- Hey, YouTube viewers.
This is Donnie Smith and welcome to this video series
that is designed to help you pass the A.S.E exam.
Now, this video series is specifically
for the paint refinish.
And, what we’re gonna do is we'll go through the task
and give you the knowledge to pass the test.
What this is not,
this is not really your prep test-type book.
You know, it not just test questions.
If you want that,
there is a link down the, in the description.
You can get more information about that.
What this is, this basically goes through
all the tasks that you will need to know to pass the test.
(tires screeching)
(metal crashing)
The next task that we’re gonna look at
is to strip paint to bare substrate.
Basically, removing the paint.
Now, first of all, before we move forward,
I wanna talk about what is the substrate.
I have the habit of saying, strip to metal,
but you know a lot of the parts are not metal.
They may be a plastic.
They may be S.M.C, sheet-molded compound.
They may be aluminum.
They may be fiberglass.
A wide variety of materials are used to make these cars.
So, the substrate just means to strip down
to whatever that surface is,
whatever that material is.
Now, I just wanted to touch on that,
just to make sure that we wasn’t confused
about the substrate before we move forward.
Now we touched on this in the last video,
but I want to dive in a little bit deeper,
talk about some of the paint defects
that may cause us to have to strip to the substrate.
Now, the first most obvious cause
is gonna be adhesion failure.
This is where you’re gonna see the paint
it’s gonna be peeling or flaking off of the surface,
off the substrate.
And this is due to a lack of adhesion.
For whatever reason, this could be from the factory.
There’s a lot of cars from the factory
that have paint defects where the paint has lost adhesion
and it starts peeling off.
Or it could be, you know, due to the last paint job
wasn’t prepped properly or whatever the reason is.
If it’s peeling off or flaking off,
that’s probably gonna require
that you have to strip this down to the substrate.
Another problem that you may see
that may require you to strip the car down to the substrate
is if you look at the paint surface
and you see any bubbling.
If you see bubbling, that could indicate
that there’s rust, surface rust
under there starting to form.
And that may require you to have to remove the coatings.
Or, if you do see some rust,
some rust that has broke through the paint,
that may require that you have to strip the surface
down to the substrate.
Another problem that may be a little bit harder to identify,
but, if you see that it’s real dull,
a panel’s real dull, it’s lost all of its gloss,
that could be oxidation
or it could be just faded or whatever,
but it could also mean
that there's tiny little cracks in there
and you can’t really see it if you just glance at it.
You have to look at it really close.
But what it is, it’s checking or it’s like a micro-cracking,
just really small cracks and if you look at really close,
you might even have to use magnifying glasses
that they have that have the little light in it
and you look down on the surface.
If you look really close, you can probably see it
and you’ll see those small little cracks
in the paint surface.
Now, if it’s doing that, that’s gonna require
that you strip those coatings down
to the substrate as well.
So if you see something that has lost its gloss,
be certain to look real close at it
and determine if it’s just faded oxidizing
or if it’s checking or micro-cracking.
Now another problem you may have is someone keyed it
or someone put a scratch in it or whatever.
It has a scratch and there may not be any dents there
but the scratch may go down to the metal.
And if that occurs, you are gonna have to strip,
you may not have to strip the whole panel
or the whole car or whatever it is you’re working on,
but you may have to strip that area down to the substrate.
Now, you can probably go ahead
and feather-edge on either side of it,
but in that area, you want to be sure
that you strip it down.
Another reason, kinda similar, is rock chips.
A lot of times the rock chips will go down
to the substrate surface.
This comes, you know, you’re following vehicles
and the truck's throwing rocks up.
You may only find these, a lot of these rock chips
on the front section of a car,
on the nose or front bumper cover,
hood, things like that.
And, basically, those rocks hit
and knock the paint coating off in that area
and sometimes it’s down to metal
and sometimes that’ll also cause surface rust.
So, you know, if you see that
and notice that there's a lot of chips
and it is down in the metal surface,
probably gonna have to strip that down
to the substrate in that area too.
Now, again, this is probably the one
that you can strip the areas
that need to be down to the substrate and then feather in.
You’re not necessarily gonna have to strip
the whole car down because there are
some rock chips in the front.
And the last things we’re gonna talk about in this video
is your paint mil thickness.
And, if you notice that the paint mil thickness
is 10, 12, 14 mils thick or more,
that’s gonna require you to strip it down
partially or completely.
Now, this is probably gonna be preference,
how your shop or how you prefer to do it.
If you would rather media blast it
or just D.A. sand to partially strip some of it off,
that’s gonna be your call as a technician
or as a shop owner.
So, if the paint mil thickness is that thick,
you’re gonna have to do something though.
On your edges, you know, you keep building up
and it makes your edges smaller and smaller
as you put coatings on there,
and that’s gonna make your gaps too narrow
and you open the door, they’re gonna hit, rub,
knock paint off and it could also lead
to adhesion failure down the road.
I mean, there’s a lot of problems that can lead to,
so if it is
10, 12, 14 mils,
you may consider partial or full strip.
Now we've talked about some of the paint defects
that may result in having to strip it to the substrate.
Now let’s talk about a few techniques
to strip the car down to the substrate.
So we basically got three methods to remove paint coatings.
And, there are some other ones we’ll talk about as well.
The first one is chemical stripping
and this is where you use chemical strippers
and that eats into the paint.
That was used a lot.
It’s being used less due to EPA
and being compliant and things like that.
But, you know, if your shop is allowed use that still,
then that may be a method that you can use.
And the second one is media blasting.
Now, they used to use a lot of sand with the thicker metals.
These thinner ones you have to be careful.
They got different materials you can use for that.
And that’s where you use a blaster
and you actually blast the coatings off.
And the third one is sanding.
And we talked about this in the last video,
but that’s where you use a sander
to sand down the paint coatings.
This could work well for your partial,
if you’re just taking the mils down,
or you can go completely to the substrate
using a D.A. sander
with 36 or 80 grit.
Now there are a few other methods that I have used
to remove paint coatings and this works especially well
if you have adhesion failure for whatever reason,
you know, peeling, flaking, or delamination or whatever.
One of them is to use a high pressure washer.
You hit it with that, sometimes that'll take
a lot of that coating off for you.
The second one is use a air hose.
Same principle, doesn’t work quite as well,
but sometimes that will take a lot of the paint,
the paint that wasn’t adhering well, adhering properly,
it'll remove that.
And the third one is a razor blade,
where you basically, and you have to be careful
'cause this will cut down into the substrate,
but if you carefully take a razor blade,
and the paint’s not sticking well,
you can basically just scrape the paint off.
You have to be careful.
Those are a few alternative methods that I’ve used.
They seem to work well for the right application.
If it's especially adhesion failure
where you can take that paint off real easy.
It is my goal to keep these videos short,
so that’s all we’re gonna cover in this video.
Just give you little chunks at a time,
let you absorb that and then you can watch the next video.
Down below is a link to the test prep books that I have.
But also there’s a link that'll take you
to all these videos if you're wanting
to go through more than one video at a time
and take you through the entire playlist.
Be sure and check that out
to go through the ones that I’ve already uploaded
and as they become available,
they’ll also be put on this site as well.
Thanks for watching this video.
I hope this helps and good luck with your A.S.E. exam.