Wood Restoration and Finishing

My deck finish is bubbling, blistering, lifting or peeling. What’s going on and what do I need to do to fix it?
What type of finish is “best” to apply to decks?
How does deck cleaning differ from deck stripping?
How hard is it to strip a deck?
How come your wood restoration services include prices for labor and stain separately?
I’ve got black spots on my deck, what is it and what do I do?
Why are there black “streaks/marks” on my cedar or redwood deck around screws and nails?
My deck has “rings” or other marks on it, why?
Do You Apply Custom Tinted Stains?
What is Mill Glaze on New Redwood and Cedar?

Wood Restoration and Finishing

1. My deck finish is bubbling, blistering, lifting or peeling. What’s going on and what do I need to do to fix it?

Your deck has what is known as a “film forming” finish on the deck surface. Basically, you have what amounts to be a “layer of something” on the surface of the wood and moisture has gotten below the finish surface and is causing the finish to fail. This is a common problem for outdoor wood surfaces, especially the horizontal boards of decks. If you cannot “seal” all six sides of a board and keep it sealed, moisture finds its way under the coating. Moisture migrates into the wood through unsealed areas, around nail/screw heads, cracks in the board surface, etc. and cannot escape because the “majority” of the board is sealed. When moisture cannot escape, it ultimately causes the finish to loose adhesion with the wood surface and the finish fails.

Your choices to remedy this problem are two. Chemically strip the existing finish off the wood, or physically sand the finish until it is removed. Neither is fun, nor inexpensive. There are no other choices, other than replacing the deck. Refinishing over the failing surface will just result in failure of the newly applied finish in a few short months. You now understand why Hydro Scrub does not recommend the use of any “film forming” finishes on wood decks.

2. What type of finish is “best” to apply to decks?

This is another one of those questions we cannot cover in detail here because it will take two or more pages to respond. However, our basic feelings are as follows. Hydro Scrub recommends the application of penetrating finishes to decks. Film forming finishes, as discussed above, always fail, and when they do, the deck owner is in a real bind. The owner must either spend a large sum of money removing the failing finish (sometimes at a cost approaching the cost to build a new deck once stripping, sanding, and reapplication of finish material is completed) or simply replace the deck. Penetrating finishes don’t fail per se, they simply weather or age. When a penetrating finish weathers, the deck has only to be cleaned, allowed to dry, and the finish reapplied. There is no stripping, sanding, etc. when working with penetrating finishes. There are very few true penetrating finishes in the marketplace…many which say they are, are not.

3. How does deck cleaning differ from deck stripping?

The simple answer is that deck cleaning will not necessarily remove the existing finish material from the wood surface, while deck stripping is designed to remove existing finish materials.

Deck cleaning uses relatively environmentally safe chemicals (sodium percarbonate [aka, Oxy-Clean], sodium hypochlorite [aka, bleach], and surfactants [soaps]) whereas deck stripping uses very harsh chemicals (sodium hydroxide [aka lye]). There is rarely, if ever, any damage to plants and surrounding vegetation when deck cleaning, however, deck stripping can and often does result in stressed or impacted plants and vegetation.

Deck stripping also results in the need to neutralize the stripping chemicals with acids so as to provide a proper pH level for the wood. Some contractors also apply the same acids to decks which are only cleaned; however, this step has become a topic of controversy over recent years.

Deck stripping materials containing sodium hydroxide can cause severe skin burns and irreversible eye damage, including blindness, if splashed in the eye. Sodium hydroxide strippers are highly dangerous products and are best not used by homeowners.

Deck stripping will also usually require sanding of the deck prior to finish application. This is because the wood fibers of the deck are severely damaged during stripping operations and some of the fibers simply do not “release” from the wood surface when washed, resulting in a fibrous or fuzzy deck appearance. This fuzzy or fibrous appearance can also occur as a result of using too much pressure while washing wood surfaces and can also occur if the wood has been neglected for too long and is simply cleaned.

4. How hard is it to strip a deck?

That depends on the finish material currently on the deck. Some finishes strip relatively easy, but others are quite difficult. Keep in mind, that if you desire to strip a deck so that you can apply a “natural” (i.e., transparent) finish material, if you do not get all of the existing finish material off, your deck will look blotchy, spotted and probably pretty darn ugly when finished. If you are going with a natural finish, you need to get all the existing stain off, including those areas under the handrails, under built in benches, between the floor boards, etc. Not 95%, not 98%, but as close to 100% as you possibly can. This can take serious amounts of labor and chemicals. Usually, stripping decks is not a task for the homeowner. Additionally, many homeowners, once they find out the true cost of deck stripping (e.g., materials, the added steps of neutralizing and sanding) often elect to not strip their decks. The cost to correctly strip a deck can vary greatly….sometimes 200% of what you think it will be. Hydro Scrub only conducts deck stripping work on a time and material basis.

5. How come your wood finishing services include prices for labor and stain separately?

Hydro Scrub provides two costs when quoting prices for wood finishing because generally we use penetrating finishes and the quantity of finish material is highly variable based on the condition of the wood. We quote a firm fixed cost for the labor aspect of wood projects, while the quantity of finish material is estimated based on our experience with your projects type and condition of wood. Excessively dry wood will take considerably more stain that properly maintained wood.

Hydro Scrub prices our work in this manner simply to make it fair and balanced for both us and you. Too many contractors low bid a wood project with a low amount of stain included in their price in order to just get the job. These contractors will be gone in a year to two because their quality is poor. The customer will rarely notice the “problem” and when they do, it’s long after the job has been completed and the invoice paid. Think about this the next time you are comparing contractor proposals…..it takes essentially the same amount of labor time to finish a given deck with three or seven gallons of penetrating stain. The contractor just applies the stain heavier. However, those additional 4 gallons of stain, if necessary for a dry deck, adds anywhere from $120 to $150 to your project, plus tax. That’s a big dollar difference on a $500 to $700 deck project. If you shop price and only price, the low bid contractor will get the project, but you will not be happy with the appearance of your deck 3-6 months latter when the insufficient stain quantity starts to show problems. That is the reason why Hydro Scrub’s wood finishing contracts are estimates...we are uncertain as to the amount of stain your deck will take, but we apply whatever is required for it to be properly restored. You are then invoiced accordingly.

6. I’ve got black spots on my deck, what is it and what do I do?

First, can you “feel” the spots or not? If the spots feel like a little bump equal to maybe a pencil point, the spots are likely to be artillery fungus. Artillery fungus usually doesn’t occur on horizontal deck surfaces, but it can. If you can’t “feel” the spots, then the spots are most likely mold and mildew. Let’s assume it is mold and mildew.

Next, you need to determine whether the mold/mildew is “on” your deck finish or “under” your finish. To determine which, you need to take some diluted household bleach (wear rubber gloves and don’t get the bleach in your eyes) and water. Mix up a small solution of 1 part water and 1 part bleach, squirt some dish soap in as well and pour it on small test area of the deck. Do this in a hidden spot if possible. Brush the area lightly about 2 minutes after application and then again at about 8 minutes. Keep the test area wet with the bleach/water solution, as needed. After 10 minutes, hose the area off with a garden hose. Are the spots still there? If so, the mold/mildew is “under” the finish material and you will need to strip the finish to remove the mold/mildew. If the spots are gone, congratulations, they are “on” the surface of the finish and the deck can be simply cleaned.

7. Why are there black “streaks/marks” on my cedar or redwood deck around screws and nails?

If your deck is constructed of cedar or redwood, it should have been built with stainless steel fasteners and if not, at least coated fasteners. If the deck was constructed with uncoated fasteners, the black streaks/marks are a reaction between the untreated fastener and the wood. There is a pH reaction causing the marks which are actually the tannins from the cedar or redwood. The marks can probably be removed with oxalic acid, but they will return. Unfortunately, too many homeowners reject the use of stainless steel fasteners when their cedar or redwood deck was built due to the high cost of the fasteners, but this is a big mistake. Other than routine treatment of the deck with oxalic acid to push the black streaks marks back "into" the deck, there is no solution if you wish to maintain a natural wood appearance.

8. My deck has “rings” or other marks on it, why?

“Rings” are probably a result of planters or umbrella stands being placed on the wood surface. Wood is wood and if you don’t treat your deck like a fine peace of wood furniture, it can show water stains and marks just the same. Try placing nylon glides or spacers underneath all items which make contact with the wood surface. Other marks on your deck can be from BBQ drippings, plant fertilizers, and mill stampings (ink markings from the wood manufacturer).

9. Do You Apply Custom Tinted Stains?

Hydro Scrub will gladly work with you on the selection of your custom tinted stain, however, we will not purchase any custom tinted stains without payment for such stains in advance. Custom tinted stains are not returnable and unfortunately, we have been “stuck” with such materials in the past through no fault of ours. Therefore, Hydro Scrub strongly recommends that you obtain the smallest sample of your prospective custom tinted stain, apply it to your wood surface, and make sure that the color matches your expectations after drying and before purchasing it in quantity.

10. What is mill glaze on new redwood and cedar?

By: R. Sam Williams and Mark Kanebe, Chemists
Wood Finishing Research
USDA Forest Service
Forest Products Laboratory
One Gifford Pinchot Drive
Madison, Wisconsin 53705-2398
October, 1995

A condition known as mill glaze (also called planer's glaze) can occur on smooth flat-grained western red cedar siding and occasionally on other species, such as redwood. There is controversy over the exact cause of this condition, but it seems to be a result of using dull planer blades and is exacerbated by the difficult-to-plane flat-grained surface of the lumber. In vertical-grained wood, the earlywood/latewood bands are perpendicular to the surface. Because of this perpendicular orientation, vertical-grained lumber is easier to plane, even with dull tooling. Planning causes two distinct changes to the surface of the lumber-- it burnishes the surface and crushes some of the wood cells.

During the planing or milling process, overheating of flat-grained siding may bring more water-soluble extractive to the surface, creating a hard, varnish-like glaze. Excess water-soluble extractives can also form on the surface during kiln drying. As these extractives age, particularly in direct sunlight, they become insoluble and difficult to remove. If these extractives occur prior to final planing or sanding of the lumber, the final surface preparation usually removes them. The wood surface can be tested for this glaze by carefully placing a few drops of water on the surface prior to finishing. If the water beads and resists soaking into the wood, the surface probably has mill glaze. Light sanding of the surface will remove this glaze.

The second factor usually found with the glazing on flat-grained wood is crushed earlywood on the pith-side of lumber. Dull planer blades tend to burnish the surface and crush the less dense earlywood bands directly beneath the more dense latewood bands at the surface. Later, when these boards are exposed to weather, the crushed earlywood absorbs moisture and rebounds, causing the surface latewood bands to rise.

These two surface defects act in concert to cause flaking of the finish parallel to the grain. The pith-side of flat-grained lumber finished with a single coat of oil-based solid-color stain is particularly susceptible to his type of finish failure.

Sanding will remove the extractives build-up, but it is not likely to remove all the crushed wood and subsequent wetting will continue to cause the surface to deform. Exposing the wood siding to the weather for a short period may help to condition the surface. One or more wetting and drying cycles are necessary to remove these planer-induced stresses in the wood. However, wood should not be exposed to the sunlight for more than 2 weeks before application of a film-forming finish, because this exposure decreases the adhesion of the coating.

The simplest and best solution to the problem of mill glaze, when using flat-grained bevel siding, is to install the siding rough side out. The rough side is the side of choice for application of penetrating semitransparent stains. Solid-color stains form a film and will give a much longer service life when applied to the rough-sawn side. In addition to the lack of mill glaze, the rough side has two other advantages. The film build on the rough side will be greater, and the film will have greater mechanical adhesion or "bite". The best film build is obtained by brush application. If the finish is applied by roller or spray, it is advisable to back-brush the stain immediately following application to even out the finish and work it into the surface of the wood, thus avoiding bridging, gap formation, and lap marks. If the flat-grained siding must be installed smooth side out, remove the planing stresses by wetting the surface, then allow 4 to 5 days for the surface to dry before finishing. Scuff sand the surface of the wood with 50-80 grit sandpaper prior to finishing.

Hydro Scrub provides services in Berks, Lehigh, Montgomery and Northampton Counties, including the following areas: Alburtis, Allen, Allentown, Ancient Oaks, Bally, Barto, Bechtelsville, Bethlehem, Boyertown, Breiningsville, Catasaqua, Center Valley, Cetronia, Coopersburg, Coplay, Dorneyville, East Allen, East Greenville, East Texas, Easton, Emmaus, Fogelsville, Fountain Hill, Freemansburg, Green Lane, Guthsville, Hanover, Heidelberg, Hellertown, Hereford, Ironton, Kuhnsville, Kutztown, Limeport, Lower Macungie, Lower Milford, Lower Nazareth, Lower Saucon, Longswamp, Lowhill, Macungie, Maxatawny, Mechanicsville, Mertztown, Neffs, North Catasaqua, North Whitehall, Northampton, Orefield, Palm, Pennsburg, Red Hill, Salisbury, Schnecksville, Shimerville, Slatington, South Whitehall, Summit Lawn, Topton, Trexlertown, Upper Macungie, Upper Milford, Upper Saucon, Vera Cruz, Weisenberg, Whitehall, Whitehall, and Zionsville. Zip codes serviced include: 18011, 18017, 18018, 18025, 18031, 18032, 18034, 18036, 18037, 18041, 18049, 18051, 18052, 18053, 18054, 18055, 18056, 18060, 18067, 18068, 18069, 18070, 18073, 18076, 18078, 18080, 18092, 18101, 18102, 18103, 18104, 18105, 18106, 18195, 19503, 19505, 19530, 19539. Interactive Service Area Map

Hydro Scrub | PO Box 552, Macungie, PA 18062 | Phone: 610-966-3500 | Contact Us | Facebook
This site includes Hydro Scrub Photography | Copyright ©2008- 2011. All Rights Reserved. | Hydro Scrub is a Registered Service Mark.