NC vs Acrylic Lacquer

SilentC,
There is an old saying "first read the instructions" sorry but it would have helped you here.

First thing turn UP the air at the gun So the gun sprays properly if its too low the lacquer can't be put on wet enough to give a smooth (unpatchy) finish.

Then turn IN the material so that when you spray normally you get a wet smooth coat. ( usually around half way on the control depending on the gun.)

If the timber you have is open grained it will be real hard to fill the grain with lacquer. Air comes out of the gun first, it hits the timber goes into the holes and blows back out when the paint arrives the paint can't get into the grain easily, result the grain cells have trouble filling. Some does go in but you put more on the high spots than in the holes, so you need to put on a lot of coats and then rubthem to remove the excess. The gun puts on an even coat so if you put on enough to fill the grain you will also put just as much on the area around the grain hole.

If you use sanding sealer first it is designed to work better it seals and fills, you then sand it so you reduce the build up on the surrounding areas giving the lacquer a better chance at filling. Wood filler is used to fill the grain on soft timber to give you a flat surface which makes clearing easier but it can alter the colour of some timbers so much people try to avoid it and fill with the clear. It will always be easier to cover a flat blemish free surface than a pocky one.

Next - one coat at a time if you can afford to leave it 20minutes or longer between coats more if the tempo is below 20 C. If you put on five coats over 24 hours it will be far drier than 5 coats in 10 minutes after both are left for a week to dry.

The bubbles are caused by the solvent trapped underneath, trying to get out. The top coat dries first as its closest to the air (the thinners is evaporating off) the ones underneath have no choise but to drive up through the top coats. ( they form bubbles) It's called solvent boil. So let each coat dry off most of the solvent before you hit it again.

Don't put the timber near heat ( especially infra red lamps) as this will increase the chance of the bubbles, have it somewhere where the air is warm only with no intense heat pointing at it. Those convection heaters which blow hot air work best, Just warm up the area with one. Whatever you do don't put it in mum's oven or a sealed up area that the solvent coming off can't escape from.

Sunlight is good especially at this time of the year but not in the summer. Too much heat on wet paint on timber also causes bubbles when the air trapped in the timber grain is forced out by the heat.

What you experienced has always happened with timber, the old way to solve the problem was french polishing, it can also be done with lacquers. instead of putting on piles of coats a few coapts were applied and then the polisher used a solvent laden pad to remelt the material rubbing it into the grain and smoothing out the surface. Now its put on excess and rub off most to level the coating.

Waste of time spraying thinners on it, can't think of one good reason to need do that all you will do is slow the drying down further

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first read the instructions

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The instructions on the tin? I should take a picture, it will make you laugh. It's the same label they put on all of their products, with about four lines for each. You just have to guess which ones apply to you.

OK, I'll have another play. As I say, it was only a test panel. Just wanted to see what it would look like. It's water-clear and doesn't colour the timber at all. Having said that, I think the shellac gives the timber a nice golden glow which seems to suit the brownish tones of the Banksia, so I'll probably stick with that for this project.

Thanks for all the tips. I'll practice it until I get it right before I try it on anything that counts though.

So if I wanted to get a low sheen finish with the high gloss stuff, can it be done?

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Originally Posted by durwood

Do you know what to expect with candy colours?

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Not really, have only read a little about them. From what I gather they consist of either a black or silver base, then coated with the candy to what ever depth of colour and then finished with several coats of clear? All of these coats are wet on wet?

Do you have any candy application tips?

Matrix,

If the candy's are acrylic then you can not put them on wet on wet. WOW is a quick way of applying 2 pack paints on things that don't matter not the prefered way.

Depending on what the final colour you are after will depend on what colours you use. Black as a base would be pretty useless.

The candy colours are dyes suspended in clear and cover terribly. Put on black they would not show up real well unless out in strong sunlight.

Usually the base colours are light bright colours, silver or gold sometimes white but usually a metallic colour. Normally the colour is picked from a card and the base and candy combination give you the result. There is nothing to stop you making up your own versions but if you are experimenting I would stick to a known colour.

After primer and rubbing you apply the base, keep the number of coats to a minimum, try for 2 maybe 3 all you need is coverage of the primer. let it dry for at least 1/2 hour and remove any faults and redo the base if necessary.

Mix the candy colour thin and the gun you use must be a good one which will spray a nice even coat. Don't waste your time if it doesn't.

The problem with candy is the colour is bright and see through, if you put it on unevenly it will look terrible. So you must always spray even coats if you try to overlap as you would with a solid colour it will just go streeky. once its unever its impossible to get right. Large surfaces are a real challenge.

Hold the gun further away than normal make sure the fan is open and mist on light coats over the surface. Use a criss cross method so that there is no detectible pattern to your spraying. If the paint is really thin it will fall on the surface as fine particles if its sandy thin the paint more or turn down the air. Its always possible to add more but not to take it off so take it easy till you get your candy how you like it.

If you look at the post two back to SilentC first it will also help. Don't rush the application let the material dry.

Once the light candy coats are on spray one coat of clear over the candy and let it dry. While its drying if anything gets on the surface you will be able to wipe it off the clear, you will disturb the candy pattern if you try to wipe something off it.

You can not rub or touch the finish so make sure you have everything clean. If any dirt falls on the job you will have it forever. AS its so transparent you can't block it out with the candy. If you try to rub faults out you will make a bald spot.

Let the clear coat dry for as long as possible 1 hour or more, and then add 2 -3 more leaving each to dry out. Then leave it about a week before you compound or polish.

You can flatten the clear to remove any peel before buffing but take it easy.

You might have noticed you rarely see candy colours, especially on large jobs. Its been used widely on bike tanks etc but not so much on cars and other things. The dyes are not real good in sunlight and fade quickly so its usually show hot rods and other things not left out in the weather that work best.

If you over do the number of coats and don't let them dry out properly the whole job ends up cracking badly. Expensive little exercise after all that expensive material, time and effort. Metal flake fares even worse.

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So if I wanted to get a low sheen finish with the high gloss stuff, can it be done?

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Ahem..

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Originally Posted by durwood

What you experienced has always happened with timber, the old way to solve the problem was french polishing, it can also be done with lacquers. instead of putting on piles of coats a few coapts were applied and then the polisher used a solvent laden pad to remelt the material rubbing it into the grain and smoothing out the surface. Now its put on excess and rub off most to level the coating.

Waste of time spraying thinners on it, can't think of one good reason to need do that all you will do is slow the drying down further

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I wasn't going to respond, because there's nothing worse than someone who doesn't know too much giving wrong advice, so please take this with a grain of salt:

Isn't the answer to the second paragraph, answered in the one before? Instead of using a pad, a fine mist of solvent will allow the surface to find it's own level. It may not be the sort of thing a tradesperson would do, but it works on occasion for this bumbling amateur! :wink:

Cheers,

P

dont'cha love ameteurs,
coz they don't know it cannot be done
some of 'em do it and make it work

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Originally Posted by durwood

silentC,
Nitrocellulose lacquer is a very inferior product compared to acrylic lacquer.

Its main problem is its bad performance if subject to sunlight. The resin goes brown and cracks making the whole finish breakdown in less than 6 months in our climate.

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First off all it simply doesn't brown at all.....it ambers.

It doesn't crack......it "checks"........checking is mostly caused by rapid humidity change and wood movement. They aren't like cracks in poly that go all the way through.........think of it akin to blistered skin.


http://www.fretnotguitarrepair.com/images/DCP_3847.JPG

The below link is an example of a "crack"

http://s659.photobucket.com/albums/u...z/crazing5.jpg
http://s659.photobucket.com/albums/u...g5.jpg%3C/a%3E


One is terminal, the other is not...

Nitro does not completely break down within six months in our climate....that is such an epic exaggeration.

I doubt if at your age you would have had or seen much in the way of N/C lacquer or what happens to it over a period of time..but I have, over 60 years experience with it. It was all that was available when I was an apprentice (N/C lacquer and enamel) Humidity and wood movement has nothing to do with it checking or cracking as the same material would react the same if it was on a more stable surface such as metal. I don't know if the photo you posted is something you have but if it is try looking at it through a microscope, bet its cracked right the way through to the wood or sanding sealer. A painter would strip it off completely as invarably the cracks are right through the finish. The only sure way to get a successful repair is to get rid of all the coating. It may be the N/C has split because the sanding sealer has failed.

N/C lacquer was developed after World War 1 and was one of only a couple of finishes available for 50 years. It is probably the easiest and most forgiving paint to use on any but there are far better finishes to use especially if what you are coating is valuable or you have spent hours making You need a good reason to use it instead of other products and there isn't many.

GMH up until acrylic lacquer was marketed in the early 1960. When they swapped to Acrylic lacquer. A/L was so superior that Holdens were advertised as having "a majic mirror finish" not needing to be polished for 12 months or more and not fading for 10 years N/C colours faded in less than 12 months. If you had a white Hoilden it would be cream shortly after you bought it. .

Checking is one of the steps in the breakdown of a finish. depending on the severity of the breakdown of conditions ( thickness of coating - application method-surface coated)

Crazing- fine hair line lines such as one gets in china
checking - where the lines go in lines more than criss crossing as in your photo
crows feet - where the cracks split out radially but don't necessary join ( looks like a birds foot print.)
Cracking- where the surface splits wide open when the paint shrinks and pulls apart.
Eventually the N/C will crack, shrink,and peel off given the right conditions.

N/C will go amber then brown actually it will go black and disintergrate completely eventually if you leave it long enough. Ask someone who was around cars in the 1970's and see if they remember sports cars with soft tops. The cellulose windows would go amber, brown, black and eventually crumble leaving you with no window at all. You can even see it happen with cellulose tape when its exposed to strong light.

N/C only exists to be used for finishes that are normally not exposed to harsh conditions such as a piece of furnature or a guitar etc One would need to be carefull what you used it on or the effort and expence would be sort lived. There are enough of us who like it that it still pays some manufacturers to produce it. But as a finish its not that great compared to others now available.


In the 1970 every paint company in Australia supplied N/C lacquer now it can be neally impossible to find in ones area.

Put it on something exposed to sunlight such as a car (even on the wooden dash) and it will only last weeks.

Acrylic helped solve the N/C problems so much GMH was able to offer metallic colours which contain mainly clear for the first time. They wouldn't have made it through warranty if they were on a Holden when they used N/C. All other cars were finished in baked enamel which GMH eventually changed to also but the only paint available to use to repair them was N/C which resulted in cars being covered in different coloured spots where they were touched up. Acrylic solved this problem so everyone could have a car which was the one colour.

If a paint checks cracks or does anything similar it probably means that the person applying it has got it wrong, usually applying too much material or added to a surface already with maximum thickness on it. One of paint strippers main use is to remove excess paint so new paint won't crack/check etc.

The clear discolouring is a result of the UV light, N/C is not unique in this regard. Interior finishes such as Estapol also do it. Exterior clear finishes which don't yellow have inhibitors in them which add to the cost.

You are right it doesn't break down in 6 months - if you keep it insde out of direct sunlight. last even longer in a dark room but if you put all the available clears on test panels in a window in sunlight shellac would be the only finish to collapse before N/C.

If anything is going to breakdown our climate is the one for it to happen in, we have possibly the worse conditions for paint finishes. North Queensland and Florida in the USA are the top places for testing the quality of finishes.

Such a shame Kiama is so far away. It would be awsome to spend a few hours learning the finer points of spraying:(

Your assumptions are based on extreme hyperbole.

Yes.....nitro came after the first great war......they needed something to do with all that armanent nitrate.

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given the right conditions.

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Any finish will have problems given the right conditions.

Yes nitro yellows,
Yes nitro checks,
Yes nitro isn't a good choice for an automotive finish, that's why black and green were popular finishes. That's why you got pink cadilliacs that were originally white.

That's why you got an amazing butterscotch blonde telecaster that is now worth more than a years wage.

Your argument was dependant upon N/C's suitability as AN AUTOMOTIVE FINISH. That involves exposure to the elements.....more than just sunlight.....we are talking about rain, wind, extreme exposure to humidity. Yes acrylic lacquers are superior for those applications.


The reasons why N/C went out of favour are multiple....

There are a variety of issues

- It yellows.
- It checks
- It's highly explosive and is banned in many places because it is so explosive, and it's not very environmentally friendly.

But does it automatically degrade, as you suggested? No.......it needs factors to degrade.

Part of the stigma of N/C is the human error of using the finish for the wrong applications. It was used as an automotive finish simply because it was economical.It's like applying shellac as a bar top finish and then complaining about it dissolving from drunken spills.

N/C should of never been used as an automotive finish PERIOD.

Charlie watts has been playing a nitro finished drumset that was produced in 57-9. So that's 50+ years......of ROLLING STONES GRADE ABUSE........countless stages, outdoor, sweat, alcohol, grime, direct sunlight, you name it........as far as I'm concerned that's far more environmental abuse than your suggested 6 months.

[ame="http://www.youtube.com/watch?v=7PZug4854sI&feature=related"]YouTube - Charlies Drums[/ame]

Here is a 1928 Leedy Bass Drum............finished in DUCO black & blue...........The original nitro colours.....I'd say for 81 year old finish......it's in a pretty good state..........you can see the checking and wear and tear....but it's not terminal

http://www.thisolddrum.com/thisolddr...ueducobass.jpg

Nitro lacquer has it's place......If it didn't......no one would use it.

It looks great.....IMO there's nothing that gives the same effect, it's very repairable, it looks deep, it's applied faster than acrylics. Like any finish........it has it's drawbacks and they are many.

It's this inferior/superior mentality that has made polys virtually the only product on the shelf at most stores.

True I did use automotive as an example as that and marine are the extremes of paint use. If you want the best result for something you want to finish use them.

You missed the point, clear N/C is the unstable one, the UV light destroys it quickly the colours fare better. The original comments were in reply to a question about applying N/C clear on timber. If the question were about painting something else in a N/C colour then the answer is - it would be ok but better if it was done in acrylic.

If you want the best black for a top class finish then N/C black wins hands down. Thats why it was used on piano's ( they have since gone to poly because they can get the same result and have a more duralble finish) N/C it made it possible to get a first rate finish easily and it is very easy to repair. You can paint a small section in the middle of a large area and get an invisible result something hard if not impossible in most other finishes.

If someone wanted to paint something in N/C because ir is so easy to use then I would advise that he do so if thats what he wanted to do. Only trouble is you would be hard pressed finding supplies. You can get it in the USA but not of good quality here. The only N/C colour available here is poor industrial quality, used to coat things not expected to last long ( say a wheel barrow which is going to get the paint ripped off first load) but most manufactures go further and use better material such as powder coat or fast dry enamel as N/c needs buffing to get final gloss where the others dry glossy.

N/C wasn't used because it was economical. it was used because it dried fast, which cut down the problem of contamination from the air. It could be easily rubbed,buffed or touched up quickly. enamels on the other hand can't be buffed satisfactorly or touched up and they dry slowly making dust etc a real problem. When released in 1924 you could get your car painted in a day instead of weeks or months which it took before

By the way it is not highly explosive or banned because it is so, it does come from the same family as nitro glycerine but it was afailure as an explosive thats why the resulting glug was picked up as a paint . A lot of painters would argue that it was a lot safer working with N/C than the modern materials which require fresh air fed masks to protect them.

It was replaced with Acrylic (which has more volitile solvents) because it was inferior to A/L. No company is going to promote a product which can't compete with a competitors, same reason you can't get the old varnish now its just not up to scratch. All lacquers are being banned because of the massive solvent content they need to apply them (150% against 10%). Paint products are constantly being improved if any one of the vow available ones get piped by a competitors product the other manufacturer will quickly dump the old and replace it with a competitive one.

Poly is replacing them because its superior.It uses less solvent and is a lot better product, used with a hardener it dries rock hard in minutes amd doesn't need further work. lacquers require overnight drying and then polishing to achieve the same results. Lacquers also can be redisolved with solvent polys can be neally impossible to melt with paint stripper if need be.

A good clear poly can last 20 plus years against acrylic lacquers 10 years and N/C months under identical conditions.

N/C had a place it was good, I love using it but I would be hard pressed to pick it against other newer materials on something I had produced and wanted to last a long time there are better easier obtainable finishes. They may not be as fast drying though though if I had access to a heated booth they would be faster and they would certainly protect better stay in top order for a lot longer.

You know it seems to me that this debate centres around the emotional associations with finished objects from the past. It reminds me a bit of nostalgia for the crackle and pop of an LP versus the clean sound of a CD.

I guess the point is that only N/C will give an N/C finish, if that's what you are after. The fact that the items that are sought after have been finished with N/C makes the yellowed N/C look desirable, and so the wheel turns. They even have names for it eg. "butterscotch blonde", which seems to me is a whimsical way of saying "previously white but the lacquer has since turned brown".

If you are coming at it purely from the point of view of a durable clear finish, then N/C is probably not the way to go. On the other hand if you want to achieve the mellow, slightly crazed appearance of an old lacquer finish, then use N/C.

I could finish my cabinets with poly, it would be really easy to do so and I know it would outlast what I do use. However, I like the warm look of shellac, so that's what I use, even though I know it's not the most durable finish around.

I think 44Ronin is coming at it from the point of view of an early instrument enthusiast and remarks that deride the finish that identifies so many of those instruments obviously raise his hackles. He obviously feels strongly enough about the issue to dig out a two year old thread and object.

It's like that cartoon I saw once: "Are you coming to bed?" (guy frantically banging away at his keyboard) "not yet, someone is wrong on the internet!!".

Peace :)

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If you want the best black for a top class finish then N/C black wins hands down. Thats why it was used on piano's ( they have since gone to poly because they can get the same result and have a more duralble finish)

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Many prominent makers still stick with N/C.....Steinway & Sons still shoots N/C and hand polishes it

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It could be easily rubbed,buffed or touched up quickly. enamels on the other hand can't be buffed satisfactorly or touched up and they dry slowly making dust etc a real problem. When released in 1924 you could get your car painted in a day instead of weeks or months which it took before

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This is exactly why it is economical.....it makes for more efficient mass production..less labour and capital required.


Yes you argument is correct in general,

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Originally Posted by silentC

You know it seems to me that this debate centres around the emotional associations with finished objects from the past. It reminds me a bit of nostalgia for the crackle and pop of an LP versus the clean sound of a CD.

I guess the point is that only N/C will give an N/C finish, if that's what you are after. The fact that the items that are sought after have been finished with N/C makes the yellowed N/C look desirable, and so the wheel turns. They even have names for it eg. "butterscotch blonde", which seems to me is a whimsical way of saying "previously white but the lacquer has since turned brown".

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Spot on (except it yellows). That is exactly where I am coming from.

N/C ages....this aging does not have to be a negative characteristic.

In fact, to me it is a desirable and charming characteristic


From that...

https://www.petesrareguitars.com/pro..._02__66523.jpg

To this....

http://www.vintage-guitars.se/1960_F...189_tuners.jpg