Spray Paint Finish Process: ????????? Surface technique for Prototypes Models & Mock ups

my name is Eric Strebel I’m an Industrial
Designer welcome to my channel about product design and making I hope that
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bundle basics video I built the cell phone holder that I designed in this
video we’re gonna take a look at how to finish and paint that thing so you get a
fantastic finish for your mock-up we’re gonna start with a good quality
automotive primer I’m using a dupli-color primer that I got from the
automotive supply store do not use rust-oleum again don’t ever use
rust-oleum you’ve been warned once we lay down the primer and it dries after a
few coats we’re gonna go in here and we’re gonna fill in any little pinholes
and imperfections that we can find we mark them with a pencil we’re gonna go
move to our spot putty I want to put this on with a little rubber squeegee
we’re gonna end up standing off about 90% of all the spot putty we put on
you’re gonna see here shortly if you’ve ever watched any of my previous videos
you know the rule sanding always use a sanding block always so we’re always
using a sanding block here I have some different ones you may make need to make
special little sanding blocks I use a foam roller pad here I make them out of
pink insulation foam a piece of cork anything that’s flat something that’s
nice and form-fitting here I’m using a wooden stick that I have a piece of
sandpaper wrapped around so I can get nice and tight on those inside surfaces most of the spot putty gets sanded off
we’re coming back with some nice light coats of primer I’m just lightly hitting
the surfaces building up the primer we have a few more imperfections to fill
here and we’re gonna do this a few more times back and forth filling them every
time with the spot putty until eventually there are none left all right
we’re gonna get back on it with a sanding block of course this keeps the
surface is nice and flat and it’s how you get quality a glass surface you
can’t do it with your fingers it’ll never work here I’m using a round piece
of PVC with my 220 wrapped around it and that’s what I’m starting these first
layers with I have a little piece of bondo that chipped off so I take a
little bit of glazing putty and I make a new little corner I make sure to remove
the primer from the bondo because the bondo will not stick to the primer very
well you’ve been warned I trim everything off in its rubbery state with
a nice exacto blade and we’re back for the next round of primer when you’re
spraying your primer you’re laying down thin light coats you’re trying to build
up the primer not too heavy you’re only pressing the button as you
approach the object you let it go as you exit you’re not pressing the button the
entire time like a cartoon character don’t be an amateur we’re gonna do a little bondo squeeze
something that we learned in the advanced bondo video I’m putting on a
little bit of polyester filler here onto a round dowel PVC and we’re gonna put it
into the side indent of the cellphone charger and this is gonna give us a nice
form and we’re gonna use that to help us sand out and get a really nice surface
so it’s certainly a lot easier to sand a convex shape than it is to sand a
concave shape thus the little bondo squeeze want to put on a little bit of
sandpaper that we’re going to spray mount onto it I’m using probably a 220
grit something like that and I’m just gonna rotate that in the concave space
of the cellphone holder and that’s gonna give us a really nice finished surface
there we’re gonna lay in some more primer here again you’re only spraying
paint when you can is parallel to the surface that you’re painting few light
coats and we’re back to sanding again using a sanding block of course at this
point I’ve probably switched to a 320 grit sandpaper 400 it seems as I’m
starting to get a smoother and smoother finish every time as those imperfections
pinholes and things are starting to disappear we’re back for another coat of
primer again light coat so I get good surface and I don’t get
too much bill now that I’m pretty much done sanding
and priming the last coat I’m gonna do in white and this is gonna give me a
lighter color surface it’s also a great time to test out your paint and this is
the raspberry color paint that I’m using I am testing it out on different sub
surfaces and I also happen to notice that this can spits a little bit so I’m
gonna make sure that I have a little bit of solvent to clean the nozzle so that
when I go to lay my final paint down I don’t have any issues you’ll notice the
tones on the right are a little bit darker because they have a dark
substrate so that’s one of the reasons I’m going with a white substrate and my
final coat of primer is white so I get the color that I really want it’s subtle
but for me as a designer that’s super important this last coat of white primer
I’m very lightly sanding it of course with a sanding block and 600 grit
wet/dry sandpaper is just to knock off any of the little surface roughness that
may have occurred to get the surface really nice and baby smooth so at this
point you have what’s called a white model a perfectly primed part that’s
ready for paint so I applied again light coats of my paint here I’m using a
Montana raspberry very light coats I am building up the color as I go I’m doing
the bottom first and you’ll notice I had a hole in there before I want to flip
the card around again light little coats I’m only spraying when the can is
parallel to the parts let’s go ahead and flip the part over
I’m gonna use my sixteenth inch piece of piano wire here that I’m gonna insert
into the bottom of the cell phone holder I have that little hole specially there
for that I put it on to my round turntable now I can paint the entire
object with nice light coats of uniform color I’m gonna build these up the first
few layers are pretty light I just want to get a base coat down I’m gonna come
back with a second coat afterwards and give that whole thing a final uniform
finish right here remember when in doubt read the instructions on the can but
nice light coats parallel to the surface of the object that you’re painting it’s
going to give you a fantastic finish at this point you could put any kind of top
coat finish you wanted on if you want a glossy or a soft touch I’m just gonna
leave it natural paint don’t forget to subscribe to my youtube channel I can
click on the little icon on the bottom right out of the screen to do that you
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other design and making videos that I have if you’d like to have your music
features in one of my videos drop me alive


  • Bassam Bassam


  • Oliver Bailey

    finally someone that knows how to spray paint properly

  • Chris Brent

    I love that you have an, "Always use a sanding block." rule! I drives me crazy when I see people sanding with their fingers!!!! Have you tried primer filler for one of the final coats? It's kind of thick primer, useful for getting the large pin holes.

  • Michał Regulski


  • Karl Lautman

    What's wrong with Rustoleum automotive primer? Do you like Dupli-Color for color, too, or just primer? If the latter, what do you like for color?

  • Jim at MidOhio

    Very nice – did you ever license this product? Thanks for the video!

  • Marco Costantini

    Great design. Loved the video.

  • GeorgeGraves

    Great series! I hope you don't think I'm being "that guy" – as this is an honest question. But I couldn't help but to notice there was several flaws and imperfections in the final shots. I assume that you were just using this as an example of how to prep and paint, and that it wasn't 100% perfect "show-room" part? Am I correct in thinking that?

  • Mr. Fox


  • Studio Niza

    That was great. Thanks for sharing your step by step

  • Jerome Demers

    wow great tips and tricks. I occasionally do some stuff like that at work but I did not know your technic @4min on the bondo squeeze! Thanks!

  • George

    Thanks, very informative video, but what about the bottom (holder for painting) hole? How will be the over all painting even if You fill it at the end and paint just that part?

  • Sebastian W.

    Hello Eric,

    thank you for your video. It's obvious that you attach great importance to perfection. The result is impressive. I am as well trying to get the most out of my current project. Let's see how it will be :).

    At the moment I read through many tips for my current project and already have the paint, filler, etc. together. Now you're relying on primer, though. Of course I did not buy explicit plastic primer. Only classic rust protection primer and spray filler. Will this work just as well?
    Since the device should be used at the end it would not be so nice if the paint peels off at some time.

    In my first test, the paints stick together and are relatively scratch-resistant to plastic and fingernails.
    I have the following products:
    Rust Protection Primer – https://www.motipdupli.com/en/INT/lang/products/dupli-color/mobility/cars-rallye-sprays/ipg-1090.html
    Filler – https://www.motipdupli.com/en/products/dupli-color/mobility/preliminary-treatment/ipg-1002.html
    Black Paint – https://www.motipdupli.com/en/products/dupli-color/mobility/cars-rallye-sprays/ipg-1089.html
    Clear Lacquer – https://www.motipdupli.com/en/products/dupli-color/mobility/cars-rallye-sprays/ipg-1088.html

    And thank you pretty much for the tip with the sanding cork. I will print special shapes out of TPU, which will have exactly the right radii and shape. Especially with the concave shapes on the buttons I will need them.

    BTW: Nice trick with the plastic foil underneath the filler cap 😀

    My current Project:

  • Matthew George

    Great video! Which spray paint brand do you prefer?

  • Mack the Maker

    I'm absolutely loving your channel! All the videos I've seen (slowly working through them) have been super informative. Thank you!

  • cjs33139

    LOVE your videos Eric. Wish I had seen them when I was in Design School!! Though I appreciate your technique and appreciate the dedication to perfection, I am SO glad that at my company, we have paint technicians that paint our models for us (with some occasional guidance from us designers); because my job is hard as it is sketching/ideating, CAD, foam core mockups, etc!! 🙂 Thanks for the videos, Eric!!

  • John Robinson

    "Don't be an amateur." I love that. Most of us ARE amateurs, of course, but we can attain the mindset of a pro if we are careful and meticulous.

  • XXXJerry Espino

    Does this work on yellow foam? I am a student , please link the good car primers haha

  • Lance Sytat

    Hello! I’m an industrial design student from the philippines and my weakness is 3d modelling or doing mock ups! I apperciate all your videos and keep it up! You’re my inspiration so i wanna thank you and happy holidays!:)

    What material did you use to start your model before the priming and all thank you and i apperciate it!:)


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