In your tutorial on spraying you state that you use Mirotone catalyzed lacquer and they supply both precatalyzed lacquer and acid catalyzed lacquer. Which one do you use and why. The reason I ask is that after having a good think today and going over Peters thread I think its time I give up on the water based thing. When I have used nitro I have used my mates booth so I will go back to bugging him but nitro has its problems up here as well so I want to go with your recommendation Allen. While I'm here thanks for the spray tutorial as well.
Jim
Spray question for Allen
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DarwinStrings
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I'm using Mirocat 3220 and Mirotone's thinner. I'd recommend getting some of their retarder as well. I never mix different companies products. Even if you think that they are the same thing, too many times there is an additive that is designed to work with the product it's intended for.
The reason that I'm using this one is that the only company in Cairns that sells it, only stocks the 3220. Mirotone also states that this one is desinged for finishing musical instruments besides other things. I've thought about trying the acid cat one, but it's a special order, and you know what that entails when you live up here.
Spraying in the tropics isn't that difficult. You're just going to be contending with humidity, that is going to cause blushing, and you can either choose the time you spray when conditions are favorable, or use up to 10% retarder. In fact, blushing is far more common when it's cold and damp out rather than hot and damp. It was a constant battle back in Canada with blushing when we were still using lacquer to spray automobiles.
The retarder keeps the surface of the paint film from skinning over too fast, and allows the moisture that gets mixed and trapped in the finish during spraying to escape. If you do get blushing, don't panic, it's an easy fix and nothing to worry about.
It's this trapped moisture that makes the surface look dull. If it's relatively light blushing, just letting the surface dry out for a week or so will sometimes bring the gloss back up, or just spray a couple more coats in more favorable conditions, preferably with some retarder added.
I find that if I cut the lacquer between 40 and 50% and add a splash of retarder, this mix works all year around for me. It's cutting more than Mirotone says is necessary, but it gives you far more control of the film thickness, is easier to spray, and dries faster. The fastest way to crazing of a finish is getting it on too thick.
I spray 5 coats with about 15-20 minutes flash between each. Let dry over night then give the surface a light sand back with 320 dry. This opens up the surface, allowing solvents to gas off faster. I use my nose to tell me if it's dry enough to go to the next spray session. When I can't smell solvent anymore, I give it a thorough sanding, then another 5 coats just as before. This time I just let it hang in a well ventilated place for a week or so before sanding and buffing. I almost never require a third spray session. If you've done your pore filling properly, you won't either.
The reason that I'm using this one is that the only company in Cairns that sells it, only stocks the 3220. Mirotone also states that this one is desinged for finishing musical instruments besides other things. I've thought about trying the acid cat one, but it's a special order, and you know what that entails when you live up here.
Spraying in the tropics isn't that difficult. You're just going to be contending with humidity, that is going to cause blushing, and you can either choose the time you spray when conditions are favorable, or use up to 10% retarder. In fact, blushing is far more common when it's cold and damp out rather than hot and damp. It was a constant battle back in Canada with blushing when we were still using lacquer to spray automobiles.
The retarder keeps the surface of the paint film from skinning over too fast, and allows the moisture that gets mixed and trapped in the finish during spraying to escape. If you do get blushing, don't panic, it's an easy fix and nothing to worry about.
It's this trapped moisture that makes the surface look dull. If it's relatively light blushing, just letting the surface dry out for a week or so will sometimes bring the gloss back up, or just spray a couple more coats in more favorable conditions, preferably with some retarder added.
I find that if I cut the lacquer between 40 and 50% and add a splash of retarder, this mix works all year around for me. It's cutting more than Mirotone says is necessary, but it gives you far more control of the film thickness, is easier to spray, and dries faster. The fastest way to crazing of a finish is getting it on too thick.
I spray 5 coats with about 15-20 minutes flash between each. Let dry over night then give the surface a light sand back with 320 dry. This opens up the surface, allowing solvents to gas off faster. I use my nose to tell me if it's dry enough to go to the next spray session. When I can't smell solvent anymore, I give it a thorough sanding, then another 5 coats just as before. This time I just let it hang in a well ventilated place for a week or so before sanding and buffing. I almost never require a third spray session. If you've done your pore filling properly, you won't either.
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DarwinStrings
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Ok many thanks Allen. So I'll be happy to go with the precatalyzed but you also mentioned that you were thinking of trying the Acid catalyzed and didn't because of the problems associated with being a turnip farmer. Why would you try the Acid if you are happy with the pre. It says things like longer pot life which seems not needed for the technique you use. The 3220 says "excellent surface hardness" which is what i feel is needed.
Jim
May the gophers never wreak havoc in your turnip patch
Jim
May the gophers never wreak havoc in your turnip patch
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Bob Connor
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I'm very happy with the 3220 but I wanted to give the Mirotone Polyurethane a try.
Dave Churchill has been using it and he was saying it doesn't "ball up" like the 3220 does but just sands off to a fine dust. I've been using a Festool ROS and the 3220 leaves swirl marks when it "balls up" (sounds like a balls up doesn't it.)
I think it can be sanded back in a few hours as well.
I believe it's also is harder than the 3220 when cured
Dave Churchill has been using it and he was saying it doesn't "ball up" like the 3220 does but just sands off to a fine dust. I've been using a Festool ROS and the 3220 leaves swirl marks when it "balls up" (sounds like a balls up doesn't it.)
I think it can be sanded back in a few hours as well.
I believe it's also is harder than the 3220 when cured
I've given up even trying to sand the 3220 with the Festool. It's just not worth the hassle of loading up paper that's just been put on.
My one concern with the Polyurethane is that it's going to need much more controlled conditions, like the spray booths we have at work, but as I said, I only get sporadic access to them. So I guess I'll be sticking to the 3220.
My one concern with the Polyurethane is that it's going to need much more controlled conditions, like the spray booths we have at work, but as I said, I only get sporadic access to them. So I guess I'll be sticking to the 3220.
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DarwinStrings
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Taffy Evans
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My last few guitars and a couple of mandolins were sprayed with Mirrotone NC3047 Clear Gloss Topcoat, I do not have any other information, It appeared to work ok used as per Allens suggestions. I'm just about to buy some more lacquer so I'll check out the 3220. Its funny I drove past the supplier today 130k away, but changed my mind about buying new stocks.
Taff
Mirotone's 3220 base is nitrocellulose lacquer. They've added plasticizers and other goodies to help it harden and have the desired flexibility so it doen'ts check so readily. If you apply it too thick, it will check though.
Spraying lacquer if pretty well a no-brainer. As long as some great big fly doesn't land in it as your spraying, there isn't a cyclone going on, and it's not getting wet, then you can spray it pretty much anywhere that isn't going to annoy the neighbors. Most of the time I spray out in the shed, and let the breeze take the overspray away. The overspray is dry within seconds, so it's nothing more than lacquer dust when it lands on something. It flashes off so quickly that dust and bugs really aren't a problem, and if by chance one does land in the wet film, then just wait 20 minutes or so, and lightly scuff them out. This is another reason to cut the lacquer about 50%. It's thin as, and very forgiving of quick repairs like this.
Once fully dry, it is very hard, but not bullet proof. I let one bloke try one of my guitars without a pick guard, and he used a pick like a scraper. Marked the finish up some. I had to sand back with 2000 grit and buff again.
With something like Polyurethane or Polyester, you will have to spray it in a spray booth, as the surface is going to stay open far too long. If you sprayed it outdoors, the overspray is going to still be wet when it lands on your neighbors black BMW, and he's going to be pissed at you. And you simply can't do a spot repair like you can with lacquer.
You also better be pretty good with a spray gun. As the product is going to have a lot more body to it, and runs are going to be much more difficult to deal with. It's best to think "What you see is what you get".
Another thing about lacquer finishes, is that they are really easy to do invisible drop fills on, when you get that occasional gap in purfling strips. Not so with Polyester. Polyester won't melt into itself, and you're going to get witness lines if you try this. Most times you may not notice them, but it's still something to consider.
Spraying lacquer if pretty well a no-brainer. As long as some great big fly doesn't land in it as your spraying, there isn't a cyclone going on, and it's not getting wet, then you can spray it pretty much anywhere that isn't going to annoy the neighbors. Most of the time I spray out in the shed, and let the breeze take the overspray away. The overspray is dry within seconds, so it's nothing more than lacquer dust when it lands on something. It flashes off so quickly that dust and bugs really aren't a problem, and if by chance one does land in the wet film, then just wait 20 minutes or so, and lightly scuff them out. This is another reason to cut the lacquer about 50%. It's thin as, and very forgiving of quick repairs like this.
Once fully dry, it is very hard, but not bullet proof. I let one bloke try one of my guitars without a pick guard, and he used a pick like a scraper. Marked the finish up some. I had to sand back with 2000 grit and buff again.
With something like Polyurethane or Polyester, you will have to spray it in a spray booth, as the surface is going to stay open far too long. If you sprayed it outdoors, the overspray is going to still be wet when it lands on your neighbors black BMW, and he's going to be pissed at you. And you simply can't do a spot repair like you can with lacquer.
You also better be pretty good with a spray gun. As the product is going to have a lot more body to it, and runs are going to be much more difficult to deal with. It's best to think "What you see is what you get".
Another thing about lacquer finishes, is that they are really easy to do invisible drop fills on, when you get that occasional gap in purfling strips. Not so with Polyester. Polyester won't melt into itself, and you're going to get witness lines if you try this. Most times you may not notice them, but it's still something to consider.
Last edited by Allen on Sat Jan 10, 2009 7:57 pm, edited 1 time in total.
It's been brought to my attention by a member of the forum, that some prominent Australian builders have had crazing problems with Mirotones 3220. I've not had any problems with the product, but have seen it happen to others using the product in a manner that I don't feel is appropriate. Ie. too heavy, thick a finish, too fast.
I feel that Mirotones instructions are targeted at the cabinet maker (by far their largest consumer) who is wanting to spray 1 or 2 coats on a piece, that will have the desired film build. The problem arrises when you try to apply their product to a guitar in the same manner, but apply 5 coats, rub back and another 5 coats. This is far too thick of a film build and you will surely get crazing. This is why I recommend that you thin the product by 50%. Less film build
I thought that this should be put out, so you all can make an informed decision. A product that was recommended was one by Durobond. I'll give their product a try once this batch of Mirotone is done.
I feel that Mirotones instructions are targeted at the cabinet maker (by far their largest consumer) who is wanting to spray 1 or 2 coats on a piece, that will have the desired film build. The problem arrises when you try to apply their product to a guitar in the same manner, but apply 5 coats, rub back and another 5 coats. This is far too thick of a film build and you will surely get crazing. This is why I recommend that you thin the product by 50%. Less film build
I thought that this should be put out, so you all can make an informed decision. A product that was recommended was one by Durobond. I'll give their product a try once this batch of Mirotone is done.
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DarwinStrings
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Bob Connor
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Last time I spoke to Pat Evans from Maton they were using Mirotone products, I don't know which one. I think it was 3220 because he was enquiring what we were using and said something like " that's what goes on most of our instruments". So don't quote me but I think this may be the case.
He said the only problem they had was that the Mirotone people had changed the formula a few times without telling anyone and this caused them a few problems. He didn't elaborate any further.
He said the only problem they had was that the Mirotone people had changed the formula a few times without telling anyone and this caused them a few problems. He didn't elaborate any further.
I just wanted to clarify about paint reduction, as perhaps everyone has a different interpretation of what 50% reduction is. As far as I know, all paint manufacturers base their reduction recomondations on how much of their product is in the ready to spray mix.
Therefore a 50% reduction means that there will be 1 part solvent to 1 part product.
Therefore a 50% reduction means that there will be 1 part solvent to 1 part product.
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