Sticky Varnish Problem on Wood: Causes & How to Fix

By MWB-Team •  Updated: 05/22/23 • 

After spending your time finishing a piece of wood with varnish, it’s time to let it dry before reapplying another coat. However, it can be frustrating for varnish not to dry and remain sticky or tacky. Different variables can cause a sticky varnish finish. The good news is it can be fixed. 

Although sticky varnish will eventually dry, it can take longer and not leave a smooth finish. In this article, we’ll explore why varnish gets sticky and how you can fix this problem. You can also check out this post to see other common problems you might encounter when varnishing wood.

Sticky  Varnish Surface Kitchen Island Table

Sticky Varnish Surface Kitchen Island Table

Why Varnish is Sticky/Tacky

1. Applying Varnish in Humid/Cold Conditions

If a varnish remains sticky for a longer time, it’s usually a result of applying it in a humid or cold environment. For the varnish to dry, the solvent in it must evaporate, which leaves the varnish film harder. However, with high humidities, the solvents mixed with varnish evaporate slowly, which causes it to be tacky or sticky.

Before you apply varnish, make sure the weather is good. Avoid applying varnish or other wood finishes in the winter or rainy season because this will affect how long it takes to dry. Warm sunny days are the best to apply varnish and other wood finishes.

2. You Applied Thicker/Too Many Coats

Most of the time, a sticky varnish also results from a too-thick application or adding another coat before the previous one has properly dried. Varnish already has a thick finish, and applying it thicker could prolong the time it takes to dry.

Applying a new coat before the previous one gets enough time to dry will also cause it to remain sticky. In the right conditions, you should let a recently varnished wood surface cure overnight before applying another coat.

3. Varnishing a Wet Surface

Most of the time, people apply a coat of linseed oil under varnish, thinking this will help. However, if you apply varnish before the oil cures, you’ll notice it will remain tacky.

Before applying varnish on an oiled wood, cure it fully for several days in a warm room. If you’ve already applied varnish, warm the wooden surface and give the varnish more time to harden. If that does not work, the only thing left is to strip it off and reapply it.

4. The Wood is Oily

Applying varnish to oily wood such as teak, cocobolo, ebony, or rosewood can also cause a sticky varnish problem. This is because the oils present in these woods prevent varnish from curing.

If the wood you’re using is oily, warm the surface and give the varnish more time to harden. If that does not work, strip the varnish and start over again. Before reapplying varnish to the oily wood again, wash it with non-oily solvents such as acetone, naphtha, or lacquer thinner.

How to Fix a Sticky Varnish Finish

1. Warm the Surface or Wait

Sometimes to fix a sticky varnish finish, you have to warm the wood’s surface or give it more time to dry up. It will prevent the varnish from drying up properly if it’s too cold or the humidity is too high.

To harden the varnish, warm the wood or allow more time for it to cure. To warm the wood, warm the area you are working in to raise the temperatures, which will help the varnish dry up faster. However, if that does not work, the only remaining option is to strip it and reapply the varnish.

2. Strip The Varnish & Reapply

Varnish is very difficult to repair and strip because of its good characteristics. It has excellent resistance to heat, solvents, acids, and chemicals. However, this usually applies to completely dried and cured varnish. In our case, the varnish is still sticky/tacky, which means it can easily be stripped and reapplied.

First, start by stripping the sticky varnish off the wood using a solvent-damp cloth or steel wool, or scrape it off carefully using a paint sprayer. After stripping the varnish, wash the surface of the wood with a solvent such as naphtha, lacquer thinner, or acetone. This should remove most of the varnish. You can then dry the wood, sand it a little, and reapply the varnish.

When reapplying the varnish, apply thinner coats to enable it to dry faster. A thinner first coat will also enable a better bond to the wood. This is because it will not only cure faster and harder, but also penetrate faster.

Reapply until you’re satisfied with the thickness of the finish. After that, you can leave it as it is or finish it with steel wool, sandpaper, or rubbing compounds. 

MWB-Team

Hello there! This is the Make Wood Better Team. Here, we share informative how-tos and guides focused on making wood better. Whether it's finishing wood, maintenance, or restoration, there's something on this website for you to learn and improve your skills.