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Puzzled: paint grains / flakes at some spots

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  • Member since
    January, 2017
Puzzled: paint grains / flakes at some spots
Posted by EvgO on Thursday, February 02, 2017 8:04 AM

Hello renowned painters! I've got an issue I can't figure out. This is my first ever model car, although I've painted other stuff before.

I'm using an airbrush (about 18 psi) and automotive paint (custom mix I ordered at the local auto paint shop), which I thinned. 

These flakes or dust or residue somehow gather at raised areas of the car, see for yourself:

What is it? How do I deal with it? 

Also, when I wet sand the body, I tend to sand off the raised panel lines. Is it because the paint is not thick enough or I didn't give it enough time to cure (48h)? 

Thanks!

 

Tags: auto paint , dust , grain , paint
  • Member since
    December, 2003
  • From: Nova Scotia
Posted by Bainford on Thursday, February 02, 2017 8:38 AM

Yes, a curious result indeed. I'm not an expert on such things, but my guess is the paint was applied too dry. The pressure certainly does not seem too high. You may need to experiment with opening up the paint flow a bit and/or painting closer to the subject. These are my guesses, so perhaps a more knowledgable painter will chime in.

When painting a car body I always apply extra paint to the raised body lines; a couple extra coats on just the fender edges, raised panel lines, etc before I begin to cover the whole body. Also when polishing I will sometimes apply a thin strip of masking tape to these raised body lines and edges, polish as normal, then remove the tape just before the final polishing step, taking care to avoid bearing down on the raised lines.

Also, it looks like you are using a metallic paint. Metallic paint should not be polished directly. Apply a clear coat or two and then polish that. Polishing a metallic paint will cut through the metallic particles, exposing them and making the paint seem blotchy and uneven in colour.

Power matters in the straights.
Lightness matters everywhere. - Colin Chapman

Trevor

  • Member since
    January, 2017
Posted by EvgO on Thursday, February 02, 2017 8:46 AM

Bainford

Yes, a curious result indeed. I'm not an expert on such things, but my guess is the paint was applied too dry. The pressure certainly does not seem too high. You may need to experiment with opening up the paint flow a bit and/or painting closer to the subject. 

I actually thought that as well and upped the thinner ratio and painted closer. It gave the same effect, however. 

Bainford

When painting a car body I always apply extra paint to the raised body lines; a couple extra coats on just the fender edges, raised panel lines, etc before I begin to cover the whole body. Also when polishing I will sometimes apply a thin strip of masking tape to these raised body lines and edges, polish as normal, then remove the tape just before the final polishing step, taking care to avoid bearing down on the raised lines.

Also, it looks like you are using a metallic paint. Metallic paint should not be polished directly. Apply a clear coat or two and then polish that. Polishing a metallic paint will cut through the metallic particles, exposing them and making the paint seem blotchy and uneven in colour.

 

 
Those are great tips! I also didn't know that metallic paint should not be sanded directly, but it makes so much sense. Thanks! 
  • Member since
    August, 2016
  • From: Wisconsin
Posted by jwrass14 on Thursday, February 02, 2017 8:59 AM

EvgO,

I have been a professional 1:1 painter (see profile) for 45+ years this is what I see and recommend.

I like the fact that you are using a Airbrush!

I would turn up your air pressure up a bit to 25-30 psi and perhaps reduce your paint a bit more. Even the finest Metallic settle fast, always keep your Metallics in suspention by mixing often! The specs you see is a direct result of Metallics settling!

Here's a body shop trick that is often used with Metallics. Once you reach your acheved color coverage cut your color with 50% clear and apply two more coats with this mixture, this proceedure will even out your finish. Apply two more coats of straight clear as a barrier coat

Never directly sand on a Metallic finish as it will disturb the flake orientation and cause streaks and burns, always apply clear after painting metallics as a barrier for future sanding.

As far as sanding off the raised areas... Yes you do not have enough paint and proper proceedure as discribed above... I know it's hard to stay away from the raised lines on such a small surface, however slow and methodical sanding is key here, try not to sand with paper the rasied areas as they have a natural shine. Sand with paper and follow lightly the whole surface with a greg scuff pad.

I hope this helps!

Jimmy "RASS"

 

"I Have Flying Monkey's And I'm Not Afraid To Use Them"

  • Member since
    August, 2016
  • From: Wisconsin
Posted by jwrass14 on Thursday, February 02, 2017 9:06 AM

Treavor makes a great point with regards to protecting edges with masking tape before polishing. This is a common practice on 1:1

"RASS"

"I Have Flying Monkey's And I'm Not Afraid To Use Them"

  • Member since
    January, 2017
Posted by EvgO on Thursday, February 02, 2017 12:27 PM

jwrass14

EvgO,

I have been a professional 1:1 painter (see profile) for 45+ years this is what I see and recommend.

I like the fact that you are using a Airbrush!

I would turn up your air pressure up a bit to 25-30 psi and perhaps reduce your paint a bit more. Even the finest Metallic settle fast, always keep your Metallics in suspention by mixing often! The specs you see is a direct result of Metallics settling!

Here's a body shop trick that is often used with Metallics. Once you reach your acheved color coverage cut your color with 50% clear and apply two more coats with this mixture, this proceedure will even out your finish. Apply two more coats of straight clear as a barrier coat

Never directly sand on a Metallic finish as it will disturb the flake orientation and cause streaks and burns, always apply clear after painting metallics as a barrier for future sanding.

As far as sanding off the raised areas... Yes you do not have enough paint and proper proceedure as discribed above... I know it's hard to stay away from the raised lines on such a small surface, however slow and methodical sanding is key here, try not to sand with paper the rasied areas as they have a natural shine. Sand with paper and follow lightly the whole surface with a greg scuff pad.

I hope this helps!

Jimmy "RASS"

 

 

Very helpful, thank you! Too bad that none of the gazzilion of tutorials I've read covered this, but learning is part of the hobby, I guess.

Will try your recipe.

 

Any way to fix this, apart from stripping paint?

  • Member since
    August, 2016
  • From: Wisconsin
Posted by jwrass14 on Thursday, February 02, 2017 3:01 PM

EvgO,

If you are not to particular about the detail lines, scripts etc I woundn't strip it, this is what I would do, You have a good base with what you have layed down, I would sand the body with 800-1000 grit wet followed by a grey scuff Pad. Try not to sand to the primer.

Painters tip... Place your water in a container with a few drops of dish soap, place your paper in the water about a hour before you start sanding, the dish soap acts as a lubricant almost eliminating paper clog of paint and softens the paper as well.

This is where it may get tricky.... Always something right!

There is a possibility you could have a reaction of recoating (however slim) as in sand scratch swelling and or lifting.

In an effort to eliminate any of those problems do the following:

On your initial coats spray them medium wet and double the flash times (wait) between coats. You can gradually increase the wetness of the coats as the initial coats act as a quasi sealer, continue to paint and clear, maintain double flash times though.

If this doesn't work in the pond it go's! If that's the case all you have wasted is a bit of paint and time, however you have gained some valuable practice and experience.

Happy Trails

Jimmy "RASS" 

 

"I Have Flying Monkey's And I'm Not Afraid To Use Them"

  • Member since
    January, 2017
Posted by EvgO on Friday, February 03, 2017 7:26 AM

Will try to execute your instructions and report back in a while :)

  • Member since
    January, 2017
Posted by EvgO on Sunday, February 26, 2017 5:08 AM

Ah, the misadventures continue! 

 

I've sanded the residue off and recoated with a mix of clear. It did fix the issue, so thanks a lot for the useful advice!

I've encountered a new problem. While sanding, I've ruined the hood, so had to strip it and re-paint it (twice...). The plastic was undamaged and smooth. The surface, however, looks like this:

Its grainy as hell. The car, oddly enough, looks similar, mottled, but the surface is smooth. I'm guessing I've messed something up with the metal particles again. Any ideas would be welcome. 

  • Member since
    August, 2016
  • From: Wisconsin
Posted by jwrass14 on Sunday, February 26, 2017 7:19 AM

Ah, The learning curve.....Don't get frustrated and most of all don't give up!

I have confidence we can get you where you want to go if you provide some more information. provide the following:

What air pressure are you spraying at?

What is your reduction rate?

Explain the best you can your paint proceedure...i.e. Distance, Speed of passes, Wettness of surface after you make a pass, overlap.

On my end the picture doesn't show to much.... at first glance it appears the paint may not be reduced enough and you are not laying the paint down wet enough.

What type of Airbrush are you using and what size is the fluid nozzle and needle?

Jimmy "RASS"

"I Have Flying Monkey's And I'm Not Afraid To Use Them"

  • Member since
    January, 2017
Posted by EvgO on Sunday, February 26, 2017 7:40 AM

Thanks for spending your time to help me sort this out, Jimmy! 

Since I'm battling this project for about two months already, I hope that I'm beyond the point of frustration :) Just want to do it properly. 

Now, the info:

- Air pressure: 28 PSI;

- Reduction rate: about 1 to 6 (paint to thinner). Afraid to go any thicker;

- Spraying distance: about 10 cm (4 inches) - that's the closest before the paint goes on completely wet;

- Speed of pass: I'm going about as fast as I can so that the paint doesn't run;

- Surface wetness after a pass: a bit shiny, dries rapidly. Any wetter and it starts making "ripples" if I go too slow.

- Airbrush: a generic RDG Tools airbrush. It's on the cheaper end of the spectrum and did fine back in the time when I was spraying acrylics on wargame miniatures;

- Nozzle diameter: 0.3mm. Probably a tad too small, but my larger nozzle broke.  

- Fluid nozzle: no idea, the manufacturer's website doesn't list it either. Looks wide enough though. 

 

Now, having written that all down it does seem that I may be layering it on too dry and the small nozzle size contributes to that. The fact that I spray so close to the surface should have been a giveaway - that's my theory at least. 

I can't get a better picture, unfortunately, since I don't have a camera presently, only a phone. 

  • Member since
    December, 2007
  • From: Portland Oregon: Tree Country. Most beautiful area on the West coast.
Posted by Treehugger Dave on Monday, February 27, 2017 9:45 AM

See these kind of problems here often over the years. Been here since '07.

I too have painted 1 to 1 cars - since the mid 70's, built model since 1950 as well as airbrush. In your case, air pressure is too low, paint isn't thinned enough, and you aren't keeping the metallic mixed nearly enough. Metallics settle almost instantly, so I swirl the paint to mix after 2 passes.

Oh yeah, guy's hate this part and call me a liar and other things, but I shoot with the largesT spray nozzle I could find for my airbrush, and I never shoot below 60 PSI - Yeah no kidding. Works great for urethane filler primers too.

My walls are plastered with awards for my cars including multiple best paint. You can't argue with success - Well, I guess ya could Laugh.

I love Mecum Auctions and Barrett/Jackson auctions and what would I do without Ebay.

 

 

                                     

 

 

  • Member since
    August, 2016
  • From: Wisconsin
Posted by jwrass14 on Monday, February 27, 2017 3:14 PM

[quote user="Treehugger Dave"]

See these kind of problems here often over the years. Been here since '07.

I too have painted 1 to 1 cars - since the mid 70's, built model since 1950 as well as airbrush. In your case, air pressure is too low, paint isn't thinned enough, and you aren't keeping the metallic mixed nearly enough. Metallics settle almost instantly, so I swirl the paint to mix after 2 passes.

Oh yeah, guy's hate this part and call me a liar and other things, but I shoot with the largesT spray nozzle I could find for my airbrush, and I never shoot below 60 PSI - Yeah no kidding. Works great for urethane filler primers too.

My walls are plastered with awards for my cars including multiple best paint. You can't argue with success - Well, I guess ya could Laugh.

 

Evg0,

I'm glad someone else has weighed in Thanks Dave!

I agree in most part what Dave has offered, If your reduction rate is 1 part paint and 6 parts reducer you are way over reduced on your paint, typically reduction rates are 1 part paint to 1 to 11/2 parts reducer as a rule of thumb, However I use the manufactures recommended rate of reduction and adjust from there. 

Dave is absolutely correct in that metallics settle fast. It is imperitive to keep them in suspension as much as possible, On my top feed airbrushes I always give the AB a shake or two during the painting process, with my bottom feeds I add a couple BBs to the jar and give them a swirl. My full size guns employ a agitation device.

I don't think Dave is lying when he says he uses 60 psi, it's a common practice when color matching in a collision shop. Have I used it painting models? NO but that doesn't mean it doesn't work.... His results speak for themself.... Excellent work!

I'm sure Dave would agree with me that at that high of pressure you do use more material and create more overspray but again it does works!

I also subscribe to his large nozzle size.... All of my guns have the largest nozzle size I can purchase as you can always throttle the fluid rate down. It's kind of like can you ever have too much Horsepower.....

Based on the information you provided the two big red flags for me were your rate of reduction and nozzle size.

After you address those issues you may be on your way!

Laying down great paint doesn't have to be that difficult and quite frankly isn't. It just takes a bit of time, practice and good overall practices.

Always paint with good lighting, try to maintain a 50% overlap on your passes. Watch as your paint hits the surface and then look at the results, it will tell you the story! faster, slower, closer, farther. It can be a exhausting exercise, however it WILL pay off in the long run. 

I hope this helps.... always here to lend a hand!

Jimmy "RASS"

  

"I Have Flying Monkey's And I'm Not Afraid To Use Them"

  • Member since
    December, 2007
  • From: Portland Oregon: Tree Country. Most beautiful area on the West coast.
Posted by Treehugger Dave on Monday, February 27, 2017 5:44 PM

"Spot on" JW Thumbs Up.

As for using way more paint your right. I compensate by keeping the airbrush back an average of 8 - 14 inches depending on all the variables during spraying. Sometimes a bit closer depending on the subject, graphics and if it's multi-color. I also spray in a heated small area at about 80 - 90 degree's as I live in the Northwest. At that temperature and air pressure it lays down the "purtiest" smooth paint job - Like a babies BU** in my home made  18X30 well lit spray booth with a ventilating "Mega" CFM squirrel cage brushless motor.

On my paints I average about 2 to 1 reduction with my reducers but on my urethane filler primer I usually cut it 3 or 4 to 1 depending on the details and the coverage I want.

As JW said I hope this helps you out.

Glad to have a fellow painter here JW Thumbs Up.

I love Mecum Auctions and Barrett/Jackson auctions and what would I do without Ebay.

 

 

                                     

 

 

  • Member since
    January, 2011
  • From: long island, new york
Posted by chucky on Monday, February 27, 2017 7:49 PM

I have a question for Dave: How do you paint those perfectly simulated reflections of the black and white checkerboard floor on your models?Laugh

Great comments, Jimmy and Dave! Thanks! 

chucky

  • Member since
    August, 2016
  • From: Wisconsin
Posted by jwrass14 on Tuesday, February 28, 2017 2:12 AM

Dave,

It is indeed great to see another painter chime in, My goal is to try to give back to the community as much as I can and it is obvious you share the same view.

I hear you loud and clear about so many paint problems.... I think all modelers should read a 1:1 book on prep and paint and so many problems would be solved..... My Favorite is when someone does a two tone.... I used 12000000 grit paper to get a smooth finish when I taped for my second color and pulled off the tape all the paint came off.... Ya think lol.

Great looking builds....Awesome Paint...... Respect!

EvgO, I predict with help from Dave and Myself (and others) you will be laying down some great paint in short order!!!! I give you a ton of credit for staying with it... Most would have thrown in the towel long ago.... Props!

 

Jimmy "RASS"

 

"I Have Flying Monkey's And I'm Not Afraid To Use Them"

  • Member since
    January, 2017
Posted by EvgO on Tuesday, February 28, 2017 6:13 AM

Good thing about these niche hobby communities is the enthusiasm! 

Thank you guys for chiming in. I'll get back into it as soon as I stop drooling over your models :D

Edit: What nozzle size would you suggest? 0.5mm? 

  • Member since
    August, 2016
  • From: Wisconsin
Posted by jwrass14 on Tuesday, February 28, 2017 8:24 AM

EvgO,

Most ABs come standard with a .03. I have purchased ABs without the standard nozzle and I always go for the largest nozzle I can get for that AB typically it's a .5.

The last 15 years I have used Iwata Airbrushes as I do alot of Automotive Urethanes as they will take the harsh solvents right out of the box. (no upgrade kits)

I have 10 Airbrushes of differnt brands and I can't say anything bad about any of them as the all have their +&- I still have my first AB I got for Christmas in 1963 a Binks Wren

Just recently getting back in to modeling after a 30 absence I don't have any bodies or full builds to show however I will share a wooden Pizza Spatula that I turned into a key ring for my Daughter. It is a Kandy Red over a Rasberry Pearl with Rainbow flake. Art Deco design in muliple types of leaf.... All outlines and lines are done freehand with a brush. As I said you are on your way to incredible finishes like Daves and perhaps something differrent as well!

If you look close at the bottom of the design you can see my Signiture "RASS" in tiny letters.

Peace Jimmy "RASS"

 

 

"I Have Flying Monkey's And I'm Not Afraid To Use Them"

  • Member since
    December, 2007
  • From: Portland Oregon: Tree Country. Most beautiful area on the West coast.
Posted by Treehugger Dave on Tuesday, February 28, 2017 8:36 AM

Beautiful work JW Thumbs Up. Your a true artist. That kind of art work is way beyond me.

I love Mecum Auctions and Barrett/Jackson auctions and what would I do without Ebay.

 

 

                                     

 

 

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