Revarnishing wooden floorboards

[Catchthepigeon]

Hi
I'm looking for a little bit of advice!
About 4 years ago we had our floorboards sanded, stained and varnished. We now desperately need to revarnish but not sure best way to do. All advice I've read suggests the need to completely resand, stain and varnish again. With a 3 year old and 8 month old in the house this fills me with dread.
So, do you think it would be possible to lightly sand to lift off any remaining varnish and revarnish?! Or any other ideas? We tested just putting varnish on top and it's stayed tacky!
Thanks in advance!

if coating on top, you should use the same kind as you used before.

Is it dull and scuffed, or has it worn through?

Was it tinted?

Thanks for your reply! It's dull and scuffed and was a clear varnish originally (not sure which brand though!). The boards are stained a walnut colour underneath.
Maybe we try another brand on top on a test patch before doing anything more drastic!

As long as the dye is not worn away, you can revarnish.

It is good practice to use a wood dye followed by clear varnish. If they had used a tinted varnish the colour would have been irregular as it goes thin in areas of wear.

We have been using osmo oil on our floors. You can use clear stuff over the stain and it's much easier to fix in patches than varnish and less shiny. Might be worth considering? The finish is still varnish-like, it doesn't soak in like I thought oil would before we used it!!

Be careful with using what you think is the same varnish as you've used previously. I recently did this, only to find the formulation had completely changed. The results were not pretty!

Thanks all, I think our problem is that there is still varnish there its just dull now and worn in places so I think we may have to try and lift what is there before revarnish or oil (if a test patch of just going over the top doesn't work!)

use a fine or medium paper on a cork block, and sand just enough to take the shine off before recoating your test sample. It must be perfectly clean and free of grease, dirt or polish.

Thankyou!