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donslow

Painting issue help

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Can anyone explain why this is happening?!
 

The paint is dry but it’s dried with a matte finish (particularly the headstock) in places and glossy black (as it should) in others
 

confused :-s 

 

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2 hours ago, Geek99 said:

Paging @Andyjr1515

I'm not a spray man, I'm afraid.

There will be someone who knows what they are talking about passing by soon, I have no doubt :)

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But you know everything ... :)

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This looks like blooming/blushing to me. 


When the solvent evaporates and the paint dries, heat is extracted from the surface and the paint, drying it quickly. If any moisture is present this will condensate causing blooming. 
 

It’s possible to correct it with a clear varnish however it is better to avoid it in the first place by not painting where humidity is present. 

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Not sure if this helps but,     Next to my joinery shop there was a spray shop , and I’ve seen that happen to some of the finishes in there, it was caused by a drop in temperature while drying, not sure if that happened to yours, but it should be warm and constant while drying, they had to re sand it using fine contour pads and re spray 🙂

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Posted (edited)

I leave the cans in a bucket of warm water first - I’ve sprayed outside without issues 

Edited by Geek99

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7 hours ago, Dirty Soul said:

This looks like blooming/blushing to me. 


When the solvent evaporates and the paint dries, heat is extracted from the surface and the paint, drying it quickly. If any moisture is present this will condensate causing blooming. 
 

It’s possible to correct it with a clear varnish however it is better to avoid it in the first place by not painting where humidity is present. 

Makes sense but would that happen on just some parts of the neck?!

 

do you think going over it with clear Gloss nitro would rectify it somewhat?!

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Posted (edited)
1 hour ago, Geek99 said:

I leave the cans in a bucket of warm water first - I’ve sprayed outside without issues 

This could be a good shout, 

 

 

Edited by donslow

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1 hour ago, Reggaebass said:

Not sure if this helps but,     Next to my joinery shop there was a spray shop , and I’ve seen that happen to some of the finishes in there, it was caused by a drop in temperature while drying, not sure if that happened to yours, but it should be warm and constant while drying, they had to re sand it using fine contour pads and re spray 🙂


for what hits worth, I’m painting in the cellar under my house, it’s pretty dry and normally colder than anywhere else but it does have all the plumbing / drainage pipes running through it (could be moisture source)

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6 minutes ago, donslow said:


for what hits worth, I’m painting in the cellar under my house, it’s pretty dry and normally colder than anywhere else but it does have all the plumbing / drainage pipes running through it (could be moisture source)

I think you’re right, if it’s a bit cold or there’s moisture present it will get what looks like almost white patches on the surface, it can be nibbed back and re sprayed, maybe put a heater down there while you’re working 🙂

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5 minutes ago, Reggaebass said:

I think you’re right, if it’s a bit cold or there’s moisture present it will get what looks like almost white patches on the surface, it can be nibbed back and re sprayed, maybe put a heater down there while you’re working 🙂

Will give that a go today, may even drag it outside in the sun this afternoon

 

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I'll do a separate post about cellars and moisture - yes they can be a problem.

There cellars and there are cellars, but a general warning to anyone reading this who may not be aware (I am assuming, @donslow you are fully aware and therefore have all of the necessary precautions in place ;) ),  spraying anything - but especially nitro - in a confined space can be exceptionally dangerous.  We are talking fatality risk dangerous.   The precautions include, as an absolute minimum, appropriate and effective extraction facilities and the use of a purpose-designed and properly fitted respirator. 

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And so to cellars and moisture rather than cellars and oblivion :)

If it is a moisture problem (and I'll leave that to the spray gurus), then yes - the cellar might be an issue (and I can maybe add something here because my workbench is in our fairly small cellar).

Not all cellars are the same, but ours has a relative humidity issue in the warmer weather.  When it is cold outside, it is bone dry.  But when it warms up outside in the late Spring, in the corners and smaller spaces it is (literally) dripping wet.  Basically, the warm wet air from outside hits the cool walls and floor of the cellar and condenses out.  The air becomes super saturated and water droplets start forming on the surfaces and cold objects.  

More ventilation doesn't really help (although is essential if you are spraying, see above)), because it just brings in more moist air from outside.  So the irony - and I'm just about to switch it on - is that we have a thermostat-controlled oil/convector heater on ALL SUMMER!  We switch it off again in the autumn.  Which is bizarre, I know. 

Now yours may be different, but yes, moisture might be an issue in a cellar.

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I think your right!

I sprayed a guitar body in the cellar 6 weeks ago, and although the finish is as good as it will get, the paint STILL hasn’t dried or gone hard, still unsure whether that’s because it’s cheap paint (the paint on the neck from this post dried and went rock solid in a couple of days) or the conditions aren’t ideal, I’m still not sure but I’m thinking 6 weeks can’t be Right in anyone’s book?!

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Posted (edited)

now what to do with my home made “spray booth”

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Edited by donslow
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1 minute ago, donslow said:

And I was so proud of my home made, cellar bound spray booth ha ha ah well, at least I have somewhere to put the bodies now....

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Top job 👍

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39 minutes ago, Reggaebass said:

Top job 👍

Ha ha thankyou but it doesn’t work because it’s in the finish-ruining-cellar ha ha

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Posted (edited)
1 hour ago, Andyjr1515 said:

Excellent job!

...and that IS what I call a cellar!  Mine is around 8'x4' xD

It’s a massive space, we’re in a bungalow on a hill, the cellar is the size of the house, takes up the distance between hill and house, but it’s only about 6 foot high with steel girders hanging down with very strategic “crack your head on this“ placement, never stop doing it and it hurts like a bugger every time! The fact I’m bald means you always see every lump and cut when it does happen ha ha

Edited by donslow
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Only just seen this and was going to instantly say blooming but others have already enlightened you. I was also going say if the pain's not totally cured then try putting in the sun and it sometimes rectifies itself, which you've also found out. 

It occurs from moisture in the air condensing on your fresh paint. Warming the object you're painting can help, as can warming the paint but ultimately you need a dry drying area. 

I've sprayed outside when it's too cold and brought it back indoors between coats, and to dry, but you could see bloom developing when indoors in the warm and dissappear once back out in the cold. As @Andyjr1515 points to, it's all about moisture content of the air and it condensing with changes in temperature.

Warming the object to be painted and warming the paint is a good idea, it will still bloom if the moisture content of the air is too high but it will help, it also aids the application of the paint, giving a more even spray pattern from an aerosol and helping it flow better so you don't get the 'orange peel' effect in your finish. 

🙂

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Thanks @Maude, some very useful info to chew over!

one question if I may?!

ive since moved the neck outside in the sun, sanded and repainted and the finish is as it should be, would you know, if I left it in the sun to dry with the blooming, if I spray clear lacquer on top, would the “shade” still be that of the blooming or would it disappear so to speak?!

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10 minutes ago, donslow said:

Thanks @Maude, some very useful info to chew over!

one question if I may?!

ive since moved the neck outside in the sun, sanded and repainted and the finish is as it should be, would you know, if I left it in the sun to dry with the blooming, if I spray clear lacquer on top, would the “shade” still be that of the blooming or would it disappear so to speak?!

In all honesty I don't know as I've never tried. The blooming is on the surface but I think would still be visable if lacquered over as it's more of a whitening of the surface rather than a matting, which would become glossy if lacquered over. It's irrelevant though as if you let the paint with the bloom dry and then wanted to lacquer over it, you'd need to key the surface for lacquer so would just sand with something like 1500 wet until the bloom has gone, you shouldn't rub through as it'll only be on the surface layer. 

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