Porch floor painting is not a usual restoration topic (nor very interesting), so here's the executive summary: We did it, we were happy with it, then Really Bad Things happened to it.

First, the pre-prep: Scrape, scrape, scrape. All old paint that wasn't firmly attached had to be removed, and damaged wood should be cleaned up for repair. The tools needed are a metal (or firm plastic) scraper, a heat gun, a vacuum cleaner (or blower), and patience. Lots.

(At right: Candice using the vacuum to pick up paint chips)

None of the porch flooring dates back to the 1904-1905 construction of Comstock House, so keeping the existing wood wasn't a preservation effort; we could have ripped it all up to lay down new 1x4 tongue and groove Douglas Fir, as we did with the southeast corner. But except for two spots badly needing repair, the existing floor appeared in fine shape so there was no need for the extra work (not to mention, expense) of replacing it all. We wondered if that was the best decision, however, once work began and found that these sections had already been repaired once before, and with poor workmanship that made some of the problems worse. This meant that our fixes were probably going to be the last these poor old boards could take, so it was especially important to get the job right the first time.

A heat gun was the weapon of choice for this project because chemical stripper could seep into the gaps between boards and be impossible to completely clean up. Heat guns are wonderful tools, but caution can't be emphasized enough; besides the risk of burning yourself (or igniting your house), there's no telling what toxic molecules could be in the miasma of stink that wafts up from old paint melting under the focused heat. Always use a respirator and treat the heat gun with the care you would use with any other power tool -- just because it doesn't have sharp spinning blades doesn't mean it won't kill or incapacitate you.

The oil-base paint scraped up easily after it was softened with heat, but in the larger gaps between boards we found putty earlier had been used to level the floor before painting. Much of that putty had worked loose around the edges, allowing water to pool in these little valleys once the paint was chipped off. Putty is infamous for breaking free any time wood shifts position even slightly, much less when it's at the top of the front steps with constant foot traffic and vibration from the street.

With the cracked paint and putty wedges removed, we were left with a sorry-looking floor. My first thought was to fill those big gaps between the boards with a modern silicon sealer that would remain flexible. But the surface of these damaged areas still had to be leveled, as well as needing "buttered" transitions between old paint and scraped wood. Ultimately I filled the gaps AND leveled the floor using Restor-It epoxy. I'll write more about this excellent product in the future; we're now using it by the gallon on wood, and even concrete, repair.

Below is a before-and-after comparison of the damaged area in front of the stairs.









At left below shows the porch after epoxy and with the old paint scuffed up with an orbital sander for better adhesion. The sander was also used to feather transitions between the old paint and wood or epoxy. On the right is the porch primed with Zinser's Bullseye 1-2-3. It will never look this clean again.








Once the primer was down, the porch was blocked off for two weeks. Four days drying for the primer, then two coats of paint (Kelly-Moore French Sonnet KM3490-1 gloss, for my own future ref). It looked terrific. It looked REALLY terrific.

But about six weeks later, I noticed a small bubble on the southeast corner during the peak heat of the day. Then another, larger this time, also in mid-afternoon. And another. By the time contractor David Jessen returned to complete work on the railing, paint and primer were easily lifted up from the ends of the boards. "It's like picking at scabs," he mused laconically, "if you like that sort of thing," peeling off another fist-sized sheet.

I deeply feared that soon the whole porch would soon erupt into a mass of similar boils. The mailman would kick up clouds of off-white paint on his way to the mailbox; the cat would forge a smaller trail of exposed wood on her route between the front door and the sunny corner.

Everyone had a different explanation for why this was happening. The Benjamin Moore dealer who sold me the primer blamed the paint; the Kelly-Moore dealer who sold me the paint said no primer should've been used. (Can anyone explain why are all paint stores must be named "Moore?") I also asked the knowledgeable paint people at Friedman's Hardware where I had purchased the preservative used to treat the floor boards five months earlier; none of them had heard of such a problem, but implied that it was probably was my fault for stupidly not buying their brand of porch floor paint.

I experimented and observed. Was it the otherwise-reliable Zinser primer that failed? Following Kelly-Moore directions, I diluted their paint by 20 percent as a primer, and painted that over a peeled-up section. A few weeks later, that wasn't sticking to the wood either. I also found that there was no sign of any problems whatsoever on the old flooring -- the only paint coming up was on the porch corner where there was new wood. The primary suspect was now the two good coats of Green's Clear wood preservative that I had applied to the boards before the floor was installed.

Reading again the can of Green's Clear, the directions stated, "PAINTABLE WITH OIL BASED PAINT WITHIN 48 HOURS" (emphasis mine). Would that I could -- alkyd-based exterior paint is no longer legally sold in California. Zinser 1-2-3, however, boasts that it's "great for hard-to-stick surfaces" of all kinds. Could it stick to wood treated with Green's Clear? Apparently not.

I e-mailed Green Products Co. and explained my problem. Their response was that I should strip the paint and primer, then scrub the wood with TSP, followed by a solvent-based primer -- in other words, remove as much of their product as possible from the surface.

There's rich irony that Green Products, manufactured in Richmond, California, makes a product that really can't be used as directed in the same state. At the very least, the company should have warned buyers that their wood preservatives absolutely cannot be used with the allowed latex-based products. As I will spend the first rain-free weeks of summer scraping up the paint and primer on the corner of the porch, then scrubbing the surface down with TSP, then coating it with Preserva-wood, then more fresh paint, you can bet I'll dwell long and hard on how I'll never use a product of theirs again.



2 comments:

I am working on a similar project. how the did the epoxy you used hold up expansion and contraction from temperature and humidity changes?

April 24, 2013 at 8:12 AM  

Five years later, no problems at all, even in the most high traffic area. But take note that it is a very mild climate here, and that section of the porch is never exposed to direct sun or rain.

April 24, 2013 at 8:33 AM  

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