Do you mount on mdf, foamcore, etc

Hi guys and gals, I've tried searching the forums but cant to much info on this. I have a company that prints my photos, they send them to me, i also use a framing company that i buy frames from, that come with the matboards.
I then use backing tape to stick the photo to the mat board,then put the mat/photo onto glass and then put the mdf that comes with the frame in behind the mat/photo but i dont get that really flat look. There is still some curves in the photo.
My question is what do you pros use to stick your photos onto before putting them into frames.
I've heard of foamcore (but heard it breaks apart after time)
The mdf which if it gets humid it can warp
Rencently heard of sticking the photo onto a sheet of alluminium
But heard that glues are acidic and can discolour the photo.
I'm stuck as i want my end product to look pro and to last,
I'm in Australia so if any aussie pro's can point me in the right direction it would be great
Thanks

Anyone can answer this, not just aussies!!!! Please help

Foam core

What do you use to stick the photo to the foam core mount?

thecackster wrote in post #11109640
Foam core

My wife has done a lot of framing. Just attach photo to mat with acid free linen tape. Foam core just lays against picture. It should lay flat. Some paper is harder to deal with.

#1 Double weight board.
When its a big print i may use Gatorfoam
You can get it with adhesive peel and stick.

I know a lot of rubber cements are acid free, I have used elmers brand rubber cement to glue the photo to foamcore before

mitch.mccabe wrote in post #11109813
What do you use to stick the photo to the foam core mount?

There is this great adheasive from 3M that i've used, comes in rolls. Basically what i do is peel it, and stick it to the back of the print, cut it to size. Then I stick the photo to the foamcore, and trim the excess. The key is to keep a very sharp blade at all times and use a straight edge to keep from making wavey cuts or screwing up your print.

thecackster wrote in post #11119079
There is this great adheasive from 3M that i've used, comes in rolls.

3M Positionable Adhesive.

krb wrote in post #11119157
3M Positionable Adhesive.

Ah thats it! Thanks! Monday morning, brain not quite fully functional yet.