Large photo printing and mounting ?
 

I have this idea of grabbing a couple of vintage Porsche pictures I have, blowing them up 4x6 Feet, and mounting them in the garage... Dealership style ;-)

No frame, just glued to a foam backing or something, and hopefully somewhat resistant to a non A/C garage.. Any suggestions on who could do that (online photo printers?), or a specific material I should use to avoid humidity damage?

I recommend white house custom color whcc.com

There are a ton of materials that can be used.

But material will affect how it prints. You would want a heavyweight coated stock or mylar for vibrant colors.

Then there is the ink factor. A lot of the inks are vegetable/water based and are not meant for outdoor use or areas that get sun/light exposure, they fade rather quickly.

Mounting certain materials can also be a hassle. The less fiber in the product the harder it is to get it to adhere to substrates. The adhesive can't soak into the pores and over time it simply fails.

I'd get it done locally. Expect to pay ~$10-12 per sq ft for the print, mounting is additional.

I should have added: B&W ! No color involved, all greys ;-)

I might not recommend that.

There is a difference between b/w photos and b/w prints.

Black is not a color but in the print world black ink is required. In theory 100% magenta, cyan and yellow will equal 100% black. In reality it comes out to a very dark nearly black brown. Black ink is used to make it look correct.

Black ink on it's own tends to be flat, dull. When we can we add 10-15% cyan to it to make it appear richer.

Without seeing what you have and without knowing what equipment/inks/materials will be used it's hard to say if it will meet or fail to meet your expectations.

Then look into getting it done on metallic paper. B&W looks great on metallic paper.

This guy does work for major stores.

Evolve Imaging - Digital Printing

we do our large prints on textured canvas with wood frame either visible or not. texturized isn't visible until u get wthin about 3ft distance

Personalized Photo Canvas Print - 24" x 36" Framed Canvas Art.

That is true for older technology printers. The 60 inch wide printer we use has "Light Light Black, Light Black, Photo Black & Matte Black inks as well as Light Cyan, Light Magenta, regular Magenta & Cyan & finally Yellow. It makes knock your socks off B&W prints and it better than anything I ever saw from a darkroom in the 30 years I worked in professional photography.

The prints that come off the printer are water proof and are supposed to last 100 years in normal lighting conditions. That is way longer than any silver halide color photograph will last.

Sorry for the hijack.

Back to the OP. You will want to use a local print service. Shipping a large mounted print is expensive. I would recommend you get the print laminated if you don't have it behind glass.

That's assuming he by chance chooses a vendor with the same equipment.

If knows the questions to ask he stands a far better chance of getting a quality durable product.

If not.......

Frame shops and art supply places like Hobby Lobby or Michaels sell mounting board and spray glue. The trick is to get it straight and smooth. I use a clear photo spray to protect things I've printed on my inkjet printer.