How can you fix a botched finish?

**the_dude** · Jun-28-2012, 6:08pm

I sprayed unevenly when I was applying my sealer and now there are uneven areas and drip marks. I thought I could try to sand the areas down, so I grabbed some 600 and started to sand the areas and drip marks. However, when I did this, bubbles were exposed underneath, which trapped the dust in them. How on earth can I remedy this situation?

**sunburst** · Jun-28-2012, 7:20pm

What is your sealer and what is your finish? Are you still sanding the sealer or have you already started applying finish and are you sanding that?

**RN Quits** · Jun-28-2012, 7:49pm

<abstruse post removed by Moderator>

**RN Quits** · Jun-28-2012, 7:51pm

**RN Quits** · Jun-28-2012, 7:55pm

**RN Quits** · Jun-28-2012, 7:56pm

**Marty Jacobson** · Jun-28-2012, 7:57pm

Are you using lacquer? If you are, then the dust trapped in the fisheye bubbles isn't really a problem. Blow the trapped dust out as well as you can with your air compressor (not a bad idea to have a little air filter on the end of your hose to keep any oil or moisture from hitting your instrument). Lacquer will "burn in" the dust and it will no longer be white or opaque.
If it's polyurethane or waterbased "lacquer" (I hope not), then you will have to be more thorough and sand down beneath the blemishes. Re-stain if you stained the wood, probably. Then try spraying again. Thinner coats with proper viscosity finish this time. It's more reps but it's less painful in the end.

(By the way, is anyone else very confused by the above messages? Does it look like a computer-generated response to anyone else?)

**RN Quits** · Jun-28-2012, 7:59pm

**the_dude** · Jun-28-2012, 8:15pm

Originally Posted by ArtDecoMandos

Are you using lacquer? If you are, then the dust trapped in the fisheye bubbles isn't really a problem. Blow the trapped dust out as well as you can with your air compressor (not a bad idea to have a little air filter on the end of your hose to keep any oil or moisture from hitting your instrument). Lacquer will "burn in" the dust and it will no longer be white or opaque.
If it's polyurethane or waterbased "lacquer" (I hope not), then you will have to be more thorough and sand down beneath the blemishes. Re-stain if you stained the wood, probably. Then try spraying again. Thinner coats with proper viscosity finish this time. It's more reps but it's less painful in the end.

(By the way, is anyone else very confused by the above messages? Does it look like a computer-generated response to anyone else?)

Very weird spamming going on here.

I'm using a nitrocellulose laquer as my sealer, so I think I'm safe.

How should I take care of the drip marks? Is the 600 grit I am using too fine or coarse?

Thanks a lot!

**bfleenor** · Jun-28-2012, 9:29pm

You can shave (or scrape) drip marks down with a disposable razor blade. Just be sure to put some tape on the corners or gently bend the corners up with your thumbs so they don't dig into the finish.

**Marty Jacobson** · Jun-28-2012, 11:32pm

Originally Posted by bfleenor

You can shave (or scrape) drip marks down with a disposable razor blade. ...

Yep, or you can use 320 or 400 grit sandpaper to get rid of the drips. If you are spraying lacquer without laying it on too thickly, you shouldn't be getting drips. Are you using a rattle can? If you're using compressed air and a decent spray gun, try playing with your fan width and air pressure if you are still getting drips. And just get the finish glass-smooth without building it up too thick. It takes some practice to get it to work without the overspray leaving gritting splashes on the rest of your work.
An HVLP rig is nice too, and not too expensive these days.

**the_dude** · Jun-29-2012, 7:10am

Originally Posted by ArtDecoMandos

Yep, or you can use 320 or 400 grit sandpaper to get rid of the drips. If you are spraying lacquer without laying it on too thickly, you shouldn't be getting drips. Are you using a rattle can? If you're using compressed air and a decent spray gun, try playing with your fan width and air pressure if you are still getting drips. And just get the finish glass-smooth without building it up too thick. It takes some practice to get it to work without the overspray leaving gritting splashes on the rest of your work.
An HVLP rig is nice too, and not too expensive these days.

This is my first build, and due to the inexperience and budget, I'm using rattle cans for the whole finish job. The drips were from my first couple of coats when I was just getting use to the spray.

Right now I have 3 coats of sealer on and still have a satin finish to put on. Do you recommend I sand with 400 grit, put another coat of sealer, and then finish?

**Wilbur Tabacsko** · Jun-29-2012, 11:48am

I've done seven mandolins with rattle cans. (about 25 cans, no wonder why I am poor) And I can say I've learned a lot about rattle cans. Since you are in the first stages of finish, I'd sand the entire mando with 320 or even 220 grit, paying attention to the "drips". If you feel you've sanded too much off, go ahead and spray another coat of sealer. When I spray my mandos I hold the mando in my hand, spraying certain areas one at time; top, back, sides, headstock,and neck. Doing this I can keep the surface level, avoiding runs. I wait til the surface of that area is dry then move onto another. It might take a half hour but it is worth the time. BTW, you should spray sealer coats lightly, not so much as to cause runs. I usually sand lightly after my seal coats then use my satin or gloss.

**Marty Jacobson** · Jun-29-2012, 3:32pm

As Wilburlin points out, you definitely can get a decent finish with rattle cans.

It isn't as easy as using a decent conventional gun, though. One thing to bear in mind is that the pressure is always being reduced, so when you're halfway through the can, the spray isn't nearly as nicely atomized as it was when it was full. So you have to pay attention and shoot for as light a coat as possible.

Post pictures when you get it looking great.