Could I use stain blocker for old floorboards prior to using chalk paint?

[sani77]

I have pulled up the carpet and discovered hardwood floors. They are stained from the old black rubber carpet underlay though.

I don't own the apartment so can't afford to sand them properly, and the owners aren't going to fix up the place. 

I'd like to paint them with chalk paint, green, then white on top. 

I understand that the black stain will probably come through the paint. 

Is there a way to use a stain blocker instead of sanding them? 

It's temporary fix for couple of years until I move out, as then the owners will renovate and increase the rent! 

So trying to find a way to make them look pretty without spending a small fortune and a week sanding

[MitchellMc]

Welcome to the Bunnings Workshop community @sani77. It's fantastic to have you join us, and many thanks for your question about stain blockers.

It could possibly be a stain from the underlay, but the floors also closely resemble the natural look of aged hardwood. Years' worth of grime and buildup will end up looking like this.

We have the Feast Watson Satin Timber Floor Paint, but it's advised that the floor should be sanded to remove contaminants and ensure a smooth surface. To seal the flooring prior to applying the paint, you can use Feast Watson 1L Proofseal. This should help prevent any staining from bleeding through the top coat.

I just wanted to point out that painting flooring is a somewhat permanent finish. The paint will seep between the boards and coat their edges. If the owners did want to refinish the floors by sanding them and varnishing, that paint between them might be just about impossible to remove. So, before moving forward with your painting idea, you'd want to be sure that the owners entirely understand the repercussions of painting the floorboards.

Please let me know if you have any questions.

Mitchell