ANTIQUE PAINTING OF FLAMENCO DANCERS HAS RED BACKING?

I posted this painting along with another painting titled 2 Unknown Paintings - asking for help with the signature. I decided to put it on eBay but wasn't sure if it was on canvas or board, so I opened a corner of the back - I thin it is a canvas on something all red (below) What the heck is the red? Does it help age it?
Thanks

 

I don't honestly know -- but I think it may be like under-painting gold leaf with red. More um...oomph, so to speak.

Would somebody help me out with this. Please.

 

You can see the canvas wrapped around the edge of whatever the red thing is? Maybe they just found something to give canvas support?

 

Journey, it is not antique. It has just been in a home with heavy smokers.

 

Looks like canvasboard with a red paper backing

 

Is the white area the canvas?

 

Yes

 

Definitely not antique canvas. It does appear to be canvas board but if you can pull a few nails and lift a corner, you will know for sure.