Help with Spray Polyurethane Finish, please

NecrosisFactorG

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Hi folks! I'm a newbie trying to make my first paint job. Bought an individual Telecaster body (of an unknown wood) which i didn't sanded/grain filled/ primed properly, but with almost good results. I used Rust-Oleum 2k white primer and grape gloss 2k paint+primer for my base color coat. After 6 grape gloss coats i ended up hating the color LOL. Then i moved up and sprayed a Krylon ocean breeze acrylic enamel over the body with excelent results. I just waited a week or so for the paint to dry/cure with a heater and a fan on my room, but didn't passed the fingernail test (it's raining a lot outside). Because i'm very impacient, i bought yesterday a Behr Oil based polyurethane spray can and started with the finish, wet sanding with 800 grit and applying a thin coat of poly over the body (too thin, i guess, because it did look wet and almost shiny but with a rough texture, like if the paint fell like dust onto the body), then applied another 2 coats with 1 hour between. Those coat attempts were regular, with shiny and wet spots but i didn't care too much because today (24 hrs.) i did the wet sanding again with 800 grit (i left some little shiny spots were the grain wasn't properly filled up) and sprayed the poly again. 3 coats today, and the last one have this rough texture. I know that sprayin' poly on a can is a pain because of the thining agents and the fact that most of the paint is dry before it gets to the surface, creating this rough texture. My questions are:

- Do i need to spray closer? (my first attempt doing this made some ugly run which i fixed up today)
- Can i achieve a high gloss if my final coat have this texture? I mean, wet sanding with 800/1000/1500/2000/2500/3000 and polishing compounds?
- How many coats would you recommend? i don't like very thick poly finishes but i know it must be thick enough for the polishing process
- Am i screwing up everything since the begining? :(
- Since the Behr poly can is already empty, should i try my luck with Minwax oil based poly spray or i need to stick with the same brand?

Until now, there aren't any wrinkles or weird chemical reactions...

Thnx a lot and sorry in advance for any head itchiness my paint mistakes could cause on you :D.
 
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NecrosisFactorG

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Some pictures...


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dogmeat

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its too dry. need wet coats, but that can be tricky. I'd give it a couple days to cure then either sand it smooth and compound it (if the color coat is thick enough) or sand off the big boogers and clear coat it. I would stick with same brand if I were you.
 

NoTeleBob

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This ^. Yes, wet sanding carefully through the grits will get you to a nice flat finish. Be sure to stop with a grit a little early. Very little #400. Not much with the #600. almost "wiping" by the time we get to #800. If you're at 800 and there are still significant variations, perhaps use some lower grit again, but be very careful. Work you way up to smooth.

Don't change brands of paints. Stick with what you have. You never know when two finishes might not want to play together.
 

Peegoo

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Mist coats are good--but only when you are shooting from a gun and can thin out the finish so it flows. From an aerosol can, mist coats create that 'orange peel' you're getting in the cured surface finish.

To get a nice even coat with a spray bomb, you must lay on a wet coat so it flows and self levels. This is tricky because the amount of finish you apply to self level is a split second short of applying too much and getting a run in the wet finish.

There's a trick to doing it, however:

Work in an area with very bright overhead lights, and hold the guitar body (mount it on a stick where the neck goes) so you can see the reflection of the lights in the wet finish as it's going on. Watch the reflection, and when it creates a complete picture of the overhead light, move to an adjacent area and repeat. You have to work fast because the solvents in aerosol finishes flash off pretty quickly and the finish tacks up. Keep the body moving so gravity doesn't pull all the wet finish downward. It's a sort of a dance.

Obviously you can shoot finish with the body hanging stationary, but shooting a self-leveling coat is nearly impossible this way, and it means you'll be wetsanding a whole lot more.
 

trev333

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My aim with poly is to get a great finish off the can and never sand polish.....

or wait 12 mths then sand polish...... gotta be nice and hard.

it's a different animal than acrylic/nitro lacquers.... one shot baby...:D


carbathane1.JPG PIC_0156.JPG
 

NecrosisFactorG

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Thanks a lot for everyone's great help!

Mist coats are good--but only when you are shooting from a gun and can thin out the finish so it flows. From an aerosol can, mist coats create that 'orange peel' you're getting in the cured surface finish.

To get a nice even coat with a spray bomb, you must lay on a wet coat so it flows and self levels. This is tricky because the amount of finish you apply to self level is a split second short of applying too much and getting a run in the wet finish.

There's a trick to doing it, however:

Work in an area with very bright overhead lights, and hold the guitar body (mount it on a stick where the neck goes) so you can see the reflection of the lights in the wet finish as it's going on. Watch the reflection, and when it creates a complete picture of the overhead light, move to an adjacent area and repeat. You have to work fast because the solvents in aerosol finishes flash off pretty quickly and the finish tacks up. Keep the body moving so gravity doesn't pull all the wet finish downward. It's a sort of a dance.

Obviously you can shoot finish with the body hanging stationary, but shooting a self-leveling coat is nearly impossible this way, and it means you'll be wetsanding a whole lot more.


Wow, that's exactly what my problem is! I've been shooting spray cans with the guitar hanging vertical all this time.. Not to mention that light is a big problem because most of the time can't see where i'm painting. I will try to make a stick for it and vertical painting. Thanks a lot!
 

dogmeat

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and by the way.... do not spray the big flat areas first. cut in the sides, corners, and details first. you do all the cuts first because the overspray that ends up on the big flats will be buried when you the easy parts

one of the downsides to rattle can is there is no way to change viscosity other than warming up the can... might try that. experiment by warming the can up in a pan of water with a thermometer. prolly wouldn't go more than 100-120F
 

NecrosisFactorG

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and by the way.... do not spray the big flat areas first. cut in the sides, corners, and details first. you do all the cuts first because the overspray that ends up on the big flats will be buried when you the easy parts

one of the downsides to rattle can is there is no way to change viscosity other than warming up the can... might try that. experiment by warming the can up in a pan of water with a thermometer. prolly wouldn't go more than 100-120F

Yes, i always start on the sides and corners first (and that's probably why those parts get a nice wet coat). As for the can warming, i thought it was only good for lacquers but i'll totally give it a shot, thanks a lot! I'm gonna leave it almost 4 days to dry and do everything said here.
 

NecrosisFactorG

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Btw, it's kinda strange that krylon's ocean breeze color looks greenish on person. Almost like a surf green, but on pictures looks totally blue :lol: i hope the oil based Poly helps getting the greener color
 

DrASATele

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I definitely think those above me hit the nail on the head. Too many different brands and types of finish is likely your issue. Rustoleum and Krylon are likely similar but since they are 2 different paint companies I bet the solvents are slightly different and likely the issue you are having. Then add in Polyurethane, over enamel and starting over is likely a good idea at this point. Lose the polyurethane if you are locked in on that enamel color. Use the clear coat from the same brand (and type of paint) as the color coat, do not use another brand or switch from say 2X Rustoleum to Rustoleum Max Cover ...2 completely different types of paint, guess how I know that . . . any who.... if you switch over to lacquer, that's where IMHO, things get a little better in terms of compatability, I've used watco and behlens together, even used the Rustoleum White Lacquer under both watco and belhens…. I did find out recently that the minwax lacquer has changed in the last few years and is not compatible with what I mentioned above. Good luck!
 

NecrosisFactorG

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I definitely think those above me hit the nail on the head. Too many different brands and types of finish is likely your issue. Rustoleum and Krylon are likely similar but since they are 2 different paint companies I bet the solvents are slightly different and likely the issue you are having. Then add in Polyurethane, over enamel and starting over is likely a good idea at this point. Lose the polyurethane if you are locked in on that enamel color. Use the clear coat from the same brand (and type of paint) as the color coat, do not use another brand or switch from say 2X Rustoleum to Rustoleum Max Cover ...2 completely different types of paint, guess how I know that . . . any who.... if you switch over to lacquer, that's where IMHO, things get a little better in terms of compatability, I've used watco and behlens together, even used the Rustoleum White Lacquer under both watco and belhens…. I did find out recently that the minwax lacquer has changed in the last few years and is not compatible with what I mentioned above. Good luck!

I think that the Rustoleum thing is out of the equation since it was sanded out before spraying the Krylon. Applying Lacquer instead Poly is going to result in a real mess lol. The Rusto and Krylon paint cans are acrylic and polyester enamels. Rust- Oleum clear coat isn't Lacquer, it's just an enamel transparent clear. I'll stick with Poly because it's more an Orange peel and dry coats thing more than differences on brands. Thanks You!
 

schmee

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This is a bit of a caution comment: I discovered not to mix brands the hard way. I built a 5E3 head once and made a simple wood cab. I decided to just spray the cab the same aqua color you have on that guitar. Unfortunately I mixed brands from a primer to the aqua. It never got hard. It's been years but that mess is still out there and still gummy.
 

NecrosisFactorG

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This is a bit of a caution comment: I discovered not to mix brands the hard way. I built a 5E3 head once and made a simple wood cab. I decided to just spray the cab the same aqua color you have on that guitar. Unfortunately I mixed brands from a primer to the aqua. It never got hard. It's been years but that mess is still out there and still gummy.

Sorry to hear that! :( i really didn't want to mix brands but the ones that i could find only had few color options. I know that driying isn't the same as curing and that i didn't wait for the color paint to fully cure, so i hope the Poly doesn't crack or anything from now on. Thanks for the advice!
 

NecrosisFactorG

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Well! I applied the last 3 clear coats (something like 10 coats in total). It's been driying for almost 4 days and it still smells like chemicals but i barely leave a small mark on the fingernail test. I know it isn't cured for this little period of time, but can i buff and polish it in maybe, 1 day or 2? Thanks!
 

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NecrosisFactorG

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The data sheet says it would be fully cured in 72 hours..
 

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Dismalhead

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Meguiars Mirror Glaze, I do a medium cut and then ultra-fine. The key is putting on multiple coats and then polishing it to a super gloss. You can do it by hand or you can use a buffer. I sit in front of the TV and do mine by hand slowly over a few weeks.

This guy is all Rustoleum:

ffLXJuu.jpg
 

NecrosisFactorG

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Meguiars Mirror Glaze, I do a medium cut and then ultra-fine. The key is putting on multiple coats and then polishing it to a super gloss. You can do it by hand or you can use a buffer. I sit in front of the TV and do mine by hand slowly over a few weeks.

This guy is all Rustoleum:

ffLXJuu.jpg

Whoa that's a beautiful paint job right there!
But i don't think i could find Meguiars products in my country. I've already bought this unbranded polishing compound from an automotive paint it says "pink" and they told me it was a medium grain compound. I can find 3M compounds a little bit expensive but the have all grain levels available.
 




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