About Painting the bike...

[Anonymous]

I was just peeping through some of the topics, and happened on the discussion of bike painting, which pointed back to an excellent article here on the site. Now, if any of you have painted using an air compressor and spray gun, what's the smallest (meaning affordable) size of air compressor that can be used to lay on a quality coat of paint? I was gonna go the spray can route until someone pointed out that that paint was uncatalyzed and would end up being damaged easily. So it will take me a little longer to restore "Lil Suzi" to her former glory. She means a lot to me, so I want to do this right. I also want to do it to last.
I really think my tank is beyond saving. It doesn't leak, but it looks really crappy. Bondo couldn't help it at all, as the amount it would take to level the tank would be too thick and would crack and vibrate out. But when I do find the right replacement tank, the whole bike is going to undergo a color change from the stock black, to something I haven't totally decided on. I was thinking blue metalflake or pearl, with some flames. But I want to start getting the right equipment now, so some winter, when she'd normally be sitting anyway, I can "dissassemble" her and make her look brand new again. I even want to paint the frame, as I've noticed rust around the welded sections. Also, does that mean it's time to look for a new frame, or can this one be salvaged? The bike is still sturdy on the road, and handles as well as it ever did, what, if anything, can I do with it?

Also, is there any special prep you have to do to just the regular unpainted plastic side covers? They are black plastic, but I don't want to leave them that color when I do the rest of the bike. Does it require special primer and paint for plastic, etc. Okay, that's enough questions for now. I think.

[Dink]

An 8 cfm compressor is enough to spray paint with, but only just barely and even then you need a special gun called a HVLP(high volume low pressure) a 12cfm is realistically the minumum you need.
Yes plastics do need a special primer, called an etch primer. It is a good idea to use an etch primer regardless though to ensure adhesion.
One other comment, have panel beater look at your tank, they may very well be able to salvage it for you, get a quote for them to beat it out and etch prime it for you and then compare that against what a replacement tank will cost you.
Dink

[Billy Ricks]

Be careful about using too small of a compressor. If they are too small the compressed air gets very hot and as it cools in the hoses it condensates causing watter droplets in the paint. Even a moisture seperator won't collect all of the moisture. The best type is a compressor with a tank. The tank allows the air to cool down and most of the moisture produced remains in the tank.

[Anonymous]

One other comment, have panel beater look at your tank, they may very well be able to salvage it for you, get a quote for them to beat it out and etch prime it for you and then compare that against what a replacement tank will cost you.
Dink

Thanks for the quick answers Dink. I'm afraid to have someone look at the tank. It's really in sad shape. These are pretty serious dents, caused by impact of the previous owners chest with it during an accident.
He had most of the other damage repaired, but stopped short of the tank, and properly straightening the handlebars which also bent. I figure a nice find on Ebay will probably be a better way to go. I bought a tank already on there, but I don't think it will work with mine, as it's from a GS450T, not an L like mine. I have a friend who does body work on cars, and he says the depth of the dents are the kind that required drilling of holes to pull the tank out, etc. Lotta work.

[Anonymous]

If they are too small the compressed air gets very hot and as it cools in the hoses it condensates causing watter droplets in the paint. Even a moisture seperator won't collect all of the moisture. The best type is a compressor with a tank. The tank allows the air to cool down and most of the moisture produced remains in the tank.

Okay Billy, I did some peeking at compressors on Ebay, but I'd just basically like to know things like, what HP should the motor be, tank capacity, etc. I wanna know what I'm looking at to do the job myself. I've had some experience with painting before (a 66 chevelle), but it was using someone else's equipment, and I don't remember how big his compressor was. I can't afford a big industrial compressor, so I want to know what the best size is for my purpose. I want to avoid all the pitfalls that everyone is warning me about. So I want to figure out what the best compressor is for me at this point. Not too small, not too expensive, but somewhere nice in the middle.

[Billy Ricks]

As long as it has an air tank on it then it should be enough to push a cup gun or small conventional. HVLP is nice but expensive. The little compressors that have no tank are the ones you shouldn't use at all.

[Griffin]

Well, I sell industrial air compressors for a living, ranging in size from 3 hp up to 2,000 hp (Yes, they get that big. The largest one I've ever personally seen was at a coal degasification plant and was 22,000 hp.) Anyway, the advice about getting a compressor with a tank is good. If you are only going to use it occasionally, the Campbell Hausfields at Menards are fine. Their duty cycle rating is only about 20% (meaning that for every minute they run, they will require four to cool down or the head will warp), but they will be ok for using a small paintgun.

One thing that people don't realize when they size a tank is that differential pressure across your regulator effectively increases the size of your tank. For example, the equation for storage is:

Storage = V X DP/Patm

Where:
V = Volume of tank in cubic feet
DP = differential pressure across regulator
Patm = atmospheric pressure (14.7 psi at sea level)

So, if you have a 40 gallon tank, it is 5.35 cubic feet of air. If that tank is pressurized to 100 psig, and the regulator is set to 40 psig, then you have:

5.35 X 40/14.7 = Storage

Storage = 14.56 cubic feet

That means that if you are using air at a rate of 8 cfm, you will have 1 minute and 49 seconds of usage before you dop the pressure in the tank below your regulator setpoint, assuming no air is entering the tank.

That's how people can use tools (intermittently) that require more air than their compressor can make.

As for water, you can let it drop out in the tank, but the air is still saturated with vapor, it just won't have any liquid water in it. Or, for home garages, I recommend that you install an inline desiccant type filter that will catch the small amount of oil carryover from the compressor and will remove a lot of water vapor from the air. They can be bought at any industrial air house (John Henry Foster, St. Louis sells them in Missouri) and will clean your air up lickety-split.

[Anonymous]

So a 2 HP, 6 gallon compressor that has a max pressure of 150 psi should do the trick? (I'm asking 'cause this one's on sale! 8) )

And what's HVLP mean :?

As long as it has an air tank on it then it should be enough to push a cup gun or small conventional. HVLP is nice but expensive. The little compressors that have no tank are the ones you shouldn't use at all.

[Billy Ricks]

So a 2 HP, 6 gallon compressor that has a max pressure of 150 psi should do the trick? (I'm asking 'cause this one's on sale! )

And what's HVLP mean

That will be fine for pushing a cup gun or small conventional with the gun seperate from the paint pot. HVLP stands for high volume low pressure. They use low pressure to push and atomize the paint. They are self contained units that are expensive and more than the average do it yourselfer needs. Having a compressor around comes in handy anyway.

[Anonymous]

As long as it has an air tank on it then it should be enough to push a cup gun or small conventional. HVLP is nice but expensive. The little compressors that have no tank are the ones you shouldn't use at all.

Cool!! Thanks for the input!!! I was beginning to think the spray can route was sounding better all the time.

[Anonymous]

Or, for home garages, I recommend that you install an inline desiccant type filter that will catch the small amount of oil carryover from the compressor and will remove a lot of water vapor from the air. They can be bought at any industrial air house (John Henry Foster, St. Louis sells them in Missouri) and will clean your air up lickety-split.

Wow Griffin!!! I am truly impressed!!! Thanks for the lesson in compressors, I think I can find the right one now. Thanks for explaining it so even I could understand it!!! I really like this place! You all will have me up to speed in no time!!!!! Thanks!!!!

[Anonymous]

thanks for the detailed info on compressors.
I've been considering getting some air tools, and was wondering what a reasonable (not bare) minimum to use a paint sprayer and perhaps an impact wrench. I'm a complete amateur and the duty cycle of 20% you mentioned will suit me fine.

thanks...Sam

Well, I sell industrial air compressors for a living, ranging in size from 3 hp up to 2,000 hp (Yes, they get that big. The largest one I've ever personally seen was at a coal degasification plant and was 22,000 hp.) Anyway, the advice about getting a compressor with a tank is good. If you are only going to use it occasionally, the Campbell Hausfields at Menards are fine. Their duty cycle rating is only about 20% (meaning that for every minute they run, they will require four to cool down or the head will warp), but they will be ok for using a small paintgun.

One thing that people don't realize when they size a tank is that differential pressure across your regulator effectively increases the size of your tank. For example, the equation for storage is:

Storage = V X DP/Patm

Where:
V = Volume of tank in cubic feet
DP = differential pressure across regulator
Patm = atmospheric pressure (14.7 psi at sea level)

So, if you have a 40 gallon tank, it is 5.35 cubic feet of air. If that tank is pressurized to 100 psig, and the regulator is set to 40 psig, then you have:

5.35 X 40/14.7 = Storage

Storage = 14.56 cubic feet

That means that if you are using air at a rate of 8 cfm, you will have 1 minute and 49 seconds of usage before you dop the pressure in the tank below your regulator setpoint, assuming no air is entering the tank.

That's how people can use tools (intermittently) that require more air than their compressor can make.

As for water, you can let it drop out in the tank, but the air is still saturated with vapor, it just won't have any liquid water in it. Or, for home garages, I recommend that you install an inline desiccant type filter that will catch the small amount of oil carryover from the compressor and will remove a lot of water vapor from the air. They can be bought at any industrial air house (John Henry Foster, St. Louis sells them in Missouri) and will clean your air up lickety-split.

[Anonymous]

Another option in some areas is "Your own garage" You can rent a spray booth with all the needed equipment. If you are quick you can get in and out for the minimum rate. They will have valve grinding equipment and all sorts of tools that you just sign out too. All you do is pay the hourly rate and the cost of any "consumables" Very cool. 8)

Steve

[Anonymous]

I used catalyzed paint in a spray can. My color dealer mixed the paint and the hardener in a spray can and I had to keep it in the fridge for maximun a month before I used it. The result is great. The quality of the paint is the same as on cars. Try a color dealer with speciality on car paint.

[Anonymous]

I used catalyzed paint in a spray can. My color dealer mixed the paint and the hardener in a spray can and I had to keep it in the fridge for maximun a month before I used it.

You had to refrigerate it for a month? You couldn't just use it right away? Explain more please, was it the cold that kept it from hardening in the can? Is that the only way you can keep it from hardening if you don't use it right away? Sure sounds a lot cheaper and easier than the whole compressor spray gun route, but If you'd ever seen my fridge, you'd know the paint wouldn't have an easy life there. LOL