Photodegration

[JamieP 14]

Could someone please explain the role of the three major components in solvents based stains during application, and the changes that occur to each throughout exposure.

Specifically pigment, and protection against UV.

How does it work? And what should a good product look like after 3 years?

[PressurePros 249]

The pigment is sacrificial. Transoxide pigmentation has the slower slope of degradation versus clay/earth pigments. Trans pigments are finely ground metals that are reflective. Transoxide pigments also allow more of the flaws in the wood/prep show through. With that being said, I have yet to see any sealer that looks good at 3 years. I am not sure what you mean by the other components. I am going to assume one is fungicide. Fungicide will migrate quickly from a non curing product. In the best case scenario with a good quality fungicide package and a curing oil/resin, you can expect 12-18 months of protection.

As far as bases go, I prefer oils. They are far kinder to the wood and actually serve to restore versus just carrying and locking pigment (like a waterborne)

[JamieP 14]

Thanks for the response.

As far as components I was referring to paraffin oil, mineral spirits, fungicide.

Is that 12-18 months horizontal or vertical?

At three years on a fence with a lighter color, there would more than likely be little to no pigment still present?

[John Orr 206]

Jamie, Ken didn't just "respond", he gave you (and all that read his post) an education! Thanks Ken and thanks Jamie for asking the question.

[Beth n Rod 1,279]

My responses in blue;

Could someone please explain the role of the three major components in solvents based stains during application, and the changes that occur to each throughout exposure.

Specifically pigment, and protection against UV.

Pigment for the most part is the UV barrier in addition to being an enhancement aesthetically. Additional UV protection is provided by ingredients which are colorless and help to either absorb or deflect UV light.

Absorption is modeled by a color shift and increasing darkness over time and exposure conditions.

How does it work? And what should a good product look like after 3 years?

After 3 years, most products on the market today will have lost their integrity from wear and exposure primarily. This will be represented by either fading or darkening of the finish.

Thanks for the response.

As far as components I was referring to paraffin oil, mineral spirits, fungicide.

Paraffin oil is a carrier and moisturizer and does not dry.

Mineral spirits is another carrier which keeps the product viable until application. As it evaporates, it creates heat and helps with the curing process.

A fungicide is an ingredient which helps to prevent mold growth and propagation from consuming the linseed oil in many formulations. It provides an initial defense and is short term in it's life.

Is that 12-18 months horizontal or vertical?

Vertical surfaces will always outlast horizontals surfaces 3:1 in general. Ken's figures were most likely horizontal which represents the majority of products on the market today.

At three years on a fence with a lighter color, there would more than likely be little to no pigment still present?

On a fence, there should still be pigment left along with signs of mildew growth mostly along the first 8"-12" inches. This is highly dependent upon the preparation, the application, and then the products abilities to last under the circumstances present. Shady conditions will provide for longer durability while western and southern sun exposed sections will show significantly more degradation overall.

Rod!~

[JamieP 14]

Thanks, greatly appreciated.

What about Sprinklers? What exactly causes the wood to not only lighten, but also to cause damage to the woods fibers, causing the affected areas to not be as receptive to the stain(Mineral Deposits + Chloride?). The darker areas that form usually on top of the arc is mildew correct?

How do you determine the difference between greying caused by UV damage vs Mildew?

Sorry for all of the questions. Hopefully the answers will help others as well.

[RPetry 564]

Thanks, greatly appreciated.

What about Sprinklers? What exactly causes the wood to not only lighten, but also to cause damage to the woods fibers, causing the affected areas to not be as receptive to the stain(Mineral Deposits + Chloride?). The darker areas that form usually on top of the arc is mildew correct?

How do you determine the difference between greying caused by UV damage vs Mildew?

Sorry for all of the questions. Hopefully the answers will help others as well.

Jamie,

I cannot help you on the sprinkler question, as we do very few fences and have never run into that problem.

At least here on the east coast of the U.S., greying of exterior wood is most often UV damage, although accumulated dirt can be a factor.

Mildew/mold/fungus is either green or black in color, not grey.