I was funnin’.
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I’m telling personal stories. Anyone can take it or leave it based on their own experience and position in life. All free but refunds are cheerfully made.
I wasn’t disparaging you. I thought it was funny. I liked your story. I’ve recently painted my pickup with brushes and Rustoleum. It took less than a quart. (I primed with the rust-fix primer on the bare spots first.) It had no clearcoat, which I imagine would keep any new paint from sticking, and was worn down from years of desert residence. It looks okay at night - if the moon is new. I hope our stories inspire @grunes_183031 to do it him/her/itself.
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I’d guess the brush painted car would be hard to tell from a spray painted car if you sanded it enough times with progressively finer wetted sandpaper. I know that spray painting is easier, faster, but will the slower and more tedious brush painting method yield similar results with enough sanding & polishing?
One could treat this as a simple physics problem. If the windows were untinted, and perfectly transparent, and everything but the windows on the exterior and in the interior were perfectly reflective white, then the interior of the car obviously would not get hot in the sun - or at least no hotter than the outside ambient temperature.
And if the windows were partially reflective instead of tinted, the interior would be cooler than outside instead of hotter, like staying in the shade.
Unfortunately, those approximations don’t apply. For one thing, I have noticed that on many cars, white vehicles tend to have dark interiors - which tends to defeat the purpose.
Also, car window glass absorbs some ultraviolet and reflect some infrared. Etc. The former, along with tint, means the windows get quite hot in the sun. Combined with dark surfaces in the interior, the latter creates a greenhouse effect.
My VW/Westphalia Vanagon camper was a special case. The interior was almost all white (but not the floor, which had a black mat). It was tinted only at the top of the windshield.
Whereas there are a lot of dark surfaces inside the Venza. Including right next to the front and side windows. If I were good at painting, maybe I could solve some of that.
It makes sense that camper vans might be better designed for some types of weather than most vehicles. If you think about it, many houses in hot climates are painted white, and some have recently been made with light surface roofs, to cut cooling costs.
Venzas are described as crossover SUVs, but that doesn’t mean they are ideal for living in.
No physics needed . Hot summer weather and sunshine make things like vehicles get hot inside. Try setting in city traffic July and August on a motorcycle with a full face helmet on you will not complain about you car again.
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Heh heh. I think if you use like a short nap roller or one of those foam ones it will lay down pretty smooth. I used rust oleum on my trailer but I sprayed it. No offense but I think I was in 6th grade and the guy down the street had a hudson. Don’t know what year but shaped like the hornet. At any rate one day I rode by there on my bike and he was out there painting it black with a brush. I cringed a little bit even then but looked ok at night.
That’s the problem when trying to boil something down with embedded misconceptions. The primary issue is the idea that perfectly reflective white paint is going to mitigate the non-visible (to the human eye) wavelengths of electromagnetic energy from heating surfaces below the paint.
I looked at a picture of a Venza of your model year. The glass surface area appears much larger than the roof area. Painting the roof would be like sticking a thumb into a 3’ foot hole in the dam… Window tints (if allowed) and a windshield sun shade would probably do more to keep the interior from excessively heating up than any re-painting of the roof.
Yes, it can. Put on enough paint and sand it back and the results can be excellent… But the labor is massive. That is why spray painting was developed.
Early Model T Fords were brush painted and rubbed out smooth by hand until about 1924
My great-grandfather used to brush paint his '53 Chevy with laquer every few years. Virtually no brush strokes… his trade was a painter.
One of the museum cars from 1919 was painted with a brush (because that’s how it was done in the day) with linseed oil based paint. It was a very good result but you can see very faint brush strokes. The car was an Indy race car so we know it wasn’t rubbed smooth (even if that was possible with that type of paint)
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Similarly, I did the prep work on my badly-chalked 4 year old '74 Volvo, and then I had an Earl Sheib shop (nicknamed Earl Slob) repaint the car for… I think… $69.95. The paint color that I chose was so similar to the original that it didn’t really matter that the door closure area wasn’t repainted.
Before they went out of business in the late '80s, the price had increased to $99.95.
The sunshade I’m using, though it was nominally supposed to fit my car, leaves the top 8" or so uncovered. And I haven’t figured out a good way to shade the lift gate window. Even the side windows are tilted so a lot of sunlight comes in (the tilt also makes covering them from the inside harder, because a cover would tend to fall off). And all the windows are already tinted.
It isn’t worth putting a lot of money for mods into a car that doesn’t meet my needs well in several other respects, especially destructive mods that reduce resale value.
Some people cover windows with Reflectix when car camping. I could try that, if I can figure out a way to make it stick without drilling. And/Or ignore the theft potential, and use window vents. Perhaps vents that fit in the window channel are marginally more secure than glue-ons…
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I think we were at ft, hood for summer camp and rented one of those gremlins for the weekend. I had my samsonite hard sided suitcase in the back under the hatch window. It got so hot under that window that it warped the suitcase. And we were driving, not parked, so yeah windows.
The odd thing is that all that window area doesn’t give the vehicle good visibility - tilted windows, streamlined shape, a long hood, and obstructions, all interfere.
I wonder if streamlined shapes actually make sense from a gas mileage perspective. To get the same interior space volume, you need a longer or wider vehicle. My 1994 4WD Ford Ranger had more interior space (with a camper shell), and got marginally better MPG, and my late 1980s or early 1990s VW Vanagon camper (admittedly not 4WD or AWD), with much more interior space, did almost as well, despite older engine designs. (And both stayed much cooler, as far as I can remember.)
Are streamlined shapes more for looks than for gas mileage? (It is true that my Ranger MPG went up after I added the shell, so maybe streamlining helps a little?)
Well of course it does ? Why do you even have to ask ?
I remember reading a long time ago that at the speeds that cars move, streamlining is largely irrelevant. That was before modifications in engines & drivetrains made cars more efficient - maybe it matters more now.
But a pickup truck with no cap may be an extreme case of poor streamlining. It is still a legitimate question whether the somewhat streamlined appearance of cars like the Venza (let alone sports cars) actually improves gas mileage, for a vehicle with a given interior volume, or whether one would be better off making the vehicle a little more boxy.
But that is off my original topic.
Maybe I was thinking about this all wrong. Maybe one could choose wideband optical properties of interior and exterior surfaces, as well as window shapes and passive ventilation properties, so as to minimize solar heating.
But that might not be desirable. Maybe the main engineering goal is to reduce moisture and mold. They wanted to let the heat bake out interior dew and frost.
In addition, maybe some ultraviolet is allowed through to help kill off any mold that forms. Plus - it is already the case that adaptive sunglasses (e.g., Photogrey) don’t work very well in cars, because windshields block some of the UV to which they respond. They would work even worse if windshields blocked all of the UV.
EDIT: I should have said “a major engineering goal” instead of “the main engineering goal”.
And of course maybe the tradeoffs on mold prevention vs excessive passive heating might differ according to climate and weather.
But, whereas the climatic influences on choosing 4WD & AWD, or convertible vs sedan, might be obvious to many, how hot a vehicle gets in the sun is less obvious. And It isn’t something that common car review sites mention. And it would be hard for most people to figure out which vehicles get the least hot in the sun. It certainly isn’t something that a car sales person has mentioned to me.
Ah wrong. Wind resistance is EXTREMELY important and very relevant. Companys spend MILLIONS AND MILLIONS every year streamlining their vehicles to meet the Cafe numbers. Around 50% of the vehicles energy at higher speeds is fighting wind resistance.
Air Resistance: The Invisible Enemy in Vehicle Design | SimScale
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Most people know that a lighter shade of paint will not be as hot as a darker color. Just like house shingles that are dark will make the house hotter that the lighter shade does . You making this way too complicated . And seriously , do you think that a car sales person is going to say " You don’t want that car because it will get hotter than this one " ?? Not a chance.
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If it was irrelevant, Kenworth wouldn’t have spent 6 years and a lot of money in order to develop their new Super Truck 2:
From the company’s website: The unique look of the Kenworth catches most of the attention, but the powertrain and driver amenities are just as impressive. “We started with an ideal aerodynamic shape when we started the design of SuperTruck 2,” said Joe Adams, Kenworth’s chief engineer. “At the start of the project, we asked ourselves, ‘What does the next generation vehicle for long haul transportation look like?’ What we produced pushes the limits in reducing aerodynamic drag while it also incorporates a new powertrain.
This pic shows their progression in aerodynamic improvement over previous designs.
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That’s been answered many decades ago. Drag is a square function of speed. Go twice as fast and the drag quadruples…just stick your hand out the window at 65 mph. Place it horizontal and then vertical to the wind. Does surface area and the angle matter?
Think about it. If you let even more energy into the car interior, do you think the heating will go up or down?
Car windows are made of float glass- a type of fused silica glass that passes UV down to around 250 nm FWHM. To go lower, you’d need sapphire or MgF2 glass and it should go without saying, that is economically unfeasible. Besides, increase the short wavelengths penetrating the interior will significantly increase the interior heating as the energy heats up the materials inside and re-radiates longer wavelength IR.
The major engineering goals are; pass visible light and block as much energy outside of that as economically feasible. They don’t want to create more heat to manage because customers demand fast cooling. That increases the burden on the cooling system and costs more money to provide. Float glass is the cheapest option that meets the goals. A borosilicate glass would block more UV but again, that is cost prohibitive.
Moisture buildup and mold are a customer problem to deal with.
Not going to happen. You need direct radiation for UV to kill any organism - and lots of it. I’ve had many dealings in UV sterilization over the years going back to before the Anthrax scares, to medical applications for wound sterilization to the more recent Corona virus concerns. The wavelength and dwell time are very organism dependent but typically 222nm is most generally effective. Float glass blocks those wavelengths. And, you need a boatload of photons in that energy range to kill mold. Finally, most of the car interior is not subjected to direct sunlight.
EDIT: forgot to mention, the shorter wavelengths will also color bleach the interior and break down plastics faster so that is another reason manufacturers do not want short wavelength UV penetrating the interior…
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Me thinks your memory is wrong.