New guy needs help with mahogany.

[Mike Saffold]

Hello everyone. I've been a reader of these forums for over a year and thanks too all the good information on tool selection and shop set up. I have finally built my first piece of actual furniture. Or so I thought. As you all know and I recently found out. finishing is just as important as the actual construction. Unfortunately the arcane art of finishing seems to be much more complex. I have researched all over the net. Have bought several books on finishing, heck I even read a few of them, and now I at least have some idea of how much I don't know.
If I knew then what I know now (which ain't a lot) I don't think I would have strapped on my respirator and brushed the Potassium Dichromate onto my beautiful though obviously flawed painstakingly crafted Mahogany breakfast bar.

Here's where I could use some help. I built a curved mahogany breakfast bar top and decided to use Potassium Dichromate to color the wood and it looked good. I then decided to go for a mirror gloss and hard finish. Based on all the research I did , most of the good info I found came from this website so thanks again, I chose to fill the pores with Behlen water based filler and I plan to finish with Behlen Rockhard varnish. After coloring with the Potassium Dichromate I applied a 50% thinned seal-coat of the varnish and then the filler. Here's my problem; in sanding off the filler I have sanded through the coloring in places.
My question is; what to do next? Should I attempt to "touch up" the light areas with more Potassium Dichromate? Would that react strangely with the sealed and filled wood? Should I now use some other staining technique? Should I burn the whole damn thing in a fire, which is what I wanted to do after a wiped of the dust from sanding the filler and saw what had happened to the color. By the way. Yes, now I know I should have tried out my finishing schedule on a scrap of the mahogany. Lesson learned the hard way.
Any help would be very much appreciated.

Mike Saffold
Tampa FL

[John Harden]

Hello everyone. I've been a reader of these forums for over a year and thanks too all the good information on tool selection and shop set up. I have finally built my first piece of actual furniture. Or so I thought. As you all know and I recently found out. finishing is just as important as the actual construction. Unfortunately the arcane art of finishing seems to be much more complex. I have researched all over the net. Have bought several books on finishing, heck I even read a few of them, and now I at least have some idea of how much I don't know.
If I knew then what I know now (which ain't a lot) I don't think I would have strapped on my respirator and brushed the Potassium Dichromate onto my beautiful though obviously flawed painstakingly crafted Mahogany breakfast bar.

Here's where I could use some help. I built a curved mahogany breakfast bar top and decided to use Potassium Dichromate to color the wood and it looked good. I then decided to go for a mirror gloss and hard finish. Based on all the research I did , most of the good info I found came from this website so thanks again, I chose to fill the pores with Behlen water based filler and I plan to finish with Behlen Rockhard varnish. After coloring with the Potassium Dichromate I applied a 50% thinned seal-coat of the varnish and then the filler. Here's my problem; in sanding off the filler I have sanded through the coloring in places.
My question is; what to do next? Should I attempt to "touch up" the light areas with more Potassium Dichromate? Would that react strangely with the sealed and filled wood? Should I now use some other staining technique? Should I burn the whole damn thing in a fire, which is what I wanted to do after a wiped of the dust from sanding the filler and saw what had happened to the color. By the way. Yes, now I know I should have tried out my finishing schedule on a scrap of the mahogany. Lesson learned the hard way.
Any help would be very much appreciated.

Mike Saffold
Tampa FL

I know it can be frustrating, but hang in there. The seal coat you applied is what makes it tricky. If you tried to apply more PD over it to touch up the light areas, it won't likely penetrate the varnish.

Perhaps the best advice I can give you would be to call Behlen's. My guess is their technical people have heard it all and would be able to advise you how their product will react with PD.

If they don't know, you could always duplicate what you've already done on some scrap, then try it out on there. Just use a large enough piece of scrap that you can get a real feel for what your touch up attempts actually look like.

Another option would be to try to sand or scrape off the seal coat from the whole table and hit it with PD again. Trouble with this approach is you say that when you hand sand the filler, you're removing the PD coloring causing blotchiness. The real question is how successful will you be touching up the PD coloring?

Absolute worst case is you sand off the seal coat, AND most all the PD coloring and hit the whole surface with PD again. Basically start over.

You might try the Greene & Greene yahoo forum. Lot's of people there with tons of experience using PD on mahogany with and without wood fillers. I'm sure they'll give you better advice than I can.

Regards,

John

[Mike Saffold]

John,
Thanks those are several good ideas. I will try to call Behlen, although for some reason I think they are in England. I don't know why it didn't occur to me that I could still use the scrap technique, retroactively so to speak. Also, I'll check out the forum you mentioned,

Thanks!!

[John Harden]

One other thing. Are you certain that you actually sanded down into the PD deep enough to change its color? PD generally goes fairly deep into the wood.

Is it possible that what you're seeing is the light colored grain filler being smeared around the table top and sitting on top of the surface?

You might try hitting it with some mineral spirits and cleaning off a section to see what this does. It won't harm the PD, but will help remove any leftover grain filler that is hanging around.

Regards,

John

[Jeff Monson]

One other thing. Are you certain that you actually sanded down into the PD deep enough to change its color? PD generally goes fairly deep into the wood.

Is it possible that what you're seeing is the light colored grain filler being smeared around the table top and sitting on top of the surface?

You might try hitting it with some mineral spirits and cleaning off a section to see what this does. It won't harm the PD, but will help remove any leftover grain filler that is hanging around.

Regards,

John

Thats a great point John, I just did a desk and used PD for a darkener, on my sample boards it penetrated the mohagany a long way.

[george wilson]

I want to tell you from personal experience that Rock Hard varnish isn't very hard at all. I used to know a chemist at Behlen,and called him to ask why it was so soft. He told me they named it that because it is alcohol resistant. Still makes no sense to me.

I used some gel polyurethane on my upstairs floor,and it is REAL hard.

[David Winer]

For some reason, I feel your pain. Never have been in your exact situation, but have waded into finishing problems. You may have gotten into such a complicated salvaging operation that starting over would be simpler and more reliable. Think about sanding down to bare wood, then follow your improved finishing procedure. After all, you now know the pitfalls.

[John Harden]

I want to tell you from personal experience that Rock Hard varnish isn't very hard at all. I used to know a chemist at Behlen,and called him to ask why it was so soft. He told me they named it that because it is alcohol resistant. Still makes no sense to me.

I used some gel polyurethane on my upstairs floor,and it is REAL hard.

That's interesting. I didn't know that about Rock Hard varnish.

Personally, I prefer Waterlox original for table tops. Works well for me on everything from my work bench to wood floors. Best thing of all is it is easily repairable. Scuff sand and reapply, whether its a small surface repair, or the entire top.

I'm making a mahogany dining room table and will be using Waterlox as the surface finish.

Regards,

John

[Frank Drew]

"I will try to call Behlen, although for some reason I think they are in England."

I thought Behlen (Mohawk) was in upstate New York; have they moved?

In my experience, each application of potassium dichromate darkens the wood further, so use a light touch and maybe start filling in the light spots with a dilute mix.

[Paul Saffold]

Mike. welcome to the creek. I hope you will show us a picture of your work.

I'm hoping that you (and others) are aware of the hazards of working with potassium dichromate. Sanding dust of PD treated wood is also hazardous. Lots of good info available on the web for anyone interested. I'm not trying to preach, but it's not a chemical that I would have in the house and risk exposing to other family members, especially youngsters.



Paul

[Mike Saffold]

Paul,
Your point about the potential dangers of PD is well taken. Here's the deal; I know it might sound stupid but, I got interested in wood working from watching the tv show "Woodworks" with David Marks. He used it and it looked great. When you know nothing about out a subject anything can sound like a good idea. Chemically altering the color of the wood to achieve a rich even appearance, Cool! why not? When I get into a new activity I generally try to stick with conventional knowledge at least initially. Instead, for my first project I have created a Frankenstein situation that no one can really offer advice on how to fix. And, oh yeah by the way it could cause cancer. I was very cautious applying the chemical but never even considered the sawdust. WOW!

Been stewing about this all day and half the night. Still not sure what to do next. I know I'm not going to sand it all back and start over, thereby filling my garage with poison sawdust. I'm thinking I will just leave the light areas, these are only on a few edges btw, and completely encase this biohazardous quagmire with as much rock-hard varnish as I can and call it a day.

If this project cant be a shining example, maybe it can serve as a cautionary tale.

[Jeff Monson]

Mike, I would think you have nothing to loose by trying to apply some PD to the lighter spots, it cant hurt anything that I can think of. I might opt to try to dilute the PD a little more than the 1st time, so you dont end up with darker spots, the wash coat should prevent the PD from contacting any other wood correct?

[Mike Saffold]

Jeff,
That's actually what I finally decided to do, or at least try to do. First I created a test board. So, I had to follow the steps that got me to where I am now. I'm literally about to go mix up some more toxin to see how it will work on the sanded through areas.

[Chris Fitzpatrick]

Hello Mike, I 've had problems like this, though not with PD, I just sanded it all off. It is frustrating, but also encouraging when you see it done the way you want. For what it's worth, I've used Behlen oil based grain filler and had good results on mahogany. Used burlap to clean it off after it hazed. I use a 1lb cut of shellac for a wash coat and find that works well. Good luck

Chris

[David Cefai]

If you have to remove the finish and are worried about the PD, couldn't you use a card scraper?

The stuff will come off in lovely thin shavings with little, if any,dust.