Sunday, March 19, 2017

Applying Lifeline Finishes Over Penetrating Oil-Based Stains

By Perma-Chink Systems, Inc.
Reprinted from our LogCore newsletter Summer 2014 edition

We often get asked if it is acceptable to apply a Lifeline finish systems over an existing oil-based stain. It would be nice if there was a simple yes or no answer to this question but there’s not. It depends on a number of factors including how many coats have been applied, how long the stain has been on the walls and which oil-based stain are we talking about. In general it is ALWAYS best to remove an existing competitive finish before applying Lifeline. All too often a homeowner has no idea what is on the walls let alone how many coats were applied. What they do know is that they want to apply something on top of what’s already there to avoid the cost and effort of stripping the surface down to bare wood. This approach is very risky, especially with a water-based, high performance film-forming finish like Lifeline. Let’s look at some of the individual parameters that have to be dealt with.

Appearance: Perma-Chink’s Lifeline stains are transparent finish systems. This means that any discolorations or residual pigmentation that remains on the wood will show through our finish systems. With few exceptions our finishes have little or no hiding power. Once our Lifeline system has been applied it essentially locks the surface of the wood in place and if you are dissatisfied with the final look and appearance it can be quite costly and time consuming to remove the finish, take care of the discolorations, and start over again
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Adhesion: How much residual oil still remains in the wood and is it enough to interfere with the adhesion of Lifeline? These are questions that are just about impossible to answer. Yes, a small test area may quickly determine that there is a problem but if a problem does not show up within a few days there is no way to tell what may happen over a period of several months or years. We have seen several issues that were directly attributed to the prior application of oil-based stains. Peeling occurred around checks and fissures because they had been flooded with an oil-based product during the initial staining process and although most of the oil had evaporated from the surface of the logs the checks had retained enough oil to reduce the adhesion of a water-based film.

Blisters: When several coats of an oil-based penetrating stain have been applied to a wall within the course of a few years the underlying wood can become so saturated with oil that it may take a long time for it to evaporate. When a homeowner finally decides that it’s time to change to a quality finish like Lifeline pressure washing with water may appear to remove most if not all of the residual oil pigments and prepare the surface for the Lifeline finish. The wood may look clean and bare but in reality the old oil carriers may still be in the top layer of wood. With the application of the first coat of Lifeline these oils are now trapped in the wood. Yes, our finishes breathe water vapor but oil molecules are much larger and can’t make it through the film. Now weather comes into the equation. If the days stay cool and cloudy until the entire finish system is applied and has time to cure there’s a good chance that nothing of consequence will occur. But if the sun comes out and heats up the wall while the finish is still soft and pliable the oils contained in the wood will begin to evaporate creating blisters in the finish.

This can occur after the first coat, second coat, or the entire finish system has been applied. One thing that these types of problems have in common is that they typically show up within a week after application.

If you plan to apply Lifeline after having applied a penetrating oil-based stain what is the best way to minimize the chance of forming blisters? The product to use in these cases is S-100 Finish Remover. S-100’s formulation includes a strong detergent package that will help make the residual oils water soluble and easier to wash away. Once the finish is removed using S-100 allow the surface to remain bare for a couple of months to allow any remaining oil to evaporate. When you are ready to stain, wash the surface with Log Wash, allow it to dry and apply the first coat of Lifeline.
©Perma-Chink Systems, Inc.

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