2K finish is because it does not alter the colours in the artwork and it's extremely tough to protect the artwork. But, boy, is this presenting a challenge!!
     
  16. Freeman Keller

    Freeman Keller Friend of Leo's

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    Sounds like an interesting project. Please post pictures when you are finished.
     
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  17. boneyguy

    boneyguy Doctor of Teleocity

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    I'll do that for sure! It will feel like quite an accomplishment when I'm done...lol. The artist is growing impatient...she has no idea what I have to do on my end of this collaboration. It's requiring far more clear coats than I anticipated but I'll get there!
     
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  18. UPtele

    UPtele Tele-Meister Gold Supporter

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    Are you using spraymax?

    I had a few minor runs with it that I was able to blend out with the spray
     
  19. boneyguy

    boneyguy Doctor of Teleocity

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    I've used Spraymax a couple times in the past...great product. This time I'm mixing my own. Although I really prefer using nitro I have to say that this acrylic 2K stuff is very nice to use...it lays down and levels very nicely and it's cured in 48 hours or so, ready for levelling and polishing.

    Because I was worried about sanding through into the artwork when dealing with the sag and runs I got them out over several coats. I first used 400 which seemed just right. I sanded them down but not flat...sprayed another coat and did the same. I've now sprayed another coat and the sag and runs are gone.
     
  20. boneyguy

    boneyguy Doctor of Teleocity

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    Here's a few pics I took this morning. I've got to get a few more coats on it but it's starting to take shape. The control plate and pickup ring I made out of some exotic hardwood I had laying around. It's been quite an undertaking. Red cedar presents some challenges I wasn't expecting.
    I sent these pics to the artist this morning and she was very happy, so that's good. The green circles are the abalone inlays I've taped off. I'm leaving them raw and unlevel.

    DSCF1184.JPG DSCF1192.JPG DSCF1176.JPG
     
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