Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com
Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com
Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com

First Build Issues

Discussion in 'Finely Finished' started by mikeyj, Sep 13, 2017.

  1. mikeyj

    mikeyj TDPRI Member

    Age:
    52
    4
    Sep 13, 2017
    Scotland
    Hi,

    Just signed up after a bit of lurking - gathering some of the excellent info available here.
    Over the summer I've been working on my first build - a cheap jazzmaster style kit.
    I've reached a point where I'm not sure of my next move.
    Its been sprayed with BIN white primer / filler, wet sanded, then sprayed surf green nitro from a rattle can (Northwest Guitars in UK).
    The surface is now rough, as can be seen if you zoom into the attached pics. In addition there are some spots visible, blobs of paint spat out of the can?

    I think the options are: 1. wet sand and hopefully avoid going though to primer, 2. continue with the process and spray clearcoat that will level out the roughness, 3. spray more colour make sure to get proper wet coat, then continue to clear.
    I'm not sure which of those is the best way to go, or maybe there's another better solution.

    Any advice would be greatly appreciated.

    M.
     

    Attached Files:


  2. Silverface

    Silverface Poster Extraordinaire Ad Free Member

    Age:
    65
    Mar 2, 2003
    Lawndale CA
    With lacquer you do NOT normally wet sand the color! That's usually a disaster in the making. At most sand runs and splotches that are seriously bad.

    Then you have a decision. If the whole thing is as bad as you seem to be implying (the pictures are not very accurate - you need full lighting - not bright in a spot and weak in others - and preferably figure out how to have the color correctly represented - for a couple of reasons) you have two choices (after "fixing" serious goofs):

    1. Apply a couple of clear coats and see what you get. They will melt into the color coats and either level things out - or not. If not, cut your losses, strip it and start over

    or -

    2. Wet sand it until smooth...or strip it...and start the color application over from scratch.

    BUT - the big question is why is it so lumpy/bumpy, inconsistent in the first place? Ideally you should have stopped after one or two color coats and reevaluated your spray technique or ambient conditions at that point.

    Questions:

    What is the ambient and surface temperature? Humidity level?

    Were all "coats" applied by making 3 light passes (not full coverage passes) per coat? How many "coats" were applied (dry time between is not an issue if 2-3 are applied per day correctly and in good conditions).

    What was 1) the position of the piece, 2) the angle of the spray can during application, and 3) the distance

    Was the trigger FULLY depressed at ALL times?

    Was the trigger pressed before it was over the piece and released after it had passed? Was there any "waving" over the piece?

    Was the nozzle kept at a consistent distance by moving across the piece (i.e. no "golf swings" where the center of the "pass" was closer)?

    How much material was consumed on the piece - and how much on the practice scrap piece?

    Did the practice piece show the same problems? If so why was the same process used on the actual guitar?

    I realize there are a lot of questions - but it's kind of baffling how it could get to that point. Color coats normally go on very smoothly with only some hairs or tiny runs to fix before clear coating; clear coating should rarely need sanding, other than maybe some wet sanding with 1000 and finer just to "fine tune" things. Usually things should be ready to be buffed instead.

    But even when things are a little less "correct" problems are caught much, much earlier. If you aren't sure how to apply the materials - well, that's what the practice piece is for, and why the whole system is applied there before ever starting on a guitar for exactly these types of reasons.

    Anyway - if you can fill in the blanks on the questions let's see if we can figure out what to do!
     

  3. mikeyj

    mikeyj TDPRI Member

    Age:
    52
    4
    Sep 13, 2017
    Scotland
    Hi Silverface,

    Thanks for the very detailed response. I will get some better pics uploaded later, and have answered the questions below:

    What is the ambient and surface temperature? Humidity level?
    A: Weather history site suggests temp between 15-20 deg C, and humidity 60%. Was dry sunny day here, not very warm, no breeze, hadn't rained that day.
    The guitar was sprayed outside in the garden.

    Were all "coats" applied by making 3 light passes (not full coverage passes) per coat? How many "coats" were applied (dry time between is not an issue if 2-3 are applied per day correctly and in good conditions).
    A: That's what I was trying to do, 3 passes, one coat. I could see that I wasn't getting any obvious wet look. I had previously applied a coat about a week earlier which wasn't rough like it is now, but wasn't smooth like the wetsanded primer underneath.
    Each time the can was sat in bucket of warm water then shaken for easily 5 mins before starting, and back in the water plus some shaking between doing front and back.

    What was 1) the position of the piece, 2) the angle of the spray can during application, and 3) the distance
    A: 1. Hanging by wood attached to neck, centre 4-5ft off the ground. 2. Perpendicular to guitar body spraying in horizontal passes (One of the passes on 2nd coat was done vertically - thought it might give more even coverage.) when doing front and back, sides a bit more freeform. Could spraying sides / edges have caused light spray across the face of the guitar resulting in unevenness? 3. About 8" - 10" away.

    Was the trigger FULLY depressed at ALL times?
    A: I believe so.

    Was the trigger pressed before it was over the piece and released after it had passed? Was there any "waving" over the piece?
    A: Sprayed to the side before passing over the body, sometimes with the trigger held down going past the other side then back without releasing the trigger.

    Was the nozzle kept at a consistent distance by moving across the piece (i.e. no "golf swings" where the center of the "pass" was closer)?
    A: Distance was kept consistent.

    How much material was consumed on the piece - and how much on the practice scrap piece?
    A: One 400ml can, giving basically two coats. I could see a lot of it disappearing in clouds even with no discernable breeze.
    No scrap practice piece. Basically due to price of spray cans here. Its a cheap kit so treating the whole build as practice.
    I know, no amount of reading here and watching you tube videos will make up for lack of practice, practice, practice.
    I did think I knew what to do, so hopefully getting it wrong will teach me how to do it right.

    Thanks,
    M.
     
    El Tele Lobo likes this.

  4. Silverface

    Silverface Poster Extraordinaire Ad Free Member

    Age:
    65
    Mar 2, 2003
    Lawndale CA
    OK, let me go point by point and see where we get. You'll want to print this for reference.

    1. Humidity was pretty high. Right on the edge of "don't coat". But unlikely to cause your issues. OTOH if you saw any even slightly foggy areas you have a blush issues that needs to be addressed. Temperature looks OK. But it is possible both were actually higher unless you checked it in the garden. If it's a crowded garden and/or enclosed area both temperature and humidity will nearly always be much higher. If so the temperature could prevent good flow of the material - even efficient spray as the lacquer can begin to dry in the air.

    There's no need to warm the material under the ambient conditions. That can actually cause problems if the water is too warm. Shaking for one minute after the "ball" is loose should be plenty. Don't sprain your arm.;)

    2. Now the problem is obvious - the first coat (and those individual passes) shouldn't fully cover. If it had looked smooth and wet you'd have had a huge problem on your hands at a later date! Even a second coat (another 3 passes) rarely covers completely.

    Two coats is not enough if applied correctly - and if you used up the entire can (even close ) applying 2 coats each coat was applied WAY too thickly.

    Three things can occur when lacquer is that heavy (one or all) - 1) Runs; 2) inconsistent, lumpy/bumpy looking surface like large orange peel; and/or 3) solvent entrapment: the material dries on the surface - sometimes forming a hard film that feels normal.

    But tiny pockets of solvent are trapped underneath that can't escape. Yet. They will eventually create small bubbles, larger blisters, and/or cause the coating to peel. This can look like delamination within itself or as if it didn't adhere to the previous coat. It can happen right away, at a random time when the surface gets warm, or cause early, otherwise unexplained chipping.

    To get reasonably smooth, void-free color takes 5-6 coats (a really good pro might nail it in 4 - but there's no reason to). And normally there will be material left - usually enough to have done a small but full test run on scrap. (but I always recommend having at least two cans of everything on hand to handle a larger test and "just in case"...)

    ***If the pictures represent only two coats the material is on *way* too heavy. You can figure each pass should have been less than half as "full" as was actually applied.

    The usual cause is moving too slowly & trying to "cover". That's not the goal. A pass across a body - if you're at roughly 12" and perpendicular (very important) should take about 2 seconds. Or less. It depends on the material used and the type of spray nozzle - but when in doubt faster is better. It's OK to spray a bunch of really light coats - it's not OK to spray only a couple of heavy ones and consume all the material - or close.

    3. Part of the reason for that is - as mentioned earlier - applying the entire system on a piece of scrap before ever touching the body. this means preparation, sealers, fillers, primers, color coats, tones, clears and polishing. By doing this you'll know what to expect and can ask questions about problems that come up before ever touching the actual guitar. Even professional finishers do full system test applications before starting a job with new materials (even an never-before-used brand of a "normal" product).

    Testing just one of the components only tells you how it sprays, or rubs, or brushes (and with a couple how they sand or polish) - not how it actually covers over (or even under) another component or how the products interact.

    A test piece would have "flown" a red flag as soon as the first color coat was applied.

    onwards -

    4. 8-10" is too close for aerosol lacquer. It's fine for an HVLP gun, but aerosols provide such minimal control 10-14" is better. I recommend no closer than 12". At a distance of " each pass would need to take less than a second and the material still would be inconsistent.

    5. Never spray sides last. It causes inevitable overspray on the most visible areas of the guitar body. While it's technically OK to apply the color coats that way )(since clear will still bne applied) it's better to stay consistent. Do sides first, the back, then top. Always the most-seen area last. Trigger use and moving past the body seem OK -

    The fix: 1) Strip or sand ALL the color coat off. Don't leave any at all - because of possible solvent entrapment you could end up with all sorts of complications. If it was just lumpy - but after 5 or 6 coats - it would just need leveling. But as mentioned thick application almost always traps solvent. It also can be far more difficult to sand smooth as the lower portions are not as dry (even though it seems OK).

    Then 2) start over. Sorry. There's no way to "save" it as you're out of color and sanding it smooth/consistent is virtually impossible at this point.

    OK, cheap kit or not - step up to the cash register. Here's the conundrum - you could have paid for enough material to 1) practice and 2) to coat it, with enough material left over just in case; or paid for 1) the material that already went on wrong, and 2) enough to practice plus 3) enough to coat it, with enough material left over just in case. 1+ 1 should have = 2. But 1 plus 1+1 = 3.

    Lacquer isn't any more expensive there than here unless you're having special guitar lacquers shipped from the US. All guitar-specific colors, though, are made in small batches and are more expensive than "hardware store" lacquers - mo matter where you get 'em.

    Ooops. o_O

    Instead of 2 cans each of color and clear you're going to need at least 2 more of each - and probably 3 of clear. Seriously, 2 *might* be enough for the body with a little left over.

    Correct application notes:

    Remove the color coat, sand smooth - then put the body in a box so you won't be tempted to touch it until you have completed a decent-size piece of practice material and it looks good.

    Color coats go on thin. You can do 2-3 per day and be done in 2 or 3 days with that part (it can go faster but I don't recommend it. Go slow). the last color coat should get you a nice, smooth...sorta, but not necessarily perfect - surface with full coverage. NOT orange peel nor "dusty" or sandy looking (the former = too heavy; the latter two too "dry" your spray). The clear will melt into the color and do at least some leveling.

    NEVER sand the color coat - you can "touch sand" small runs, areas with dust or hair removal etc - but those require at least one additional pass over that whole surface.

    When the clear - anywhere from 5-10 coats (again, 3 passes each and a couple coats a day) are what I recommend for good color depth, gloss and durability - is applied it should be very level and smooth, with good gloss. The last coat - the last 2 if you got them to work this way on the test piece - is applied a bit heavier to get aa bit of "flow out" - a smoother, even surface.

    The idea is to be able to go straight to buffing - no sanding short of a very few tiny runs again. If the whole thing needs wet sanding with anything more coarse than 1000 the application is too rough.

    Hope that helps. It's a bummer, but live & learn!
     
    old wrench likes this.

  5. mikeyj

    mikeyj TDPRI Member

    Age:
    52
    4
    Sep 13, 2017
    Scotland
    Hi Silverface,

    Thanks yet again for your very detailed and helpful response. This info will hopefully get me doing the job right next time.

    A couple of things I remembered, but not really relevant now you have diagnosed the problem:
    There were no foggy areas, so no blush issue.
    I doubt the temperature was even 20 and the garden is quite a big open space.
    There was a dry dusting of colour at some parts that could be blown off.
    The nozzle got blocked a few times, shook it in the water to unblock, sprayed a bit into the air to clear it.
    Shaking and warming - I was trying to make doubly sure it was well mixed to prevent it going wrong...

    A week or so before the two sets of three passes I had done a very light initial coat that seemed ok - a hint of green over the white primer.
    I'd forgotten about that.
    So if I'd continued like that it would have built up properly and been ok, although another can of colour would have been needed anyway - also to do colour headstock.

    You had requested a couple of better pictures, again maybe a bit late, but they're attached anyway.

    I should be getting an Earlex hvlp sprayer soon for some fence and decking work, and noticed that another uk member uses one of these for spraying guitars, so I might get some laquer for that and practice a bit before going near the guitar body again.
    I'll have a search and pm them to see which model they use.

    Thanks,
    M.
     

    Attached Files:


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