Light gaps are especially problematic on blackout shades where complete darkness is desired.
Do wood blinds block light.
Light blocking strips can cover gaps.
Besides their sleek and minimal appearance they are also excellent blockers of light and heat when they employ more than one sheet of fabric in their construction.
Although there are some blinds with fold flat slats that close tighter to block more light if you want to block a lot of light you re better off with shades.
Well this is possible but your room has to have no doors or windows.
According to the window designers choosing the smaller slat sizes will lower this risk while creating tighter closure.
Roller shades naturally have large gaps to the sides of the fabric so these light blocking strips are the perfect solution for maximum light control.
Ways to prevent the excess light.
Their cell pockets trap heat and light between them besides lending you the privacy that you desire at all times during the day.
Link to other question.
Are faux wood blinds room darkening.
Keeping the blinds close block most of the light but sometimes blind slats can let a little amount of light to enter your home through the gaps between slats.
All blinds with slats will let in some light through the spaces between slats.
Basically they can really block a substantial amount of outside light from coming into your room or area.
Also you have to keep in mind that it is block out all light is an impossible thing to do no matter how effective your shutter are.