What's the go? My local paint shop can get acrylic lacquers from his supplier but not NC. I've read a little bit about it and acrylic seems to be the go if you want a water-clear finish. But other people on here seem to be into nitro-cellulose.
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What's the go? My local paint shop can get acrylic lacquers from his supplier but not NC. I've read a little bit about it and acrylic seems to be the go if you want a water-clear finish. But other people on here seem to be into nitro-cellulose.
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. Think sticky tape.
Its been used for interior use for a long time after the introduction of acrylic lacquer (1960) as it had been used since the 1920's and a lot of people were used to it. Don't get me wrong it is better than A/L in a lot of ways. It dries a lot faster ( rock hard in about 24 hours) where A/L takes at least a month to get to the same state. that makes it extremely easy to use especially if you mess it up ( get a run etc). The solvent used to thin it is not as strong as A/L also and it is less prone to act up.
Acrylic lacquer can be a real pain to work with compared to N/C the strong thinners attacks the finish and any problems can blow up into major catastrophies. You have to use very fine paper to rub it back as the thinner attacks the scratches. N/C is so easy to use you can spray straight thinner on it after scratching it with coarse paper and it will just melt the scratches into a glossy finish.
With the advent of polyurethanes, precat lacquers etc it is not being asked for as much and is therefore less likely the manufactures are prepared to keep producing the stuff.
All lacquers produce a lot of pollution due to the amount of solvent they give off because they have to be thinned down so much. Overseas they have been banned. Even A/L is banned you must now use a far better material. Even though 2 packs have a problem because the hardener is so poisonous making wearing air fed hoods compulsory they put out only a tiny amount of solvent into the air in comparison.
Luckily acrylic is still available here and it will give you a good finish but you have to be careful in applying it as the solvent attacks most things it is applied over and the solvent tends to dry out the moisture from the timber more. Having said that you probably won't have much trouble using it if you have used N/C. The main things to remember are thin it at least 60% thinner 40% clear and don't be in a hurry to apply coats. The longer you leave between coats the better ( at least 20 min - an hour is better) and only use about 5 coats.
If you put on 3 coats let it dry overnight, cut it back with 1200 wet then thin the mixture to 80-30 and spray the last couple of coats and leave it about a week in this weather you will get a better result.
Make sure the temperature is over twenty and stop if it blushes (goes milky) till the weather is better ( no rain)
It will buff up nicely after a week as it will be fairly dry and hard, if you find it a bit peely rub it wwith 2000 wet to flatten it and then buff.
Fantastic run down Durwood:2tsup: your advice on this subject is always terrific. (the same as your advice on me coloring the desk) Thanks:D
Yep OK, thanks for all the info.
I haven't sprayed lacquer at all before. Only ever sprayed poly U for furniture.
At the moment I'm tossing up whether to go for a shellac/oil/wax finish on this present project or to spray lacquer and I was in the paint shop to get some metho and thought I'd ask.
Getting a temp above 20 at the moment will be problematic. It has not been getting past the teens for the last couple of weeks. The other problem is that they seem to want to sell the stuff in 20 litre tins. Maybe the lacquer experiment can wait for the next job.
So what would that be?Quote:
Even A/L is banned you must now use a far better material.
I suppose that means that using shellac as a sealer isn't the best idea? The same company that does the lacquer (Concept Paints) has a sanding sealer that might be better if I went down that path.Quote:
you have to be careful in applying it as the solvent attacks most things it is applied over
Shellac would be ok as a sealer but as has been mentioned before you then have the durability problem ( especially with heat coffee cups etc if thats applicable)
The better materials are the 2 pack acrylic urethanes
you can buy acrylic lacquer in 4 litre tins go to a store that sells automotive paint. The best one is PPG Dulon AAA clear. Though any brand auto one will be as good or better than the Concept Paints.
If you can spray poly you can spray A/L.
Don't use auto lacquer its not made for timber.
Use a pre-cat furniture lacquer which is available in various gloss levels
Theres a few brands available, eg Mirotone, Haymes, Wattyl (from their industrial division not from a hardware/paint shop Croda (I think they were taken over a few years ago)
It's quite safe over shellac which incidentally is a good intermediate coat over a base that is incompatible with lacquer such as normal oil stains.
But try out lacquer based sanding sealer,
leaves other sanding sealers for dead.
its the best thing since deep fried bacon.
The problem I have here is that the local hardware and paint shops don't stock this sort of stuff because there's no demand for it. This one paint shop is trying to expand his services a bit - he's around the corner from a panel beater, so he's getting into automotive paints hence the connection with Concept Paints. They have recently released this range for timbers. They have 3 gloss levels in clear and then a range of coloured finishes - all in 1 or 2 pack.
If I go into Mitre 10 or somewhere and ask about Mirotone for example, they wont want to know me because there will be a minimum order quantity (if they can even get it). Wattyl might be an option.
But I just thought of something. A mate of mine runs a joinery, so he will probably either have some, or will be able to get it.
Echnidna,
I would be interested to know why you think auto lacquer would not be suitable for timber. Having done numerous tests comparing the two it stands up far better than N/C on timber.
Bob i have been using the auto lacquer from super cheap auto for around 15 months now (i stock up when they have there sales) and its the simplest thing i have used to spray and have never had a problem or a complaint. Lots of dining tables have been done and they all have stood up well.Quote:
Originally Posted by echnidna
Im sure i could do better than super cheap with the $$$ and quality, but it suits me fine:)
I NEVER use NC - I use precat furniture (acrylic) lacquer
I have used auto lacquer when I've been out of furniture lacquer.
and when a full gloss finish is acceptable
Yes it gives as good a finished product appearnace as furniture lacquer.
But is it as durable in the long term as furniture lacquer?
I note that if it was durable in the long term on wood the manufacturers wouldn't bother making a separate furniture finish
AFAIK Its not available in various gloss levels
Lig,
try Paintmobile in Preston or Dandenong, you'll get clear precat furniture lacquer (wattyl) at a very good price if you buy 20 litre drums
The sanding sealers much the same low price in 20 litre drums
acrylic lacquer (auto) is far better than furnature grade. It costs more to make the automotive stuff. It has to take a far greater beating outside in the sun. No need to add all the expensive UV filters etc in furniture no need for it. Even shellac lasts inside and it will only last a matter of days outside. Same rule applies as to all paints being equal there are lots of levels of quality, paint companies make cheap versions of all sorts of things solvents included.
I started in the paint trade in the late 50's before acrylic In those days NC was the only lacquer available A/L first became available here in 1962-63.
A lot of our customers owned Rovers, Jaguars, Rolls Royces which had NC as the finish on their wood dashs. We could refinish them with NC but it only lasted a short time so our old painter used a marine varnish which was a bit better but a problem in a dirty shop as booths were virtually unknown.
When Acrylic clear hit the market the problem was solved.
I ended up working for TAFE during this period, we taught clear finishing due to the Rovers etc./ At the college were had a rack on the roof and every year we got the students to put all types of finishes on the rack to see the results. A piece of timber with masked sections for NC, A/L and enamel soon showed which was the superior. The acrylic beat them hands down.
You can govern the gloss as the acrylic lacquer has a flatting agent you can purchase that allows you to change the gloss level to anything you want from full gloss to dead flat.
I must admit coming from an auto background I am a bit biased but as the house painters from our college always came to us for material when they had a particularly tough job and being able to not only paint all metals, plastics, timbers, glass, vinyls, leather with the products available to us I find it hard to use basically inferior materials.
Obviously if I'm working on a house then house paints are usually the go but when it comes to some things like the aluminium windows I quickly head for the auto paint it gives me years of extra service
Well, I think that Brisol up the road has the Concept Paints auto lacquer in stock in small tins, so maybe I'll buy a tin of that and some flattening agent (rings a bell, possibly from the catalogue) and see how it goes.
Must have a look for the flatting agent as I would just about bet auto clear is probably much cheaper than furniture clear
The flating agent varies in name depending on brand, usual names are flatting or matting agent or base.
Do you want to bet on the price?
Normally auto/aircraft and marine paints have a premium price compared top other paints.
Our paint was bought under Govt contract and the price still was way above retail for industrial lines.
Durwood, i get 4 Ltr of auto lacquer from Super Cheap for around $90 (less 20% on sale days) is that good or bad?
Awesome advice Durwood, thanks for the info. I think I will stick with the Auto Acrylic lacquer now. Haven't bought it for a while but I think it is similarly priced to say a Mirotone Pre-cat lacquer, I was just never sure if it was suitable for timber. Makes sense about being more durable and resistant to UV as it is designed to be almost always exposed to the sun, and its crystal clear to boot. People would be mighty pi$$ed if their car started to turn yellow after 6 months out of the showroom:C .
I assume it is also flexible enough to move with the timber during expansion and contraction? It must be because I know it doesn't dry as hard as 2-pac and I have never had any problems with the 2-pac finish cracking on a table top, cheers.
Hi Lignum and Matrix,
The super cheap lacquer would be OK for general wood work I personally wouldn't consider it for a car unless it was an old bomb. The top grade lacquer is about 30-50% more in price.
The auto paint is very flexable just look at a pranged panel on a car next time it really has to be crunched up to crack.
The normal test is usually to bend it around a 1/4 inch rod without fracturing. You can also add flexing agent to it, that has to be done on very flexible plastic parts.
Straight answer time then. It's a piece of furniture that will be in a bedroom. I've coved the panels tonight and want to start finishing them tomorrow. We got to 19 degrees today. I've got a brand new bag of shellac flakes and some 95% metho. So do I go with the shellac and wax, or do I buy some auto lacquer?
Use the shellac , you can always overcoat with lacquer for better moisture protection
btw Lignum, get a price for 20 litres of furniture lacquer,
I think you might be surprised.
Go the shellac, both shellac and lacquer will react pretty well the same in the same temp
Hi Durwood, can you use automotive primer or HiFill as a sealer on MDF to then overcoat with Auto Acrylic? I would like to have a play with some acrylic Candy's.:cool:
Hi Matrix,
Yes you can no problem, MDF has a waxy surface so its a good idea to give it a good wash with some Wax & grease remover or thinner first.
Just do a small area at a time wet it with one rag soaked and straight away wipe with a clean cloth.
If you are only playing around spray on the primers or if you intend doing something important thin the primer down more and brush the first coat on then spray the rest. You shouldn't need more than 3 coats of primer.
Do you know what to expect with candy colours?
I had a play with some lacquer yesterday. He only got in high gloss (forgot to tell him I wanted 50%) so it's not the finish I want for the current project.
I used the 2.0mm set up on the gun. I turned the air flow right down and opened the needle right up. I only waited until it was touch dry (a couple of minutes) rather than the 10 minutes recommended on the tin. It seemed to go OK but I got two problems:
1. Cover was a bit patchy when you look at it sideways into the light. But I think that was poor preparation. It has long streaky 'holes' in the surface that follow the grain.
2. When the last coat dried I had some pin-head sized air bubbles. What causes that?
did you rub back between coats.
pinholes can occur if the last coat hasn't cured properly
Nope didn't rub back at all, just sprayed several coats one on top of the other. Was just a test panel to see what it would look like. Maybe I didn't leave it long enough before the last coat. But it was actually a bubble or blister in the finish, as though air was trapped, or some sort of gas formed between the layers.
I think the streaky patches were because I didn't sand and seal properly. It looks like the finish has soaked in along grain lines, rather than a solid glassy film.
Give it a quick LIGHT dusting with thinners, and report back! :wink:
Cheers,
P
Righto!
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
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.Quote:
first read the instructions
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?
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?Quote:
Originally Posted by durwood
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.
Ahem..Quote:
So if I wanted to get a low sheen finish with the high gloss stuff, can it be done?
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:Quote:
Originally Posted by durwood
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
First off all it simply doesn't brown at all.....it ambers.Quote:
Originally Posted by durwood
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:(