Replies

1. 
   gofigure57 | Mar 23, 2009 03:48am | #1

   Zolton,  Is your hvlp a conversion type or turbine?

1. 
   zolton | Mar 23, 2009 03:55am | #3

   It's a turbine...If you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

2. 
   Samson | Mar 23, 2009 03:51am | #2

   Do you have a water trap in your spray line? If not, you may well have had humidity form the air or condensation from the tank get into the stream when you sprayed the shellac.

   Just a thought.

1. 
   zolton | Mar 23, 2009 03:58am | #4

   Samson,

   My HVLP has its own turbine, so I don't there was water getting into the finish. And I've sprayed a ton of shellac with this thing before and never had a problem.

   The perplexing thing to me is that right after the finish was applied, and a few days later when I was assembling the shelving units, everything looked great. No signs of the blooming or haze anywhere. It was only after sitting in my shop for that three weeks that the problem developed under the layer of dust that had settled on the shelves.

   Thanks for your thoughts... ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

1. 
   SteveSchoene | Mar 23, 2009 04:11am | #5

   I'm perplexed as well.  You speak of dust in the shop.  Was it from anything in particular--a specific material or wood?  Have you treated it as you might treat a moisture issue, by wiping with a damp (not wet) DNA cloth.  I don't know why you would have a moisture haze though, but that's an easy thing to try. 

   Can I assume that the stain was able to achieve the dark color without leaving excess on the surface that might have had curing problems?   Clear shellac has been bleached chemically so may also have a different reaction with less than fully cured stain.  This is just guess work on my part. 

   Edited 3/22/2009 10:08 pm ET by SteveSchoene

1. 
   zolton | Mar 23, 2009 04:19am | #7

   Steve,

   The dust was just general shop dust that didn't get sucked up by my cyclone, and there was probably some shellac dust as well, as I sprayed a few other projects while the shelves were sitting there awaiting installation.

   I haven't wiped the shelves with DNA. I've read that that's the thing to try first. That's what I'll try tomorrow. But the shellac actually seems damaged, and the stain looks as though it has turned a few lighter shades under it. Or maybe that's just the effect of the haze. I hope.

   I'll give it a shot tomorrow and report back. And man, I've really got my fingers crossed! It would be a financial disaster if I had to strip the finish or rebuild them. Days of work and/or hundreds of dollars of materials..

   Zolton

    If you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

2. 
   Samson | Mar 23, 2009 04:14am | #6

   http://www.craftsman-style.info/finishing/048m-varnish.htm

1. 
   zolton | Mar 23, 2009 04:21am | #8

   Samson,

    Yep, I just read this. That's where I learned that the blooming might be cured by wiping or brushing on a coat of denatured alcohol. I'll try that tomorrow, first thing - hopefully before my client arrives...

   ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

1. 
   SteveSchoene | Mar 23, 2009 05:03am | #9

   Brushing DNA is likely to be too much.  Just "healthy dog nose" damp, with several passes, separated by enough time that there isn't time for the DNA to start to "rumple" the shellac.  If you feel any drag STOP. 

2. 
   Joe Sullivan | Mar 23, 2009 07:55am | #11

   Steve is right.  Dog nose damp, and move the cloth rapidly.  You want to lay down a very little -- less than you might ikmagine.  Then let is sit a few minutes and do it again.

3. 
   flairwoodworks | Mar 23, 2009 06:41am | #10

   Any chance that the shellac was drying before or as it hit the wood? It sounds like you are looking at the same thing I was on my first spray attempt with lacquer. I knew absolutely nothing about spraying, other than where the front of the gun was and how to squeeze the trigger. It went on well and looked good. The next day... different story. It had white specks everywhere, sort of like a heavy dust that could be wiped off with my finger. I sanded off the white powder, then brushed on lacquer. Looks great.

   Chris @ www.flairwoodwork.spaces.live.com
   (soon to be www.flairwoodworks.com)

    - Success is not the key to happiness.  Happiness is the key to success.  If you love what you are doing, you will be successful. - Albert Schweitzer

1. 
   zolton | Mar 23, 2009 02:09pm | #12

   Chris,

   Thanks for your reply on the shellac blooming question.

   I don't think it had to do with the shellac drying before it hit the surface. As I said, the panels looked great in the days before I assembled the units. It was only after the assembled units had sat around the shop for three weeks that the blooming started to appear.

   My current theory, thanks to my wife's input, is that maybe some humid air got into the shop and condensed on the shelves. The dust that had accumulated may have held it there until it damaged the finish. In thinking back, I do recall opening up the windows and overhead door for a couple of hours one day in order to air things out and introduce warm air.

   I'd have thought I'd have noticed some condensation or light rust on my cast iron machinery though. But, maybe because I keep all the exposed iron waxed, that wasn't an issue.

   I'm just champing at the bit to get into this storefront so I can try out the "dog-nose damp" wiping technique. I'll report back later - hopefully with good news about the outcome...

   ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

1. 
   Gretchen | Mar 23, 2009 03:53pm | #13

   Since it is so uniform it just seems like it should be that the stain wasn't dry enough.Gretchen

1. 
   zolton | Mar 23, 2009 06:00pm | #14

   Well, nothing worked to get rid of the hazing in the shellac.

   I wiped on the alcohol gently, using a barely-damp rag. Nothing changed. I used more alcohol, no change. I rubbed aggressively; nothing. Pouring it right on the surface (on a top shelf that isn't visible) resulted in softening shellac but no change in color.

   Something looks as though it's going on underneath the surface of the shellac. The color of the stain has faded out badly, leaving behind blotchy panels.

   I went to the local paint store where I bought the stain and one of the sales personnel came back to the jobsite with me. She said she'd never seen anything like it before, but surmised that the stain might not have been dry before the shellac went on. This is a little hard to believe, as I did wait at least 24 hours. But maybe the temperature of my shop retarded the drying to the point that 24 hours was not enough.

   Still, it begs the question of why this only seems to be happening on the horizontal shelves and not the uprights or the undersides of the shelves. I took some photos this morning of the situation and will post them later. Right now though I'm headed back down there with card scrapers and sandpaper and masking tape. The shellac has to come off and the process has to start over. The client wants to move in Thursday, so it's going to be a struggle to get this resolved before then. Lots of work ahead of me and nothing to show for it in terms of extra pay. I guess this is one of the character-building jobs. Funny, I thought my character was already fully developed from all those other ones I did in the past...

   ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

1. 
   SteveSchoene | Mar 23, 2009 08:56pm | #15

   It actually may be stain that hasn't cured.  It might have happened on horizontial surfaces if that is where the excess stain wasn't thoroughly wiped off.  Stain usually cures in 24 hours IF it has had all excess thoroughly wiped off.  But if it has been left more heavily coated--as happens sometimes when trying to achieve a dark color from a wiping stain --then it could take quite a bit longer.  Stain has a slow curing binder so that you have sufficient time to work it over the full surface and still have it not set up too much to wipe off all the excess. 

2. 
   zolton | Mar 23, 2009 11:03pm | #16

   Steve,

   Maybe the stain didn't dry in the 24 hours I allotted. But the blooming isn't happening on the underside of the shelves, and I didn't designate which side was which when I was doing the staining and finishing. It also didn't happen on the 80 inch tall uprights, which I had laid down to stain and finish.

   This is a real mystery because, stored in my shop, I had the units standing up so close to one another that some were actually touching. Some dust did filter into the units that were stored toward the middle, but not much. I also question whether there was much air exchange going on while they were stored like this. So that might be a point against humid air condensing on the horizontal surfaces. But the damage gives an indication that that might have been a contributor.

   I emailed both Zinsser and the makers of Old Masters stains, but so far have not received any reply to my query about any theories they might be able to advance about the problem.

   I'm actually just back from the jobsite, where I spent 5 hours scraping and then sanding the shelves. My shoulder is really hurting from reaching into those 16 inch deep cavities. I was also able to restain them this afternoon. I'm letting them dry overnight - maybe more! But the store the shelves are in is much warmer than my shop; they keep it at about 72 degrees. I would think 20 hours of so that much heat would cause the stain to dry..

   Instead of shellac for the top coats, I'm going with Pratt and Lambert #38 alkyd varnish. Better build and wear resistance, and maybe more compatible with the stain?

   ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

3. 
   BMan7418 | Mar 24, 2009 05:04am | #17

   Zolton,

            I bet the reason only the tops have problems is gravity. Everywhere else the stain would have been running away from the wood. While the horizontals the stain would have penetrated deeper into the wood - just deep enough not to completely dry overnight.

   Bryan

    

4. 
   zolton | Mar 24, 2009 05:21am | #18

   Bryan,

   Interesting theory - gravity. I thought at first you were going to say "fear." As in fear kept the stain in the wood rather than running away from it.

   At any rate, I hope to have this job knocked out by Wednesday sometime. It sure would be good to get a definitive answer about why it went bad though.

   ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

5. 
   mcecala | Mar 24, 2009 04:26pm | #19

   Gravity seems to be the mechanism. I think we are all still stumped as to the cause. Every horizontal surface that could receive airborne dust has a problem, is that correct?If that is the case, and the other surfaces are fine, I think BMan7418 has an idea. Weather it is the stain not drying properly, dust, or moisture causing problems, something is different with the horizontal panels. Where do you live, I am in Phoenix, and yes it is dry, but a few damp days could have caused a problem.It seems to me you are proceeding with full refinishing now, so our input will not save any work, just future problems. I really wish I could help on this. I have been in that spot before, sharing your situation will prove to help all of us. Maybe we could pass a hat, buy you a steak dinner?Possibly a test with one horizontal, and 1 vertical panel. Finish like you did the others, and watch the changes daily. You are an experienced craftsman, and this is something that puzzles you, and leaves many of us really perplexed. I like shellac, and use it all the time in different applications, and this confuses me. I think we are all trying to figure out how this happened so we can save a character building experience.

6. 
   zolton | Mar 24, 2009 05:36pm | #22

   Renthal,

   I live in Southwestern Michigan, and it's kind of a damp/humid climate in the summer. But this job was done just a month or so ago when it was still cold out. My shop is heated - although not really to living standards. But I've sprayed a lot of shellac in the cold before and never came across this, or any other, problem.

   I'm starting to think that it does have something to do with the stain and shellac not getting along. The stain may not have been completely dry, although I did allow 24 hours. It just might have been too cold in my shop for it to completely cure. And maybe putting two coats on the top side of the panels and only one on the underside worked to trap the solvent outgassing. All theory at this point.

   I might go back and try a test panel or two, letting the stain dry completely on one and rushing it a bit on the other, just to see if that has any effect..

   ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

7. 
   Biscardi | Mar 27, 2009 03:28am | #51

   Zoltan,

   Do you think wiping the suface with a gel stain would cover the opaque shellac? It might be easier than stripping all the shellac off.

   Frank

8. 
   zolton | Mar 27, 2009 04:57pm | #52

   Frank,

   Too late. I already scraped the shellac and most of the stain off, and redid the job with new stain and two coats of varnish. The owner moved in yesterday and he already is piling the shelves high with fabric samples and books.

   But no, I didn't think of covering the shellac with gel stain. That would have been something to try. I kind of doubt it would have worked very well though. There were portions of the shelves that were still the deep, rich color that they started out with originally, but the middle section was mottled and quite a bit lighter. Covering everything with another coat of stain would only have made the original areas too dark compared to the lighter areas. I guess I could have tried blending a gel stain into the mottled areas, but there were a ton of shelves and not a lot of time to fiddle around with that..

   ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

9. 
   joinerswork | Mar 24, 2009 04:44pm | #20

   Zolton,

   Interesting problem you have been dealing with.  If it were my problem, it wouldn't be as interesting.

   Like others, I'm inclined to guess that the stain was still outgassing when you sprayed the shellac.  But the appearance of the problem on only some of the panels is what makes it "interesting".  Something is different about them.  I doubt the dust is what caused the blushing.  Sunshine maybe?  If the shelves were oriented so that they'd get sun, thru a window, they'd warm up, and maybe that is what caused the stain's solvent to get active on the panels' top surfaces.  Just a guess, but I've had sun- warmed panels do funny things during the finishing process, and bleeding stain that looked dry is one of them.

   Ray

10. 
    zolton | Mar 24, 2009 05:30pm | #21

    Ray,

    Interesting mention of sunlight hitting the panels, because that's exactly what the finish looks like - as though sun had been bleaching them for several years. The color is washed out of the stain under the shellac.

    The surface of the shellac is just fine. It has cured hard and the sheen compared to the rest of the unaffected parts of the panels is also unremarkable. So my feeling is there was something going on between the shellac and stain. But why only in those areas, and only on the horizontal panels, is what is really puzzling.

    In the end, as you said, it might have something to do with the stain either not being fully cured or outgassing, and that somehow affected the shellac/stain interface.

    Both sides of the panels were all stained at the same time though. I first stained one side and then did the other while the first side was resting on a board with nails sticking out of it. I then allowed the panels to dry by resting them on edge on some 2x4's that I had driven spikes halfway into so they could lean over a little bit. There was plenty of air circulation between the panels.

    I first sprayed one coat of shellac on both sides, and then another coat onto the top of the panels that would be facing upward. That's it.

    Right now I've got a headache from this. Not only thinking about it, but also because I've just spent the last two hours with my head stuck inside these shelves brushing on #38 varnish..

    ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

11. 
    cwalvoord | Mar 24, 2009 09:07pm | #27

    So did I read correctly that the problem surfaces all had two coats of shellac and the others got only one? If so then that would seem to be an important clue. Perhaps something was trapped between the two layers (seems unlikely but...) or, as I think you speculated elsewhere, the two coats sealed up the not quite fully cured stain but good and caused the problem where as the one coat was permeable enough to let the stain finish curing.This is a very interesting thread, thanks to all the contributors. I have always thought of shellac as the ultimate no-brainer barrier coat to be inserted anywhere in the finish schedule where there might be compatibility problems. Just goes to show that every step needs to be well thought through and tested.
    Chris

12. 
    zolton | Mar 25, 2009 02:37pm | #32

    Yep, there were two coats on the top side of the shelves, so that might very well be an important clue.

    Your mention of shellac being the ultimate no-brainer barrier coat is always the way I thought of it. But it's proof positive that if there's a way to screw things up, I seem bound and determined to find it!

    ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

13. 
    boilerbay | Mar 24, 2009 05:52pm | #24

    Any thought to sun light hitting the horizontals and thus heating a not quite dried stain under the shellac? It would only affect the tops sides - no?
    Just musing.Boiler

14. 
    zolton | Mar 24, 2009 06:06pm | #26

    Boiler,

    The sun did not hit the shelves, either while the stain was drying or after everything was finished. My shop is dark, with only one, small south-facing window. And the problem showed up on all the horizontal panels, from top to bottom. Sun would not have been able to access all the hidden corners on all the shelves.

    ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

15. 
    GDH2 | Mar 25, 2009 04:29am | #30

    Taking a different tack entirely, blame the customer for not specifying adjustable shelves. Then you could just turn the shelves upside down. My sympathy goes out to you - your methods were well established and professional. Sometimes bad stuff happens. I sure would like to learn what happened (add to the post even a year from now if you figure it out). In the meantime, Thursday keeps getting closer! Good luck!
    Doug
    The Wood Loon
    Acton, MA

16. 
    Ron01960 | Mar 25, 2009 06:48am | #31

    I would call the Zinzer and the stain company technical line. There more than willing to assist you. My senses tell me not enough time span for the temperature in your workshop. Some thing in the stain hasn't cured or evaporated fully, the shellac is sealing off the evaporation process. best fortunes with the problem.Ron

17. 
    zolton | Mar 25, 2009 03:02pm | #36

    Ron,

    My very first inclination was to get in touch with the Zinsser and Old Masters (the brand of stain I used) technical service departments. Unfortunately, they were both closed when I called, so I sent them emails describing the problem.

    Neither has contacted me. In my experience, contacting company technical service via email is a real hit-or-miss proposition. Some get back to you in a timely fashion with good advice. Some send a canned answer that has nothing whatsoever to do with the problem you asked about. And some just don't bother to answer at all.

    It would probably be better if I called and tried to speak to someone in person. But it's hard for me to find the time to do that during the hours they're open..

    Zolton If you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

18. 
    Jfrostjr | Mar 25, 2009 05:32pm | #37

    Zolton,I just caught up with this post. Mowhawk makes a spray-can "Super Blush Retarder". It contains "esters and glycol ethers". (This may enlighten you, but it does nothing for me.) I've used it on lacquers and it works great; don't know about shellac.Good Luck.Frosty"I sometimes think we consider the good fortune of the early bird and overlook the bad fortune of the early worm." FDR - 1922

19. 
    zolton | Mar 25, 2009 08:11pm | #38

    Here are some photos of the shelves in question. They give some indication of how the color had radically changed under the shellac. Note how the mottling stops short of the upright sides of the units.

    Bear in mind, too, that the top surface of the shellac was unaffected by the discoloration going on below. Weird, eh?

    View Image

     

    View Image

     

    View Image

     

    View ImageIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

    
20. 
    PCM | Mar 26, 2009 04:32am | #41

    I've been following this discussion because I have experienced shellac blush and lacquer blush. These pics do not look like the shellac blush I have experienced, although it might be the lighting.

    I have to agree with the theory of stain not properly dried, or some other reaction between stain and shellac.

    A silver lining, as you have mentioned, is the fact the int. designer appreciates you had a problem and will fix it. In his line of work I am sure he has had problems with fabrics not being true to the samples, customers who change their minds, etc.

    Let us know how your repairs worked.

    Pete

21. 
    zolton | Mar 25, 2009 08:14pm | #39

    Frosty,

    I'd have had to order a case of that blushing stuff!

    It doesn't appear to have been a shellac problem. I wiped the surfaces with denatured alcohol and that did nothing at all. So there was something going on between the shellac and stain. Probably, as many have suggested, that the stain hadn't fully cured before the top coats of shellac went on..

    ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

22. 
    BossCrunk | Mar 25, 2009 09:05pm | #40

    Water based dye stain.

23. 
    KiddervilleAcres | Mar 26, 2009 04:02pm | #42

    But why just parts of the boards, primarily the middle?  Looks like the ends were ok or am I seeing it wrong?

    Heads up show Zolton.  That's real ethic and will do you well in the future.

    Regards,Bob @ Kidderville Acres

    A Woodworkers mind should be the sharpest tool in the shop!

24. 
    zolton | Mar 26, 2009 04:23pm | #43

    Bob,

     I learned a really good lesson years ago about how to deal with customers from a friend named John Bright. John was a man who owned a printing company, and I happened to be doing some carpentry work for him one day in his office.  

    One of John's client came in; someone from the local chapter of the American Kennel Club. The client was having some certificates printed up, and he asked John if he had someone who could hand-write the dog's names on the certificates using calligraphy. John said, "Sure. I'll do that for you."

    After the client left I asked John if he had someone on staff who did calligraphy work. John said no, but that he would find someone who could do it and hire that person for the job. He went on to say that the customer didn't want to hear "no, you'll have to get that done somewhere else;" he was looking for a one-stop, turnkey solution to his needs. And John said he was willing to provide that service.

    I learned a valuable lesson that day. And since, whenever something like what happened to the finish on those shelves occurs, I look at it from the customer's point of view. My client didn't want to hear me whining about a finish failure. He had hired me to build and install shelves for him. And that's what I did.

    Because of the finish problems, it took way longer than it should have, and I made much less per hour than I had been planning on. But that wasn't my client's fault. He had enough stresses to worry about packing up and preparing for the move into his new office space. I didn't want to add to that the problems I was facing. So I just did what needed to be done.

    Interesting side note: This all happened in a very old building in the downtown area. A remodeling company had been doing renovations in the storefront since October, and they were finishing up work when I arrived with the shelving. Let's just say that they work at a different pace than what I'm used to. There was a lot of standing around and talking, taking breaks, drinking coffee and eating doughnuts, whereas I was there to work every moment until I got finished. It might be the difference between being an employee and someone who owns his own business.

    At any rate, when it came out that the finish on the shelves was defective, the crew on site really talked up to my client the way I attacked the problem. They said they were mightily impressed at all I did to rectify the situation. Of course, anyone moving at more than a snail's pace would look like he's doing more than those guys were. But it doesn't hurt to have that type of thing added to your reputation with a client....

    Zolton If you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

25. 
    BossCrunk | Mar 26, 2009 07:15pm | #44

    Not to minimize your obviously very high business ethics, it would frankly be hard for the worst, slap-it-together craftsman to wriggle out of a fix for the debacle in your photographs.That's one you couldn't possibly have hidden from. In a million years.

26. 
    zolton | Mar 26, 2009 07:43pm | #47

    You're probably right in that I couldn't have "hidden" the debacle from the discoloration on the shelves. But the client didn't think it was that bad. His opinion was that the shelves were going to be hidden with stored items anyway, so it didn't matter all that much - as long as the affected areas didn't show decreased resistance to wear.

    The photos did highlight the damage a bit more than what was actually visible. It was pretty bad, but not quite as dramatic as the images showed.

    ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

27. 
    Gretchen | Mar 26, 2009 10:47pm | #49

    For what it is worth, I never ever saw any glimmer that you weren't going to make this "right".Gretchen

28. 
    zolton | Mar 26, 2009 11:49pm | #50

    Gretchen,

    Yeah, it's kind of an obsession with me. I don't like having my name associated with things that aren't complete or done right.

    ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

29. 
    dkellernc | Mar 26, 2009 07:23pm | #45

    Zolton - I suspect those that have suggested (and you've suspected) insufficient dry time between application of the stain and the application of shellac are probably correct.

    However, I've another possibility.  I ran into this while helping a friend on his own WW project - a set of inexpensive utility shelves for his kid's playroom.  They were made of plywood from the Home Despot, with solid-wood edging.  The finish was a one-step Minwax poly and stain (not my choice, but it was his project). 

    The finish bubbled really badly about 2 days after application, and it wasn't air bubbles from the application - this was de-lamination from the surface of the plywood.

    The diagnostic for the problem was that I'd given him a partial sheet of oak ply that I'd had in my shop for about 2 years.  The portions of the project that contained this did not bubble or de-laminate, but the Borg plywood did.  My educated guess is that the problem was actually caused by out-gassing from the plywood itself.  It's the only time I've ever encountered something like this, but I have talked to people in the local WW club that have experienced something similar.  As you might expect, this was Chinese-made Borg plywood, so I do wonder what they were using for glues when the ply was manufactured.

    This might fit with your pictures - potentially, the plywood didn't cause the finsih to blush near the end cuts because these would presumably out-gas much faster than the centers of the panels.

    This is, of course, a rather wildly speculative idea, but I thought I'd mention my friend's experience in case it was pertinent (the end result in his case was similar to yours - lots of sanding, a primer coat of Kilz, and latex paint).

30. 
    zolton | Mar 26, 2009 07:39pm | #46

    DK,

    A very interesting report about the outgassing plywood in your friend's project. That did occur to me too at first. The theory about the outgassing being trapped in the main body of the panel rather than at the edges, where it could leak out faster, is certainly a possibility. Geez, so many ways for a job to fail!

    I'm planning on doing a test of all the materials involved when I can get back into my shop next week, maybe setting up a "scientific" experiment to first stain several pieces of the plywood and then coat them with shellac at various intervals - say 4 hours, 8, 12 and 24, to see if I can reproduce the deterioration and discoloration. I'll report back here when I can see some results...

    ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

31. 
    BossCrunk | Mar 26, 2009 08:07pm | #48

    Uneven drying/curing of the petroleum based stain - could have been as simple as the way the air moved over or through or swirled in the case itself.

32. 
    zolton | Mar 25, 2009 02:55pm | #35

    Doug,

    Thanks for the encouraging words. This was a very bad thing to happen and I still don't know the exact cause, though many others have said that the stain maybe wasn't fully cured before the shellac went on. And that's the way I'm leaning too.

    The important thing is that I was able to deal with it to the satisfaction of my client. In the end it's going to take about another ten hours on a job that had an original time budget of 40. But that's the way the cookie bounces sometimes. As my track coach once said, "Sometimes you get the bear, and sometimes the bear gets you."

    On Monday I scraped off all the shellac and most of the stain from the shelves (30 of them, 32 inches by 16 inches), sanded them smooth and then restained them. Yesterday I put the first coat of Pratt and Lambert #38 varnish on, and this morning I'm headed back down there to sand the first coat and put the final one on. Then I can send my bill. I'll make about eight bucks an hour, but that's still better than minimum wage, isn't it? Those bear claws do hurt though!

    The most gratifying thing to come out of this is that my client is pleased with the way I handled it. I informed him right away that there was a problem. And after getting the local professional paint store's advice on it (and the advice of Knotters too), I went right to work at fixing it. I kept him informed of the process, and he went over to check it out yesterday. I was away visiting the grandkids at night when he left a message on my answering machine saying that he was very pleased with how things were turning out, and that the shelving "exceeded my (his) expectations." So, dealing with it like this was important from a customer relations standpoint. And, because this client is an interior designer, it could be that I get some work for him in the future.

    Sometimes you've just got to keep your head up and continue to plow forward.

    ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

4. 
   TdeKorte | Mar 24, 2009 05:47pm | #23

   Zolton,

   I hope you were able to correct the problem.  As to the problem: I think it may have occurred because of the stain not being fully cured.  Taking the color from birch to a walnut look might mean that the stain had to be laid on fairly heavy. 

   You didn't mention if you gave the shellac a " drink " of DNA before spraying, nevertheless HVLP units are capable of laying down a good heavy coat due to the transfer efficiency they have. ( especially when spayed on a horizontal surface )

   I suspect the entrapped solvent in the shellac coat worked on the stain while the unit sat in your shop.  The weird thing is that a DNA wipe down should have corrected the problem if it was in the shellac.  So this would lead to the conclusion that the solvents in the stain reacted with the shellac......  Bummer..

1. 
   zolton | Mar 24, 2009 06:04pm | #25

   I didn't thin the shellac, if that's what you were asking. At a 3 lb cut right out of the can I've never seen the need to do that.

   I am starting to think, however, that the stain might not have been cured fully, and that encasing it in two coats of shellac might have set off the reaction..

   ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

1. 
   Joe Sullivan | Mar 24, 2009 09:15pm | #28

   Zolton:You are likely on to something when you suggest the thickness of the shellac may have caused a problem with out-gassing. A couple of coats of 3# pretty much seals anything up tightly. It is a near perfect water vapor barrier, for example.About four years ago I used shellac to refinish a large oak floor on slab. I use shellac all the time, and have a fair amount of experience with it on floors. Nevertheless, the old finish was pretty worn, and there were minor signs that through-slab moisture was present. The floor had been in place for 16 years with minimal problems. Within three weeks of being sealed up with the new shellac, it buckled. Within a few months, the buckling was up to about 4 inches. When I pulled up the floor and replaced it, there was no trace of liquid water under the wood.Sometimes, it is just TOO good a sealant.Joe

1. 
   zolton | Mar 25, 2009 02:41pm | #33

   Joe,

   Very interesting experience with that floor! It must have broken your heart to see it buckled up like that. I've only seen buckling that bad a couple times in houses where pipes burst and flooded everything.

   I do think that the fact that shellac is such a good barrier coat has something to do with the problem I experienced. As time goes on I'm thinking more and more that the shellac maybe sealed in the outgassing of the stain, or that the stain wasn't fully cured.

   Thanks for your input..

   ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon

2. 
   sapwood | Mar 25, 2009 12:21am | #29

   Another wild thought: Are you sure that it didn't happen on the vertical panels? Could it be a reflected light issue and just doesn't show up except on the horizontals?

1. 
   zolton | Mar 25, 2009 02:44pm | #34

   Sap,

   It's pretty obvious when the mottling does occur. I examined each panel very carefully, and it does appear primarily on the horizontal panels. There are a very few, very minor spots where it appears on the vertical panels. But nothing like what happened on the horizontal ones.

   The vertical uprights were finished at a different time than were the shelves. So maybe I inadvertantly allowed the shelves to dry for a shorter time than I did the uprights.

   ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon