Painting Questio

[basher]

Spraying me zenith, i cant be bothered to strip it as it is anodized so will have to go get some costic soda. You think it should be fine to spray on top of the anodizeing if a rub it down with some sand paper and ruff it up? Also when masking will i need to put on one layer of masking tape or more like 2/3 to make sure no paint gets through?

[duane]

Hi,

Can't help with whether or not you can paint directly on anodizing, but for spray painting in general one coat of masking is fine you should then aim for at least one 'dry coat' and finish with at least one 'wet coat'.

For masking you can use automotive masking tape or model making tape, but should avoid the type used by decorators as its fine for emulsion paints but the harsher chemical make up of a spray paint may bleed through it.

A dry coat is where you spray from a distance so that the paint is almost dry by the time it reaches the surface to be painted. What happens is that the drying paint forms a rough surface which later layers of paint will form a better bond with, it also provides a much better seal around your masking, if you spray the first coat too wet, it will wick its way into any flaws you have in your masking. A dry coat should look as if it has a dull rough finish, you build up your colour coats on top of this, once you get close to the colour depth that you want, you can spay one or more wet coats, for the wet coats you spray closer so that the paint is still well disolved as it hits the surface. Wet coats are a real art, and the name is a little misleading. You want to spray closer to the surface, but not spray too heavily - i.e. not too much paint in one area. The idea is that the paint should hit the surface while it is still wet, this allows all the individual paint droplets to recombine on the surface and give you a glass smooth finish which looks wet and glossy even when its dry. Its important to note that wet coat refers to the look of the finish rather than "spray shit loads in a really thick wet coat" - that will look crap and probably run or bubble.

The big secret is future floor polish - you can get this in most super markets, its sold as floor polish, but is actually a really thin, high gloss clear acrylic paint that will give your finish a high gloss hard wearing seal. Future is so good, it can even turn a fairly crappy rough paint job into a high gloss finish. If you have an airbrush spray it on otherwise brush it on, the formula is so good your brush strokes will even flatten out and it costs a pound for a life times supply from Sainsburys.

If you use google to look up spray and 'orange peel' you will find everything you ever wanted to know about spray paint and more,

The last thing to say is check all your sprays and future are compatible on a test peice first - so sprays can attack each other.

Hope that helps

Duane.

[darrenhopper]

I've yet to bother masking anything I spray. Usually just stick some bolts in the threaded bits & stuff newspaper in the Headtube & BB shell.

I imagine roughing up the frame will probably work but to be sure try throwing some decent primer at it first.

Do it somewhere out of the way to begin with in case the paints react with one another & be sure to use the same brand paint as your primer.

Often different brands will react with one another & just bubble off the piece you're painting.

Breast of luck!

[AdamR28]

Unless someone's anodised that frame before you got it Hudson, it's painted

PS: Beast of a post Duane, all what you're saying makes complete sense yet I hadn't thought about the dry/wet coat thing before!

[King C]

I didnt think Zenniths were anodised either. Anyway, don't bother nitromorsing it and stuff, Just sand everything down so that its smooth and most of the light scratches have been removed the proceed with spraying.

[Elliot]

That would be well worth adding to the Wiki dude!

[basher]

Thanks for the essay dude i never had thought about the dry wet coat thingy. I was going to use laquer as i used that on me last frame but i think ill try the floor polish. Im still not stripping it now ino its paint its way to much hassle and im lazy.

[Tomm]

Yeah, that's some good knowledge Duane, I never knew any of that.

The last thing to say is check all your sprays and future are compatible on a test peice first - so sprays can attack each other.

This I can testify about - it completely screwed up my first paint-job. I used random spray paint bought from a DIY shop, with Halfords laquer and the two reacted badly, the paint all bubbled up.

If you get all the paint from the same place (E.g. Halfords), it ought to be ok though.

Back on topic, just roughen up the surface a bit with some coarse wet+dry, then some finer stuff.

[duane]

Andy asked a question about Future Floor Polish so I thought I might as well add in a response here along with everything else I ever knew about spray paint, Futures near the end so I hope you like reading -

[Just viewed the post and none of my text diagrams work, will have to live with that for now.]

Spay paint is made up of many different compounds that do different jobs between the paint leaving the can and you getting a nice shiney new paint job.

To name a few of these -

There is the propellant that gets the paint out off the can,

The solvent that keeps the paint liquid inside the can and for a short while after it hits your frame,

The coalescing agent that allows all the individual liquid paint droplets that left the can to merge into a single shiny paint surface when they hit your frame.

Finally there’s the pigment which gives your paint the colour

There are loads of others too, but these are the biggest contributors to the appearance of your finish.

Over time all of these chemicals separate in the can, so the first thing you need to do is get them all back together again. Anyone who does a lot of spraying will tell you that you will get a better finish if before shaking the can to mix all of these chemicals and before each coat, you first warm the can in a bucket of warm water. I am not telling you to do this. The side of the can will tell you not to do this. Find someone else on the internet that is telling you to do this then do it and blame them if it blows up ;-)

Should you ignore my advise against warming the can, it will do two things, firstly all the chemicals will be more active at the slightly higher temperature so that they will mix more easily and secondly the pressure inside the can will be raised. These two factors together give you a much better finish as a result of the paint being a more uniform mixture which is sprayed more finely and quickly due to the higher pressure.

But like I said don't do it.

Before spraying you must thoroughly mix the paint by shaking the can for a few minutes.

Its always a good idea to test spray something just before you start on your frame, try and test spray at the same distance and speed as you intend to spray the frame. With practice you can watch the finish forming as your spraying, you can then move the can closer or further away as you go to get the wet or dry coat that you are aiming for.

Whether you are spraying a wet or dry coat, the main thing that you want to avoid is an 'orange peel' finish. The name orange peel comes from a pitted finish that looks like the surface of orange peel. This is normally due to the paint not being well mixed, being at too low a temperature to flow or being sprayed at too low a pressure. If you get orange peel, its best to start again, rather than try and cover it will more coats of paint.

The surface of an orange peel finish is similar to a good dry coat, but at a much larger scale

Orange peel

__ __

/ \ / \

/ \___/ \___

A good dry coat

/\/\/\/\/\/\

The difference is that the irregular surface of an orange peel finish is easily visible and the visible peaks and troughs are too big to be filled by a decent wet coat. The fact that your first coat has resulted in an orange peel finish guarantees that the condition of the paint will not give you a good wet coat should you decide to go ahead an try one. You will just be putting c5ap paint on c5ap paint resulting in even more c5ap paint to get off before you can start again.

With a good dry coat, the surface irregularities are too small to see and are easily filled by a good wet coat. A good dry coat should appear level, but have a matt finish - maybe having the appearing of very fine grit if its the first very dry coat and you just want to seal all your masking. After a first dry coat you should be aiming for matt layers of colour rather than the excessively dry coat which may be used as a base and to seal masking.

When you spray your final wet coat over the dry coat at a microscopic level you get the following.

__________

/\/\/\/\/\

Environmental factors like the temperature and humidity have an effect on how your wet coat will appear. In an ideal world the weather will be perfect for your brand of paint and this is where then story ends. However if the weather is very hot, your paint will be drying before it reaches your frame and every coat will look like a dry coat, stop spraying, the paint is not magically going to changes its behaviour just because you want it to and more paint always equals more problems.

Unfortunately the same finish can result if the temperature is too cold, this time its because all of the chemicals are less active at the lower temperature so the paint won't be so well dissolved and the coalescing agent can't do its job.

In either case the result is the same and you have a number of options to rescue your finish -

1) Use successively finer grades of wet and dry paper to cut the surface peaks back to a level gloss finish

2) Use a polishing compound (t-cut or similar) to cut the surface peaks back

3) Use Future floor polish to fill the troughs

in 1) and 2) we are cutting back this

/\/\/\/\/\

to this

________

in 3) we are living with

/\/\/\/\/\/\/\

but getting a gloss appearance through Futures ability to do this

__________

/\/\/\/\/\/\

Technically the best highest gloss finish is either 1) or 2) finished by 3), however you sometimes loose a little bit of colour depth. Approach 3) seems to result in a nice gloss with a richer colour and less effort.

I think that the loss of colour depth in 1 and 2 finished by 3 is because a high gloss surface reflects lots of light before it gets down to the paint layer which is also high gloss and reflects a lot of the light, so in effect you get two layers of light reflected before your colour layer, where as in 3) only one layer of light is reflected before the colour layer. That might not be strictly technically correct, but it sums up the effect.

Future is also a hardwearing clear finish that will protect you colour coats whichever route you go. The name is misleading, its not a polish, just a very high gloss clear acrylic lacquer. In the UK Future is sold as Johnsons Klear, have a look in the kitchen, you might already have some, although the fresher it is, the better it works. You can get it in the floor cleaner sections of most supermarkets.

Future can be applied with either an air brush or a paint brush.

Lastly some generic tips which might save someone some time -

1) If you are masking anything, use a dry coat to seal the masking.

2) I only use primer if the original surface is a vastly different colour to the finish I want or if there is filler etc that would show through the colour coats - but test your paint first, you might not be able to get away with this.

3) If your not using primer make sure you get a couple of good dry coats down to build your colour and bind the paint to the surface.

4) If you are using more than one colour even if they are from the same manufacturer, test them for compatibility, that’s both chemical compatibility and appearance, dark colours always show through light colours. Also when Halfords make Vauxhall red their main concern is that it matches Vauxhalls colour not whether it is chemically compatible with Halfords Ford Mexico Orange.

5) If you want to put your name or anything else on your bike, find someone with a PC Vinyl cutter, its a machine that takes a graphics file and cuts a vinyl mask which you can then use to put custom graphics on your frame.

6) If at any stage you get an orange peel finish stop - remember more c5ap paint just equals more c5ap paint.

7) Test your spray every time before you use it, even the time of day makes a difference to how the paint behave. if you have done everything else right, but the finish isn't what you expect, it could be down to the weather, just be glad your did the test and try a dryer, colder, warmer etc day or even a different time of day.

8) If your wet coat goes on nicely but dulls as it dries, this is down to the weather and can be rescued using a polishing compound, very fine wet and dry paper or future as described earlier.

9) If you use the liquid floor polish as a gloss coat, try and make sure you let it dry in a dust free environment dust trapped in a gloss coats looks much worse than dust in a colour coat which is bad enough.

10) if you do insist on warming your spray cans, find someone else who recommends it and follow their advice as to sensible temperatures. An exploding aerosol full of flammable and highly toxic chemicals is a very bad thing. Remember I told you not to do it.

11) Wear a mask when your spray, coating the inside of your lungs with paint will not do your endurance or life expectancy any good.

Ill say it again Future is sold as Johnsons Klear in the UK,

That’s all that I can thing of for now

Good spraying

Duane.

Edited July 19, 2007 by duane