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[Solved] dissapointing finish

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*can anybody help* after applying grain filler.. then sand and seal and finally my top coat of Satin finish however the lacquer has turnerd milky ! is this correct or as i suspect not correct any tips what am i doing wrong !

9 Answers
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Alan, first of all, don’t panic, this is very common and fixable. 

The milky appearance is called “blooming”. It’s when moisture from the atmosphere gets trapped in the lacquer and has that milk look to it. It tends to happen when you spray too much lacquer at once. You have to be aware of the environmental conditions on the day you are spraying. If the relative humidity is high (eg. 60%, 70%, 80% etc) then that is not going to be a good day to spray your lacquer, you will experience blooming. When the lacquer is dry, just sand it all back until the bloom disappears and you can respray it again. Try to spray on dry days and ideally your environment should be kept as consistent as possible as the temperature and humidity changes through the night. Keep your lacquer coats light as you are spraying them and leave longer periods in between coats. If the coats are too wet or you try to build up the finish too quickly, you have more chance of getting bloom. Spraying paints and lacquers is a game of being patient, slowly does it, it’s not a race. 

Invest in an inexpensive humidity sensor and thermometer for your work environment to help you judge the conditions. 

When you watch professional paint sprayers online, such as JN Color who works in the Fender Custom Shop, you have to remember that they are working in climate controlled work environments. For the man in the shed, it’s not going to go as well. 

The type of paint you are using as well makes blooming more susceptible. I’m going to go out on a limb here and say you were using nitro in a rattle can? Always problematic in non perfect conditions or applied incorrectly, it’s not easy to use.

Your project isn’t ruined, you just need to sand off the lacquer you have sprayed on and reapply it in better conditions. You need a lot of patience, it’s just part of it. 

Good luck and I hope this helps. 👍 

Boo. 

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Alan, here is my humidity gauge and thermometer that I leave in my working area, it just helps me make decisions about spraying and other things such as gluing wood etc. Here in the UK it tends to be ok for spraying most of the year, apart from winter but I choose to spray about midday when the atmosphere has warmed and a lot of the moisture has gone. We do get some warm and wet days so the humidity will be high, I just don’t spray on those days. My sensor will tell me when it’s good to go. It needs to be about 45% to 55% to be good spraying conditions. Dryer can be good but not always. 

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Alan, can you upload some pictures so I can have a look? 👍

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@boo
Hi Boo
yes I will post some pics tomoz ,,, recieved my humidity guage + Fresh can of nitro lacquer today ... humidity reading 55%-67 % so your advice paid off straight away without the humidity gauge, I would have plodded on regardless "resprayed" and been back to square one I so mega thanks ,
will try different finishes on future builds more research required. espicially using this forum cheers

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Topic starter

Thanks Boo it was like someone kicking the ladder from under you the project had gone really well up until that point. 

following Marks online course so you are correct in assuming im am using nitro rattle can. first guitar so couldnt justify the expence of a 

proper spray gun but will maybe go down that route as i am hooked so i will be building more guitars 

I can relate to exactly to your comments defo prob to eager + laid on to thick.

 living in northwest we tend to get a lot of rainy weather ha ha ... humidity gauge now ordered 

after standing there looking in disbelief for a couple of hours i have started to lightly sand also ordered so more lacquer 

you tips were really helpful thanks for your support 

cheers Boo  

@alancoffey Yeah I live in the NW, near Blackpool so I know what you mean about it being wet a lot of the time. There are other finishing products you could use other than nitro that aren’t as temperamental. You could use acrylic lacquer or 2k clear, both available in rattle cans.

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Interesting comments about humidity. When I visited the Martin factory in 2013 they spray in 30 to 40 % humidity and 60 to 70 deg F which surprised me, however Nitro is highly explosive and that’s right on its “flash point” so hot and dry is not always good.

Some people call me a tool, others are less complimentary. Tools being useful things.

@rocknroller912 Yeah, that is crazy, very risky. I can’t stand nitro if I’m honest, people only use it on guitars because they think they should and that’s what all the guitar building supply shops sell. Paint products have moved on for the better. Thanks for the info. 👍

@boo
I agree with you about nitro and it’s hard to source in the UK anyway.. Oil finishes which dry without UV are available for brushing but are very expensive. I think we are all learning from the work that you are posting.

@rocknroller912 Thanks for that, I appreciate it. That’s why I continue to post a lot of pictures, even of any mistakes and/or repairs during the finishing process, I want everyone to get good finishes on their projects. A lot of it comes from experience but some from trial and error and I don’t mind getting it wrong sometimes. Using oils can be tricky but the more practice you have, the more you understand it and learn what to do and what not to do. I honestly must do some videos at some point to demonstrate oils and paints.

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@boo

I think I posted a link to a video of making oil varnish at home a while ago, not for the faint hearted and colours are limited as it’s the heating process which creates it. I’m not sure how well it would work over stains.

Some people call me a tool, others are less complimentary. Tools being useful things.

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Topic starter

Hi Boo as you can see the pic are not that great really would have been very helpfull if i had took them before sanding.

the humidity is pretty dam horrible my workshop is a decent sized  wood logde and the humidity is pretty much the same most of the time,

looks like I may need to invest in a humidifier

unfortunately i had already started to sand out the lacquer before taking the pics  the back to befair came out resonably well,

however the top took a bit of a beating I thinking it might be best to sand more and lay on a couple of coats of sand + seal 

and bite the bullit 

sanded with 400 grit then went to 1000 wet dry then 2000 wet dry this put a really nest sheen on the parts of the guitar that 

hadnt been sanded through ,, hope that makes sense 

Alan 

 

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Right, before you spray anything else on, whether it’s sealer or lacquer, sand the whole thing with some 600g paper. Don’t spray anything over 2000g it’s too shiny, nothing will stick to it properly. There has to be enough “key” to the surface so the new paint/sealer/lacquer has something to hold on to. What would happen is over time the lacquer will start to bubble, lift and crack, resulting in it falling off (not when it’s wet as you spray it but when it dries, it could take weeks or months to start showing). 

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@boo thanks Boo I will resand with the whole guitar with 600g , good sound advice.
then respray when the humidity is right.
your advice is really appreciated saved the day cheers

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Alan, have you looked at the Finishing Course that Mark made on here? 

I highly recommend it to you. 

https://guitarmaking.co.uk/course/guitar-finishing/  

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