spraying a guitar body with car paints/varnish?

GoldenEraGuitars

@mikem8634 what have you sprayed the body with?

mikem8634

GoldenEraGuitars said:

@mikem8634 what have you sprayed the body with?

This - https://www.montanacolors.com/en/productos/varnish-water-based/

I haven't got a clue what 'dry but not cured' should feel like. Or how long to wait to see if it improves before calling it and starting again.

GoldenEraGuitars

mikem8634 said:

GoldenEraGuitars said:

@mikem8634 what have you sprayed the body with?

This - https://www.montanacolors.com/en/productos/varnish-water-based/

I haven't got a clue what 'dry but not cured' should feel like. Or how long to wait to see if it improves before calling it and starting again.

Did the body have anything sprayed on it before this was used?

mikem8634

GoldenEraGuitars said:

mikem8634 said:

GoldenEraGuitars said:

@mikem8634 what have you sprayed the body with?

This - https://www.montanacolors.com/en/productos/varnish-water-based/

I haven't got a clue what 'dry but not cured' should feel like. Or how long to wait to see if it improves before calling it and starting again.

Did the body have anything sprayed on it before this was used?

No, nothing sprayed but they were decorated with Posca Pens by my nieces. My thinking was to stick with water-based products.

GoldenEraGuitars

It sounds like some sort of compatibility problem. Obviously it’s not possible to know without doing a test myself but the finish should have dried by now imo.

mikem8634

GoldenEraGuitars said:

It sounds like some sort of compatibility problem. Obviously it’s not possible to know without doing a test myself but the finish should have dried by now imo.

Ahh right that's not good. I might do a quick test of the same products on a bit of scrap, but it's looking like sanding down and starting again may be the best bet. Cheers for the input.

One thing though, there are some areas of just bare wood with no Posca paint on, and the finish is tacky there too.

GoldenEraGuitars

Before you do anything, move the body somewhere with air flow. As mentioned above, you may think a warm enclosed area would be the best solution but this usually stops the finish from drying properly. If you’re using a water based system your finish will need time to dry, not cure. 

mikem8634

GoldenEraGuitars said:

Before you do anything, move the body somewhere with air flow. As mentioned above, you may think a warm enclosed area would be the best solution but this usually stops the finish from drying properly. If you’re using a water based system your finish will need time to dry, not cure. 

I will do. I don't intend to rush anything as I'm in no hurry. At the moment I've got them hanging in a room with open windows. Another option would be a draughty garage.

Good to know that I shouldn't worry about curing with water=based stuff. There is soooo much to learn.

Roughly how long should I give it in that kind of environment before accepting defeat?

GoldenEraGuitars

mikem8634 said:

GoldenEraGuitars said:

Before you do anything, move the body somewhere with air flow. As mentioned above, you may think a warm enclosed area would be the best solution but this usually stops the finish from drying properly. If you’re using a water based system your finish will need time to dry, not cure. 

I will do. I don't intend to rush anything as I'm in no hurry. At the moment I've got them hanging in a room with open windows. Another option would be a draughty garage.

Good to know that I shouldn't worry about curing with water=based stuff. There is soooo much to learn.

Roughly how long should I give it in that kind of environment before accepting defeat?

It’s really a case of trial and error with the manufacturers recommended methods. Although you also have to adapt your spraying method to the environment you’re in as well. 

Reading back on it, you've applied 10 coats? And one was particularly wet? I’d just leave it as long as possible and keep it somewhere that air can get to it. 

mikem8634

Many thanks @GoldenEraGuitars - sounds like a plan

mikem8634

Received this from Montana's R and D lab in Spain which confirms the excellent advice above

Hi

Thanks for writing us.

Water Based Varnish is an acrylic product, so it hasn’t cure times. If your work stays tacky after some days should be due the thick layers that has make a “shield” in the surface delaying the evaporation from deeper layers

It will be dry slowly. Depending on the thickness it will need more or less days, so you can wait. For future projects remember the rule: 2 thin layers are better than a thick layer.

Regards

GoldenEraGuitars

@mikem8634 this is the same with a lot of products.. the outer layer dries faster than the previous layer and traps vapor under the surface. Different products yield different results. 

mikem8634

@GoldenEraGuitars it's all starting to make some sense now. I'm feeling way more positive that the bodies will dry now, but if they don't it's been a great learning experience and I shouldn't make the same mistakes again.

No doubt I'll make a load of new ones.

I sprayed some headstocks black today and adapted the process to take into account the advice from you and @WezV.

And apologies to @axisus for the thread crash.

axisus

mikem8634 said:

And apologies to @axisus for the thread crash.

No worries at all, plenty of useful information!

mikem8634

Well, update on the water based varnish I've used. It still hasn't properly hardened. It's very slightly tacky to the touch and, whilst I can't make a fingerprint in it, it's really easy  to mark with a fingernail. Over a month now since I sprayed it. It's had ventilation, a fan, heat, a wipe over with white spirit, so I'm about to call it and sand it back with 600 or 800 grit.

One final suggestion I've seen is a light coat of shellac over the top. Any ideas if that's worth trying?

Kalimna

Im only on my 6th nitro finished guitar, but if its still 'soft' then id be surprised if adding another layer would improve the outcome. 
I suspect you're heading towards sanding right back

Adam

Jalapeno

I've used poly finish rattle cans, including topcoat but they never really cured hard - suffered the fingernail issue.

On advice from the poly supplier (and Steve @NortWest), I cut back to bare wood, repeated the poly coats, but used nitro top coats - that cured a lot tougher, not rock hard, but a lot more resilient

SteveRobinson

Jalapeno said:

I've used poly finish rattle cans, including topcoat but they never really cured hard - suffered the fingernail issue.

On advice from the poly supplier (and Steve @NortWest), I cut back to bare wood, repeated the poly coats, but used nitro top coats - that cured a lot tougher, not rock hard, but a lot more resilient

Did it craze? Usually if you put a hard finish on top of a soft one, the finish will craze very quickly

mikem8634

Pretty much how I see it too Adam @Kalimna, thanks.

And what you say there @Jalapeno just highlights the main problem with my inexperience - not only do I not know what to do, but I also don't know what to expect. Perhaps I'm expecting too much and this product has done exactly what it does.

I should also point out that I don't mind the finish being not the most protective, if the guitars pick up dings and scratches in their life I'm not at all bothered, but I'm not comfortable with the vague adhesive tackiness. Just feels a bit weird.

Jalapeno

SteveRobinson said:

Jalapeno said:

I've used poly finish rattle cans, including topcoat but they never really cured hard - suffered the fingernail issue.

On advice from the poly supplier (and Steve @NortWest), I cut back to bare wood, repeated the poly coats, but used nitro top coats - that cured a lot tougher, not rock hard, but a lot more resilient

Did it craze? Usually if you put a hard finish on top of a soft one, the finish will craze very quickly

Not yet, did it over a year ago.

@mikem8634 I used Montana cans for my colours, and NortWest Nitro for the finish - this is the result my Tomato Ketchup Burst PRS SE SC Korina.  My first attempt (well second it you count the strip-back and start again).