heatbed lower or higher with warping?

Hello guys

I searched about this topic very much but i couldnt get a satisfying answer. so here is one for you all.

I have a mendel90 and mostly printing in PLA and most of the time i dont have a problem with warping corners but now im printing a larger flat area i have these little "ears" curling up from the heatbed.

Im currently printing at 185 degree and the heatbed at 65 (first layer 67). layer thickness 0.25mm
Should i lower the heatbed temp or higher it and why?

specific the why because i could come up with certain theories why yes and why no lol

Tnx in advance guys

Weedz

lift at the corners is likely due to a drooping temperature profile in the heated bed.

My recommendation?

1) insulate your bed to reduce loses as the distance from center increases
2) add a brim. it acts like tape to keep the perimeter in place.

I'd avoid increasing the bed temp, since that will lead to sag as the extrusion's core "resting" temp increases (ie, the core temp in the 5-10 layers right above the heated bed)

tnx at the moment my heatbed is resting on a piece of MDF covered by glass were i print on....
Ill check the insulation bit but i think its insulated pretty ok

will have a go at the brim