Painting the brick

[The Mighty Gryphon]

Orange peel is really hard to prevent.  Best to just take your time and put on an extra coat.  Wait a day or two and wet sand with 2000 followed by 2500.  Then buff it with 3M Perfect It #2 &#3 on foam pads with a dual action buffer. 

If that was peeling, it is probably a combination of things.  First, some contamination before the basecoat.  You can't be wiping down too many times.  Then, possibly too much reducer in one of the coats and not enough flash time before the next coat.  High humidity can sometimes double or triple the time between coats. 

If it was a run, you need to go lighter on the coats of clear.  Give each one about 15 minutes to flow out and flash before the next.  Don't try to get too wet before the last coat, just put down enough to see a film of fresh clear forming.  Pay attention to how you are moving the gun.  Resist the temptation to go back in the middle of a coat to cover some dry spray. 

Factory paint is special with chemical compositions that are very poisonous, but work really nice.  It is also applied with guns and robots that cost hundreds of thousands of dollars in specially built paint areas with carefully controlled temperature and humidity.  Working as we do with cheap guns and safe paint we have to accept that there is going to be some extra work after the paint goes on.

As far as the comment on water based paint, a lot of shops have been using it for a while now.  The paint systems are actually pretty good, but require some adjustments to the application process to accommodate the slower evaporation rate of the water vs. the solvents used in the past.  Personally, the solvent based systems seem to work better for me, maybe because I'm used to them, or maybe because they're more tolerant of the conditions I'm painting in.  YMMV

[Filmcamera]

TMG I am embarrassed to admit the there is no clear coat involved so far, the runs and screw ups I have been getting are just in the basecoat.  Researching on the internet it seems the only way to fix runs and problems in the basecoat is to sand it back with 400 grit and start again from scratch.  Hence my growing frustration.

[The Mighty Gryphon]

You can do base in super thin coats, just barely dusting the paint on. 

On a lot of the parts I paint I use an airbrush to reduce paint waste from overspray.  Sometimes I set it up so light you have to look hard to see what is going out.  Don't be in a hurry, lay down 6-7 coats until there is coverage.  The important thing to remember is that you don't have to put down wet coats of base like you do with the clear.  All you need is to eventually get complete coverage.

[Martin]

+1 I've had better results using an air brush than spray cans. A couple of times a year Aldi have a small compressor air brush kit for around $100.00 Au. I kept looking at it but couldn't really justify it. Now that I've got spare bodywork I might be justified in getting it. I'm thinking (hoping) that it doesn't have the same problem my big compressor has with too much water in the air.
Regards Martin.

[Filmcamera]

ah ok so I need to set the paint volume really low  but keep the fan quite small if I am painting small parts or fan wide as well?


Thanks for the help, I am frustrated but am not the type to give up so I shall give it another go tomorrow - luckily the paint shop is close and open so I can keep getting more if needed - I will end up using 2 gallons to paint the bike at this rate!!

[The Mighty Gryphon]

That's right, throttle back the flow rate of the paint.  Don't worry about the width of the fan.  The important thing is that the coverage across the width of the fan is even.  Too wide and the center doesn't get as much as the ends.  Too tight and the center gets too much.

Technique is important too.  First pass with half the fan off the part, and then overlap each additional pass by one half the width.  Finish with half off the part.  Concentrate on keeping the fan perpendicular to the surface you're painting.  Start the flow before you are on the part, and sweep the fan across the part at the same speed all the time.


Martin, I use a Badger model 250 airbrush.  I get them used for $12 on ebay.  There are adapters that let me run them off my big compressor with the regulator set for 15-20psi.  Badger sells 2oz. bottles to replace the 1oz. bottles that come with the brush.  It's perfect for blending paint repairs or doing small stuff like mirrors and battery covers.  I also use it to supplement the gun for getting into tight places like the vents on fairing lowers.  The 250 is easy to set up and clean, and when they break it's no big deal.

[Martin]

Gryph before I moved to QLD in Victoria I used to run my airbrush off the Vespa compressor with no problems. However the humidity up here is a pain and water ingress has stuffed things up the couple of times I tried to use it. I really should look into building a water separator, I have also thought about getting some air supply cans from the local hobby shop, if they still sell them. I am going to leave my spare panels as they are until needed. I've painted whole bikes and Go Karts with solid paint colours with no problems. Not real good with big jobs with metallic paints. Down south it wasn't a problem as I had a sponsor who had a paint and panel shop. I should have had lessons when I had the chance, big missed opportunity.
Regards Martin.

[The Mighty Gryphon]

Moisture shouldn't be a big problem.  There are disposable in line air dryers available for around $4-5.  You can put one at the end of the air hose where the airbrush connects.  Shoot the paint, and throw it away when you're done.

https://www.harborfreight.com/disposable-inline-moisture-filter-68224.html?_br_psugg_q=filter

[Martin]

Thanks Gryph I'll have a look when I decide to finally, maybe, possibly have another go at painting metallic paint.
Regards Martin.

[milq]

+1 I've had better results using an air brush than spray cans.

Agreed, lots more variables to tinker with to make things just right. I do some bake-on firearms finishes from time to time and airbrush is the way to go.

[BlitzenGruv]

Just one question, is the factory paint enamel or lacquer?

[The Mighty Gryphon]

Just one question, is the factory paint enamel or lacquer?

My guess is that it's a 2K polyurethane from BASF.  Similar to DuPont's Imron.  Really nasty stuff, but tough as nails.  We used similar stuff to paint boats.  Even outdoors, we needed full respiratory gear.

Most of the paint available for repairs is acrylic enamel.  It's not as tough as the factory stuff, but is safer to work with and less dangerous to the environment.

[BlitzenGruv]

Thanks Gryph.
Once I get the fiberglass repaired I will need to paint the fairing. I have used Duplicolor Exact Match in some Toyota shade to touch up a mirror. That's lacquer, but it hasn't reacted badly with the existing paint. Actually I held one side panel up next to my Rav4 and that color is pretty darn close. Gotta be easier to find than 680 King's Blue.
Duplicolor also makes a metallic blue in their Paint Shop line. That's also a lacquer, but with a urethane clear coat it should hold up.

[The Mighty Gryphon]

Blitz, clear it with SprayMax 2K clearcoat in a rattle can.  Shake the hell out of it before and after you punch the red button.  Follow the directions for flash and dry times, don't try to rush the coats. 

After a couple days, wet sand any runs and orange peel with 1200 followed by 2000 or 2500 and buff up to a nice shine. 

Two cans should do the fairing and maybe have a little left over.  Once the button is pushed the pot life is rated at 48 hours.  That can be extended to 5 days by putting the can in the freezer to slow down the chemical reactions.

[Filmcamera]

Progress, at least I think so.


No runs this time.  However quite a lot of orange peel, is this normal in a basecoat or does it mean I went too far in turning down the paint flow?  I did three light coats.

[The Mighty Gryphon]

What are you using for paint?  I have never seen a base coat go on with a shine like that?  Are you using a base/clear system? 

What speed reducer are you using?   I'm thinking a slow reducer is what you should be using. 

How much are you mixing?  Most of the base coats I use have a 1:1 reduction, 1 part paint to 1 part reducer.

Are you adjusting the delivery to have a spray that lays down a semi-transparent layer of paint.  The gun should be almost putting out a mist of invisible droplets that makes a very light layer of paint with each pass.

How many coats are you putting on?  I get my best results with at least three VERY LIGHT coats. 

I don't know what gun you're using, but I would guess that you need something in the range of 40-45psi or 3 bar of pressure.  Adjust the regulator with the gun's trigger pulled all the way in.

I would strongly suggest that you spend an evening on YouTube watching videos explaining how to set up a paint gun.  There is a lot of good information there.  Look for similar tips among many videos.  That will help filter out the weird stuff. 

Right now, try wet sanding what you have put down with 1000-1200.  That will get rid of the orange peel and provide some "tooth" for the clear.  Be careful not to sand through the edges, in fact, you might want to avoid hitting them with any more than a single pass to scuff them a just a little bit.

[Filmcamera]

OK let me go through the questions and try and answer them one by one.


I am using standard reducer at a 1:1 ratio


The paint is called Yaku maxytone automotive paint and the reducer is by innocolor. They both came from the local professional automotive spray paint store as did the clear which I have not even opened yet.  I actually took the brick to the store with me and spoke to the guy who mixed the paint up for me and that is what he gave me.


Yes, I would say the paint flow is pretty fine, I had to double check anything was coming out at all.  The gun paint volume screw has a total travel of four and a half turns and I have it two and a half turns in towards fully closed.  Before my next attempt I will take a quick video of the fan and paint quantity to post with the results


The fan I had set to about half way of the full travel of the adjusting knob as well.


I put three coats on the belly pan in the video.  I think that came to 3 fluid ounces of paint plus three more of reducer for the K1100 style belly pan.


I am using a Astro Evo-T LVLP gun with a 1.4mm tip that runs at 1.9 bar.


I have watched a ton of Youtube videos but will watch some more.


I will try and other panel tomorrow with even less paint flow.


Thanks very much for all the help. 

[The Mighty Gryphon]

I assume the reducer is the right one for the temperature you are painting at.  I'm guessing the temperature is running 30C.  At that temperature it's usually recommended to use a slow reducer. 

I have no experience with the paint you are using.  I have to look up the data sheet on the interweb.

Same with the gun.  The pressure sounds a bit low, but I am used to cheap guns that require more pressure for good atomization.  Are you reading the pressure at the gun, or at the compressor?  What size hose?  Pressure drop with a lot of flow can reduce the pressure at the gun by as much as 0.5 bar which can really mess up the atomization even if the flow is throttled way back.

6oz. of reduced base sounds about right for the belly pan.  It's odd that it looks so thick in the video.  I am at a loss at how to explain it. 

I will do some reading this evening.

[Martin]

Practice on something else until you are comfortable with the results.
Regards Martin.

[Filmcamera]

I have a pressure gauge on the base of the gun and am reading the pressure with the trigger fully depressed,  The 1.9 bar is what the manufacturer recommends for the gun.  It is far from a high end gun but nor is it a total cheapo piece of garbage - it was about $110.


https://www.amazon.com/Astro-EVOT14-EuroPro-Forged-Plastic/dp/B00HZBX0VI/ref=sr_1_2?dchild=1&keywords=astro+evo&qid=1587677066&sr=8-2


The video was taken very close up, maybe two or three inches from the surface, also the paint was laid down this morning was maybe it will float out a bit more overnight (though I doubt it)


One other thing I am trying to keep the gun an even 6-8 inches from the surface when I am spraying.


The temp when spraying was not as high as 30C but close, maybe 27C with pretty high humidity. I am painting outside under an awning with plastic hung up on the sides.

[Trash Hauler]

High humidity can be a problem even with the higher temperatures. I painted in the top end of Australia and orange peel was a problem 9 months of the year, it was only the dry season with the humidity down around 50% that we could get good results without a booth.

[Filmcamera]

honestly I can live with a little orange peel - as long as there are not huge runs and sags I think it will be ok.  I will do a couple more panels in the morning, but maybe try a little later in the day when the heat has burned off more of the morning dew etc - worth a try anyway

[The Mighty Gryphon]

Is the paint Yaku or Yatu?  I can find a Yatu Maxytone automotive paint.  Made in China.  Is that what you have? 

https://yatu-car-paint.en.made-in-china.com/product/DXfQdwLlAYcS/China-Maxytone-1K-Basecoat-Car-Paint.html

Crossover from mid to slow reducer is 30C.   

No idea of what they recommend for mixing ratio.

Pressure is listed as 2.2 to 4.4 kg/cm2  which I think is 1.9 to 3.8bar(28 to 55psi).

Flash time 15-20 minutes between coats.

Found the gun on Amazon, Looks like a decent mid range gun.  Looking at questions it appears some users are getting good results at a supply pressure around 40-45psi. 

Martin has a good idea for getting some practice on a scrap.  In the boat yard we had a piece of heavy duty glass about 9x12 inches.  When we set up a gun we test shot on the glass.  The glass makes it easy to see what the pattern is, and it's easy to wipe clean with a rag wet with solvent.

About gun settings, do you have the air volume control wide open?  That is the knob next to the air inlet.  If not, open it up.

Set the pressure at 35-40psi with trigger pulled all the way back.

Set the fan control to about mid-range.  Close off the flow control, and open it up about 1 turn.

Shoot a quick burst about 8 inches from a surface.  A newspaper will work.  Begin to adjust the fan and the flow to get a fan width about 8 inches with a very light coat of paint.  Open the flow and adjust the fan so a quick burst makes a vertical line 8 inches long, about 2 inches wide and has very uniform paint delivery over it's entire length.  No blob in the middle, or heavy out at the ends with little in the middle.

Take a sweep with the trigger pulled and see if you leave a nice uniform film with no horizontal streaks.  Fine tune the fan to get rid of the streaks if there are any. 

When the fan leaves a uniform pattern when you sweep over the surface take a really close look at the paint film.  Are the droplets almost invisible?  You may find you need more pressure to fully atomize the paint. 

This brings us to your compressor.  The gun appears to require 9.5 to 11.5cfm to work properly.  That is a lot of air.  How big is the tank on your compressor?  It usually takes a pretty big compressor to supply 10-11cfm for any length of time.  You can get by with a smaller unit, but you really want to be able to lay a coat on your biggest part before the pressure at the gun drops below 40psi.  Among other things, you have to keep an eye on the pressure and stop when it drops below the setting on your regulator.

If you find yourself running out of air, you need to sweep the gun faster and use more coats, otherwise the coverage and atomization won't be uniform from the start to the end of the coat.

[The Mighty Gryphon]

About air delivery:  If your compressor fills that tank to 120psi and your regulator is set to 45psi, a 20 gallon tank will hold about 5-6 usable cubic feet of air. 

At 10cfm that will give you about 30 seconds of spray time before you have to stop to let the compressor catch up.  A bigger tank gives you more time, and a smaller tank will give you less.

Putting down base coat, 30 seconds should be more than enough time for any parts you will be painting.  For clear, you can still do it, but you need to be very careful with how fast you are sweeping so you don't run out of air.  For the clear you might want to set up the gun for maybe 30-35psi.  The lower the pressure, the less airflow, and the more usable air in the tank. 

[Filmcamera]

Yep that is the paint I have.


They shop I brought the stuff from actually wrote 1:1 on the reducer can.


I will change the supply pressure, I have it set higher than that.  The air inlet was not wide open, I will do that.  Basically there are three ways of controlling the air pressure from the compressor. The first is on the compressor itself and is set to 95 psi because that is the most my other air tools are set for. 


The second is on the pressure gauge I have installed on the bottom of the gun and the third is on the gun itself.  I will open up the one on the gun and use the one on the gauge to set a pressure of 1.9 bar when the trigger is pressed.


The tank is 120 gallons but I am not sure of the cfm, I got it used and have not been able to find info on the specific model on the web. However it seems to run at around 100 psi when I am shooting, it is filling almost running but the pressure does not drop that low.


I do have a sheet of paper taped up to test fine and paint etc, I will do a video tomorrow before shooting again.  One of my issues is because I am new and do not have much space I am painting only one ro two parts at a time then have to clean the gun etc before trying again so keeping the settings consistent is an issue.


I think I need to leave more time between coats as well, I did the three today as almost one constant coat starting on oen side covering the part giving it a quick look then doing it again.  I will leave more 10 minutes between tomorrow.