Troubleshooting problems encountered when using Sikkens Cetol

Sikkens Cetol prides itself on being an easy-to-use, forgiving product but naturally, instances will occur where it doesn’t work as hoped. Some problems can be attributed to surface prep, while in other cases, the product did not cure as it should, usually due to a contaminating substance or environmental conditions.

PROBLEM: BAD ADHESION OR DOES NOT CURE SMOOTHLY
CAUSE: IMPROPER SURFACE PREPARATION

Improper surface preparation and surface contamination are the main causes of bad adhesion, or of the finish not curing smoothly. Surface preparation is the fundamental beginning to a good or bad Cetol experience. The wood surface must be free of any contaminating substances. If contaminants are not removed, Cetol will not be able to bond to the wood.

On new wood, Interlux recommends wiping the wood with their Special Thinner 216 to remove contaminants, sand smooth, vacuum, then wipe again with Special Thinner 216. Prior to applying Cetol, do not use mineral spirits, or any other materials that are not specifically listed because these may actually be contaminants.

On previously coated (with non-Cetol products) wood, Interlux recommends removing all existing coatings completely, then wipe with Interlux Special Thinner 216. Sand smooth, vacuum, then wipe again with Special Thinner 216.

On weathered or previously oiled wood, Interlux recommends using a teak restorer, as directed by the manufacturer, allow to dry, then wipe the wood with their Special Thinner 216. Sand smooth, vacuum, then wipe again with Special Thinner 216.

On wood that has persistent blue fungi and mildew, Interlux recommends applying a teak restorer, as directed by the manufacturer, allow to dry for three full days, then wipe the wood with Interlux Special Thinner 216. Sand smooth, vacuum, then wipe again with Special Thinner 216.

PROBLEM: BUBBLING OR IMPERFECTIONS BENEATH THE FINISH
CAUSE: THE WOOD HAS A MOISTURE CONTENT HIGHER THAN 18%

In the surface preparation for Cetol, it's also indicated that the wood’s moisture content must be less than 18%. Though most people don't have a meter for measuring moisture content, it's crucial to make sure the wood is not too moist. To make the wood dry enough, it may take 1-2 weeks of dry, controlled weather. If the wood is near the point of being ‘wet’, Cetol is a solvent-based formula, and the saying that ‘oil and water don’t mix’ becomes a problem. High moisture content can lead to expansion/contraction issues with finishes, the moisture coming out over time or in warmer conditions, which forces the Cetol to bubble, or even develop mildew issues under the finish.

PROBLEM: PRODUCT DOES NOT CURE PROPERLY OR IS STAINED BY WATER DROPS
CAUSE: PRODUCT APPLIED TOO THICKLY OR APPLIED AT INCORRECT TEMPERATURE

Some customers have run into instances where the Cetol stays tacky for days, or it becomes affected by water drop stains days after the last coat was applied. Sikkens Cetol is an air dry product that cures at a rate that is dictated by how thickly it was applied, as well as the environmental conditions. It also does not cure to a very hard material for a number of days, despite being tack free to the touch. This is part of the reason that Cetol will accept being overcoated without sanding.

Typically, marine wood finish products like Cetol will dry a little slower when applied thickly. Also, temperature and humidity can play a big role. If the product is applied at the minimum temperature of 50°F, it will cure. But if it's applied at 50°F and the temperature settles into the 40s (or lower) at night, that is below the necessary temperature for curing. Cooler temperatures also have an increased chance for dew. Moisture like this can adversely affect the cure, or the appearance of the finish.  

To fix cosmetic issues and blemishes while applying the first few coats of Cetol, scuff with an abrasive pad and apply a new coat. If the Cetol is wrinkling or peeling from the surface, the issue lies beneath, and the contaminant must be dealt with from beneath the wood finish. Remove the coating and try to isolate the issue.