That's the debate right there. There are positive pressure and negative pressure booths. There are pros and cons to either way.

The main reason you want a booth to be positive pressure is to avoid sucking in any particulate from bad seals. If you have great seals, and you're confident, you can do either way and not take any risks.

The main reason you want something in between would be to push air over the spray surface, so slight positive pressure.

The main reason you want negative is if you can move air faster out of the booth than into the booth, which also achieves the above result, depending on air velocity.

As this is an amateur operation, we chose positive pressure so it would keep it clean, and it's working great for that.

You can't put box fans as exit fans with automotive paints because the fumes can spark and create an explosion. However, you can build a baffle (out of cardboard) that would "catch" enough of it that makes it safer. Though once you start having to mess with all that, it makes me think you ought to build something that's better than pvc and plastic tarps.

A couple thin coats of Omni MC760 clear.

Note, we're not going for a gloss look, this is just a intermediary step. When we're done, we'll use a matte clear as the final coat. This clear is to set the speckle and surfaces that will be getting stencils. Everything cleared here will get sanded with 800 grit and cleaned prior to stencils or final coats. If we sanded without the clear, we would risk sanding off the speckle or cutting too deep into the base color.

It would be nice if we could do this step with matte clear as well, but unfortunately the matte additive, when sanded, will cloud up and mess up the colors. You can't sand matte-adjusted clear. So, a few glossy shots before the next step, sanding and stenciling.

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Our home is a little weird in that the pollen is so over the top, if you wash your car, twenty minutes later you get a fine yellow dust on it. I did the last restoration in the driveway and it was ok, but we needed an upgrade.

Ok, here's some more interesting things we learned.

You may recall that we chose to follow the High_End_Pins method and shoot a intermediary gloss clear over the base coat and speckling.

I completely get why he does this now.

The speckle, once it dries on the base coat, literally feel like bugs stuck in the paint. The drops are sometimes pretty flat, but often are not. I don't think it matters how they are applied (via a under-pressured HVLP or with the toothbrush), this is the case.

If you were to sand those flat, you'll end up just pulling most of it off and losing that work.

Instead, we shot base coat, speckle, then a couple coats of gloss clear.

Next, we sanded with 800 grit (this is debated, I've head everything from 320 to 1000, YMMV). This took the surface to a glass smooth level. Now it's in much better shape to receive stencils and keep straight lines/prevent bleeding on the next step.

This being said, imagine our surprise to see this:

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If you look closely, you'll see that after hitting it with 800, and believe me it's smooth to the touch, you can see some gloss clear getting left behind precisely along the original grain. Mind you, you could not see any of these grains/lines before the sanding!

I'm sure it's fine, after doing coats of stenciled colors followed by a matte clear coat, this shouldn't be visible. Still, is this weird? At first we thought it might be orange peel being left behind, but that's clearly following the grain. Interesting, right?

I agree with your sentiment, Yves. As this is a restoration, our goal is to get the machine to what it may have looked like new, if not a little better. Even the cabinet, as it arrived, was smooth to the touch and not showing grain, so I wouldn't try to do much more than that. The purpose of this step is not to create a glossy, glass-like surface for the final product. It's to help with stenciling.

This layer of clear is unaltered gloss but is there only to set the speckles so they don't get lifted with the stencils. We can't shoot matte clear because it doesn't take well to being sanded (creates a cloudy base once sanded). However, once this is done, we will shoot the whole surface with a matte clear to make the gloss level consistently matte. You won't even be able to tell it's been clear coated. So yes, this is purely for stenciling...and also to help get the surface similar to how it looked/felt before.

We went through a lot of work to get the cabinet masked in preparation for applying the stencils. Unfortunately, we were using yellow (low adhesion) frog tape, and it just started coming up after a certain point.

I like the yellow because it leaves zero residue, but clearly it's not good for holding paper to a surface very long.

3M makes their various types of Scotch Blue tapes, we're probably going to re-do the whole preparation using yellow Frog for something with a sharp line (like a corner), and the blue for holding masking paper. Any tips/wisdom?

Thanks... that's the key, the good stuff. I think that is the Scotch I have successfully used in the past. I'm guessing it's closer to green FrogTape. The yellow is my problem: Probably great for very low tac applications (maybe playfield?) but won't stay stuck long enough for my needs.

Cabinets masked in anticipation of stencils. Stencils that are against edges will get "married" to the tape prior to painting.

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In this case we've moved to FrogTape green (medium adhesion) for anything taped to the paint. For tape to tape or tape to paper we're using 3M green, which is high adhesion. I'm much happier with this.

Prepping stencils. This involves trimming them. First, we make sure the stencil fits properly...this is mostly for the head/backbox because these early Bally's have a raised edge along the front.

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We use a straight edge and a new blade to cut into this. We've triple checked to make sure we're not hitting any artwork (and we're leaving necessary registration marks exposed).

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We're cross referencing photography. There's a certain amount of restorer's license going on here, deciding what edge to favor and what looks best. For the cabinet sides, we opted to favor the bottom edge, so that the artwork gets pushed up above the lower line of the rails. We noticed that when we removed the rails, there was less than 1/4" of overlap (if you zoom in, you can see the unfaded strip of pink), and that was awfully close...It would be horrible if we finished this and the rails didn't properly overlap the artwork! Instead, we're going for the lower details and pushing art upwards.

A reminder, this is the original:

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I find it interesting that the stencils leave a white area for under the rails. You're just inviting a mistake there, I think.

Ok, next step, we apply the stencils. We're waiting until the morning of painting because we don't know how long these stencils like to be adhered and don't want to take any chances.

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Ok, next step, applying these guys!

Perhaps, they seem to do the basic job of keeping dust from coming in during the painting and keeping paint inside. I'll make sure they have enough air flow before jumping in.

Do you feel this will work well with automotive paints? I had a really rough time fixing mistakes during the speckling. Also, what type of stencils did you use?

I use mineral spirits, though lacquer thinner also cleans it up quickly.

Our biggest fear is the timing. Automotive paints set really quickly and are dry within ten minutes. For this reason, we will set up all the stencils for one color. We'll hit the entire head and cab for 2 to 3 coats, then immediately remove the stencils. Stressful.

A great many things learned today!

First, we applied stencils.

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Where stencil material met an edge (where there was no painting), we made sure to extend into the mask:

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Ultimately, I have to agree with all of you, Pinball Pimp's stencils here applied fantastic. We took some tips from others, and covered the "X" registration marks with masking, so our opaque paint wouldn't obscure it.

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All stencils applied and ready to go:

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We used Delfleet Essential automotive paint. This is a 6 to 1 to 1 mix ratio and dries solid in about 30-40 minutes. My mistake, the other automotive paint I used for the base was Omni MBX, which dries much faster. At a high level, the stencils worked great and fairly happy with the results:

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There were some great outcomes:

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...and some HORRIBLE outcomes. You can't imagine how upset this made me... it was 100% my fault, I forgot to adjust the pressure on the first spray (yes, I tested it first, but failed to pay close enough attention). We'll have to sand this out.

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In terms of when to remove the stencils, because we thought this was going to dry in 5-10 minutes, we began removing the stencils off one side of the cabinet really quickly (15 minutes) after application. we quickly realized this was a mistake. The paint was extremely sticky, and would sometimes stretch or string. It still kept the edges and lines as we wanted, but those lines are far rougher/more raised.

In contrast, we started the second side of the cabinet about 1 hour after application. All the lines were clean and no lifting or stretching. For paints like this, I recommend waiting for the initial cure time before removing, not when wet or sticky. Because the base coat was cleared and solid, there was no base lifting either, though the material from Pinball Pimp seemed unlikely to do that.

By the time we got to the head, the paint felt like the surface of a car, and yet it still came off cleanly. We used a pair of tweezers and an Xacto knife to get to the pieces.

As for those paint runs, I'm hoping I can just sand them down before the next stencil layer. Once the next stencil is finished, we'll do any touchups...and depending on how ambitious we are, we'll probably do some regular clear to level out the lines, sand, and do a matte clear to finish it off.

Sanded out the runs. This stuff sands out fine. I'm using this Delfleet Essential only because it was the only paint manufactured that made the color close to what I want.

It turns out that DuPont made these crazy colors (like the original Future Spa) back in the 70's, and stopped for some reason (I'm guessing it wasn't particularly good for you). To match bright neons, you're better off with things like Createx Airbrush colors vs. automotive paint. Still, we got what we wanted.

It's called Delfleet because it's targeting fleet painting, meaning a lot of cars in a short amount of time. It's a base and clear, so it dries super glossy. If you sand it, it's because you know you're going to clear over it. We can hit it with naptha and tell it's retained its color.

Another thing I learned today: Another good reason to shoot a coat of clearcoat after a stencil layer is for sanding purposes. If you sand around the edges, and it's high contrast (say, pink and bright white), the pink dust can grind in a bit to the top layer of the white. It cleans off with naptha and a little elbow grease, but you can see how having a layer of clear in there would avoid sanding actual color and achieve similar results.

We couldn't do that because we were fixing the runs. When we were done, we hit all the cab with 800 to knock the edges down a bit in anticipation of the stencils. We're nervous that the paint edges are so high that we may see some bleed through the stencil material.

Stencils ready, prepped for purple. It's about 58℉ outside this afternoon so we'll just have to wait for warmer weather or we'll get more runs.

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I've got to say, these Pinball Pimp stencils are pretty impressive. I don't see any way around enhancing them a bit by adding some masking tape to extend the stencils over the bevel. Otherwise, you would end up with a colored outline around the edge, and we didn't get this far by letting that happen.

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Does anyone know if you can do touch ups with automotive paint without the HVLP, maybe with a traditional airbrush? We're happy to mask and shoot touch ups, though the clean up is the same as if you're doing a large area and quite a pain.

Maybe a finer point on the question: If I shoot automotive paint with the HVLP, and switch to a small airbrush for touch up, will it blend properly? As long the the atomization via the HVLP doesn't actually create a different color.

We're actually pretty happy right now.

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There's something about planning stuff out, executing, and getting it right that just makes father's day 100% perfect. The lighting doesn't do it justice. We hit the red with 800, so it's been deglossed, and the purple was still curing in the photos...and the lighting was weird. But we're happy.

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Next stage is mixing touch up paint, fixing any little mistakes, and then move to do some coats of regular clear, sand, and final matte clear.

Unaltered coat of MC760 clear to lock down the colors. This is not the final surface as we will finish with a matte clear. Our intent is to sand this flatter, see how it looks, and decide if it needs another coat of clear and sanding prior to final topcoat.

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I should add that we don't really think this needs to be perfectly flat. Stencils have layers. Original machines had those layers as well. Even as a resto-mod, we would be fine with some edges/layers. However, if you ever choose to use automotive paints, I recommend two stage, basecoat paints. The colors we wanted were unavailable outside of the single stage paint we had access to, and unfortunately those have clear built into them and tend to go on a bit thicker. You can convert them to two stage, but they remain pretty thick.

Compare this to a rattle can, where really it's simple and what you see is what you get. This automotive finish is amazing looking, like a car, and we really love how it looks...but it has its drawbacks. The challenge next is block sanding it without cutting into the color in a damaging way.

Taking some time trying to match the dark red paint of the apron to fix up some damage.

We're using Createx airbrush paints for this.

This is where experience counts...and we have none. I've managed to make a nice purply brown.

Anyone have any advice for this? We've followed @vid1900's method but for crying out loud, it's super frustrating!

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We start with red, add a little yellow...seems to be going in the right direction, but too bright. If we add blue or black, things go off the rails really fast.

Yeah, I appreciate the alternatives... We're committed to restoring this one. It's literally almost perfect, having come from a NOS assembly. It's just a matter of matching a small amount of paint. There are literally no ball trails, it seems to have been scuffed either in transit or during its brief life in a HUO condition.

We're going to try both our match (by eye) and professional match (computer + professional eyes) and see who comes in closest. The challenge with the pro match is that it's latex, but that's fine, we'll thin and airbrush it.

Funny, I just got a call from the professional paint matcher. He says that the color is an usual red, and very difficult to match. It's not just me! He's going to try some oil-based alternatives just to see, but you can imagine that I'm not thrilled.

We may have no choice but to sand it all down and restore everything with waterslide decals on top of a new red. Disappointing. vid1900 any sage advice here?

Ok, first round of clear has been sanded as flat as it would go until it started to cut into the color (as expected). Minor touch ups completed, and another round of clear shot. It went on pretty smooth this time. After it cures a few days we'll sand again and hit it with the final, matte clear.

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Nothing like a real professional willing to do a little extra homework. We have our apron red!

The short version is that with water-based paints, it's extremely difficult (if not impossible) to get this Bally red without crossing over into muddy or brown. It has to do with the red pigment and modern chemical regulations making it difficult to pull off.

I got a very experienced professional to figure this out, and he started with a very expensive (like $50 expensive) quart of European Hollandlac oil-based enamel. He spent the better part of two days adjusting, and was able to hit a color match by adding a violet purple and another purple to the mix on a satin sheen version of the paint. After performing the naptha test it's pretty much dead on.

Unfortunately, since this is oil based and everything else we're doing is not, we have to be very careful using it and ensure it cures fully and then scuffed properly before clearing over it (which is absolutely required since it has a different sheen than the rest of the paint we're using).

For future reference, this Bally red was achieved with Hollandlac Satin 1002 Rembrandt Red, with ALK24-1Y and ALK241-4 added, by eye.

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The slightest scratch with an Xacto knife on the apron creates a trail of lifted paint. Note to self: Just say no to cutting Frisket until I have more practice.

Added new coin door guides. One of the originals was completely missing, the other was a science experiment of 40 year old beer goo. The new ones are bit sharper than the originals but we like them this way:

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Then, re-taped for matte clear application. Next, we sanded with 600 for final application of clear coat (matte/eggshell level finish):

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Next step is clear coating the apron and shooting that final matte clear. The temperature is around 76 degrees out so we're waiting for the temperature to drop to around 68 or so before shooting.

Apron cleared. Not perfect, but a real improvement.

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Yep, that's the plan. It's only on the edges the player can't see anyway. We got some orange peel above the repair in the upper left, I think mostly because it's on top of oil paint (which wasn't supposed to work at all).

I can't stress enough the importance of temperature on clear coating for us. In the end, we found that 68 degrees was the ideal temperature and the clear would "flow out" into a perfectly flat surface.

The challenge, though, is runs. Clearing the final coat on the cabinet went perfect, but the back box had runs on one side, so we'll need to sand that out and recoat. Almost there.

Thanks! As we repair these runs, we'll put the backbox horizontal. Unfortunately, given the way/timing and pot life of the clear (about 2 hours before it's unusable), we couldn't figure out a way to do one side at a time without wasting a ton of clear...maybe we should have just done it one side at a time. Too late now. I have been watching others do it vertically, and you're right, the artisan experience counts here. Watching @high_end_pins do this without any fear is amazing. That's what an accomplished automotive painter brings to the table with this!