How to fix sticky varnish on pine dining table?

Question

Hi, we have sanded back a pine tabletop, and applied Bondall Monocel waterbased clear wood varnish in three coats. The varnish was applied with a foam brush. This was done about six weeks ago.

Six weeks later the tabletop is still sticky to touch, and we have to be careful about what we leave on it. E.g. after leaving a notebook with black paper cover on the table for a period of time some black spots were transferred onto the surface that wouldn't come off with cloth and detergent. However, they did come off with mineral spirit.

Would be good if we could receive some advice on possible causes and solutions, other than sanding back again and application of a different product.

Thanks,

James

JacobZ · Answer

Hi @JLove,

Unfortunately, I would say adding more varnish, regardless of dilution, is unlikely to help and the likely solution is going to be sanding it back and reapplying in thinner coats when humidity is low.

You could try moving the table into a warm, dry, well-ventilated area for a couple of weeks to see if this helps. Gentle air movement and slightly higher temperatures can sometimes help a slow curing film finish harden further.

Considering the time frame already, I can't say it would work for certain, but it may be worth a try.

Unfortunately, I think sanding it back and starting again is likely going to be the only way forward, in which case, you can check out How To Restore Furniture, particularly the section on sanding, for some guidance on the process.

If you have any further questions, please don't hesitate to ask.

Jacob

JLove · Answer

Hi thanks @MitchellMc for the reply.  The varnish was definitely well mixed before application. The second coat went on an hour after the first, and the third about 12 hours after the second. Weather as I recall was a bit of rain in the time between the second and third coat but apart from that mild conditions. One suggestion I came across was to try applying a diluted coat over the top, but from what you're saying this sounds unlikely to help

MitchellMc · Answer

Welcome to the Bunnings Workshop community @JLove. It's wonderful to have you join us and many thanks for your question on coating timber.

I’m sorry to hear you’re having this issue.

A water-based varnish should definitely not still be sticky after six weeks, so something has likely interfered with the curing process. A few questions that might help narrow it down:

* Did you thoroughly stir the product before and during use? If it wasn’t mixed properly, the matting agents and curing components can remain unevenly distributed, which can affect how it hardens.
* How long did you wait between coats? If the second or third coat went on before the previous one had properly dried, it can trap uncured product underneath and prevent full curing.
* What were the weather conditions like at the time, particularly humidity and temperature? High humidity or cooler conditions can slow curing significantly, and in some cases moisture can become trapped in the film.

Unfortunately, if the finish hasn’t hardened after six weeks, it’s unlikely to cure properly from here. In most cases like this, the only reliable fix is to sand it back and reapply. I know that’s not what you were hoping to hear, and I’m sorry, but once a film finish fails to cure, there isn’t really a product that can be applied over the top to correct it.

If you do decide to redo it, ensuring thorough stirring, allowing generous drying time between coats (longer than the minimum recommended), and applying in mild, low-humidity conditions will give you the best chance of success.

If you can let us know the conditions and timing between coats, we may be able to pinpoint the likely cause more precisely.

Please let me know if you have any questions.

Mitchell