wood furring... various issues

[hoosierwindowtek 14]

Hi, all, haven't posted for a while, but I've been reading and learning a lot, thanks!

I've been reading and searching, but wanted to ask this as a combination of questions. I just recently finished a 16'x16.5' deck, strip/brighten/seal. When I was done with the strip, I was a bit disappointed with the amount of furring caused, even though I tried to be very careful. The deck is a very neglected PT deck that was very grey and green with algae. I used RipIt from sunbright to strip, and I use a 2500psi/2.5gal/minute pressure washer with a #5 nozzle @ 25 degrees. I think I'm getting about 1000 psi with that nozzle.

The questions: How much furring is acceptable/unavoidable? How much work do you put into sanding when furring is present? And, finally, how do you factor in the time to deal with sanding in your price when you don't know how much time it's gonna take before you start?

Thanks for the help!

[bigchaz 157]

With wood that old and neglected it can be almost inevitable at times. Since your machine has a lower gpm maybe the tendancy was to hold the nozzle closer to the wood to speed up rinsing? Even though you used a larger tip you still want to keep the gun far enough away from the wood

Sanding is always included in my bids, which is why I work hard not to have any furring. Otherwise I use the makita with defurring pads. 60 grit random orbit sanding if there are bad spots.

[plainpainter 217]

I've had really bad luck with furring this year - and to be honest I don't know how to charge for all the sanding. For now I am just eating the labor on the sanding part - trying to build up a clientale - and then hopefully, when I am not so 'hungry' I will offer sanding as an upsell. But I have done decks the year before that came out perfect with absolutely no sanding - but this year hit a bunch of winners.

[James 625]

Did you prewet the surface of deck or soak the deck with Ripit.Makes a difference IN the out come.

[dsp powerwash 14]

Prewetting as jim said helps, but if the deck was real neglected there probably wasnt much old stain to remove and you may have mixed the stripper to strong or let it dwell to long. frank

[hoosierwindowtek 14]

I'm not sure there even was any stain, just maybe some thompson's or something else clear.

I might have let things dwell too long, I'll watch that in the future, but the thing that confuses me is that once I finished rinsing, there were still little spot areas with what I think was mildew that were black, so I guess I didn't get enough chemical on those areas. It seems a bit tricky to kill all of the growth without harming the wood.

[bigchaz 157]

With a lot of stains you can get mildew and mold under the surface of the stain you strip. You strip the top stain and then rinse and the mold hasnt been touched fully. Might need to spot treat those spots or do a real quick second stripping

[MMI Enterprises 289]

Without fur what would the old dead gray stick to....without black spots what would them BDA gurus do.. :)

My outlook is some wood will just fur regardless of stripper or pressure as it is the left over fiber laying underneith the gray. The good stuff has been leached out so it takes a fur shape like microscopic peaks and valley's or a wave form. Prewet probably has something to do with removing the peaks and minimizing the valley by way of sealer or gray not ripping into them on removal. High pressure usually causes splintering abit different then what most would call fur. I seen fur with just mild wood cleaners and garden hose so...

[James 625]

The older the wood (cedar , PT, Redwood)the less furring You should get. With the correct solution, pressure and volume of water the top layer of degraded wood becomes easier to remove the longer it sits. Trying to remove the wood that has grayed (degraded) in the first two years of weathering is more of a challenge and produces more furring. Because it hasn't degraded enough to be remove! If you Furr wood older than 4 years old you used to strong of a solution or to much pressure. The solution you use probably went beyond the degrade wood and affected the new surface.

If you prewet or dampen the surface it will protect the new surface .You might want to start with a precarb. It will not attack the new surface and will prevent furring old wood . With bad mold you may have to do it twice. I stay away from using Sodium Hydroxide on bare wood.

[MMI Enterprises 289]

James, I pretty much concur except that I did get some fur on a real old heartwood deck this summer while using percarb and 600psi. I generally don't use hydroxide on just bare wood neither..

Where does the hypochlorite come to play on this? Like where abouts on fur causing behavior does it sit compared to hydroxide, percarb, pressure, or age of wood? :)

[Beth n Rod 1,279]

On a neglected deck, no matter what method employed, furring will occur.

The grey fibers are not all going to go quietly. Some will remain to the extent of requiring removal by mechanical methods.

Prewetting may help minimize furring in some cases but it is not always going to avoid the problem.

Stripping a deck of an old product with chemicals is like turning an hourglass. Once you apply an active chemical, they will work consistently and equally while wet and active. Problem is, previous applications of product are never consistent in thickness and wear is not uniform either. What you have is an unbiased reaction happening all over at the same rate no matter the thickness of the product. Where it is thin, the reaction will reach wood sooner than in areas where the application is thicker or more durable for that matter. Since you cannot stop the reaction in one place over another, you will end up with areas that will fur up on you unless you learn how to finesse the chems and apply them to the most common problem areas first such as rail spindles and under the caps. This also gets the proximity areas on the floor which catch the overspray or drips of the previous application. Apply to areas that have been protected such as under tables and chairs, storage boxes and mats as well before applying to high traffic areas and rail cap tops.

Learning where the problem spots are before applying will help you to control the reaction better to your advantage. Regardless, you may still want to plan on defurring each deck as a rule of thumb. Get a few osborn brushes and a 7" variable speed buffer to do it with and wear respirators while working. Remember that you will be breathing pressure treated wood and small wood fibers which can irritate the lungs and cause what is similar to black lung disease if you don't.

We anticipate furring and have the process included in all our bids so that the wood is as smooth as possible. Good luck!

Rod!~

[James 625]

Kev, your solution wasn't strong enough or it didn't dwell long enough ? I don't use precarbs unless I'm out of bleach ( which happened the other day). I don't have issues with furring unless I srcew up, it's under 2 years old, It's a hardwood, or stripping.

The other day I thought I was just washing a regular customer's house. They added 7 pieces of teak, 40 year old Redwood deck(never sealed) I cleaned 4 years ago, Blow out gutters and bleach down roof. Didn't have enough bleach so I precarbed the teak. Worked out great!

Bleach will fur if it's to strong, left on to long and while smoking a Bong!!

[MMI Enterprises 289]

That perticular deck had no finish and I got through the gray easy enough with the percarb. Think it might have been a percarb/tsp mix actually. Will just have to take your word James that if I would have went even deeper I would have ran out of fur to a smooth wood but honestly I doubt it. Just think it was going to do it no matter what.

[Beth n Rod 1,279]

Bleach will fur if it's to strong, left on to long and while smoking a Bong!!

It would suck if you forgot which one to take a hit off of! :lol:

Sorry, couldn't resist kidding around with James...

Rod!~

[sealwizeofatlanta 14]

When using an osborne brush to defur, when are you sanding? Are you sanding when it is still wet, or after it drys? If sanding is done after the wood drys, then I have a concern about the dust clogging the wood pores and therefore not accepting the sealant and/or stain. I mainly see defurring on spindles, and am seeking any advice.

Thanks.

[MMI Enterprises 289]

When using an osborne brush to defur, when are you sanding? Are you sanding when it is still wet, or after it drys? If sanding is done after the wood drys, then I have a concern about the dust clogging the wood pores and therefore not accepting the sealant and/or stain. I mainly see defurring on spindles, and am seeking any advice.

Thanks.

If one was to use an osborne then they likely not gonna also be sanding.

Either is to be done while dry. You souldn't have concern about clogging. Your goal is to remove fur and to remove the peaks and valleys of the pores to a smooth finish. You can not clogg them being the wood you removed is loose and it just blows away. In other words a sanded wood particle is no wheres near the small size of a pore to be able to go in and it won't grip to it's counterpart that you had just removed it from. Only such case where any such thing can occur is when ya didn't sand wood smooth or it is severly cracked up and compromised. Blower or broom cleans those right out though prior to staining. Heat burnished surface causing lack of penetration is another topic..

Edited October 30, 2008 by MMI Enterprises

[RPetry 564]

When using an osborne brush to defur, when are you sanding? Are you sanding when it is still wet, or after it drys? If sanding is done after the wood drys, then I have a concern about the dust clogging the wood pores and therefore not accepting the sealant and/or stain. I mainly see defurring on spindles, and am seeking any advice.

Thanks.

James,

Softwoods do not have "pores", only hardwoods. I would imagine being in Atlanta, you mainly see Southern Yellow Pine which is a softwood.

[Beth n Rod 1,279]

Rick is correct,

Here is an excerpt from our companies training guide:

Many structures being constructed are comprised of but not limited to Cedar, Redwood, and Pine (pressure treated). These are also categorized anatomically as softwoods by classification which is distinguished by the fact that they are non-porous. This means that they do not contain vessel elements which transport water in the tree. Softwoods use elongated cells called fibers for fluid transfer.

Rod!~

[MMI Enterprises 289]

hmm..wonder if he was really thinking pore. I for one was just thinking along lines of possable vacant space being able to hold the wood dust or not...interesting topic this hardwood pore thingy :)

[MudDuck 20]

Though I haven't used Ripit before I'm of the understanding that stuff is very strong and harsh. I would think if you put anything that strong on something that didn't have much if anything on it your going to burn it up causing furring. IMO that was your problem. I like HD 80 if I'm going to strip it anyway because I don't think it dives down as deep as say F18 or something in the same strength category. Correct me if I'm wrong please but that is my understanding of it.

I'm suprized no one has mentioned or caught on to him saying he used Ripit on a seemingly bare wood. That would be WAY harsh wouldn't it.

Also I vote osborn brush every time.

[Beth n Rod 1,279]

Yeah, there is a difference between using a hand grenade or a cherry bomb to get the effect (metaphorically speaking of course). Question is, how tailorable in concentration the product is. I have not used it so I am not familiar with its capabilities in this regard.

HD-80 can be mixed weak or strong and I would suspect the same of the Ripit.

Osborns are great at removing the fuzzies but don't help much with the raised grain.

Rod!~

[RPetry 564]

Over the years we have had occasion to use a lot of different NaOH powder strippers, including Rip It, F-18, HD-80, and ACR's 760.

To be honest, I don't think there is much of a difference between them. As Rod mentioned concentration and dwell time, as well as the condition of the wood and old stain, and species of wood, are different when it comes to furring.

Hardwoods in general always come out better with a quick sanding or buffing. Western red cedar often needs defurring, especially if a strong stripper mix was used to remove the old finish. But I cannot remember the last time we had to sand or buff a SYP pressure treated deck after stripping.

[fireandrain 39]

...never worked with a redwood deck that didn't require defurring post strip. Worked with all of the popular strippers, IMHO, no measurable differences. I prefer F-18 myself.