Black spots following stain application

[Stan Forston]

I'm looking for advice on what causes tiny black spots to appear on curly maple following application of ColorTone liquid stain (water as solvent; light colors such as yellow, amber, etc.). They don't appear immediately and I am certain that I didn't drip any dark stain on the wood. I used distilled water with the stain on bare wood. I can usually sand out the spots, but I'm concerned that at some point, they will penetrate deeply enough to completely ruin the finish. I used no steel wool that could have rusted. Some of the spots appear as tiny "spidery" patterns. Attached is a photo of one of my test pieces using off-the-shelf curly maple from the local woodworking store. Thanks for any suggestions.

Stan Forston

[Chuck Tweedy]

Must be iron. The picture looks like the points of a staple that was in the wood.

[Stan Forston]

Thanks, Chuck. I thought about iron deposits, but I've had this happen to several different pieces of maple, some of which are years older than the others. The spots very in size from pinpoint to a few mm in width and do not appear immediately after the application. It does seem as if there is some chemical reaction occuring - I've also considered other mineral/metallic reactions with the water or the stain, but it only manifests as one to three spots, not something that occurs across the entire surface. I've received advice about wash coating with shellac, then mixing the stain with shellac for application. I tried that and no spots appeared, but the color was very hard to manage with shellac-based stain over the wash coat - lots of streaking as the stain seemed to slide over the washcoat as opposed to soaking in and blending the application strokes.

[Chuck Tweedy]

Colortone liquid stain is miscible with alcohol. So, dilute it directly in alcohol, and apply it directly to the wood as you would with water. That minimizes the water that goes on the wood. Then, when you have the color you want, wash coat with shellac to seal in the color, and you can apply waterborne finish over that. Still, no water on the wood.
Sorry, I'm not helping with diagnosing the problem, just brainstorming a way to avoid the problem.

[Todd Stock]

If iron staining, oxalic acid will remove - maybe try that and see if culprit is Fe.

[Stan Forston]

Thanks, Chuck and Todd. I'll give both suggestions a try.

[Brian Evans]

When I stain I do a wash coat with 1# cut dewaxed shellac and use an alcohol based stain. It seems like the wash coat limits blotching but the alcohol base of the stain grabs and helps make an even application.

[David King]

I've never been pleased with any stain job I've ever done, especially over figured maple.

[Eric Knapp]

I've never been pleased with any stain job I've ever done, especially over figured maple.

That's quite quotable. I found that to be true in my furniture days. I liked dyes a little better but eventually stopped using them all. I suspect I will stay that way with guitars. I like wood just the way it is.

-Eric

[Barry Daniels]

Spraying toner coats with a bit of dye is the best way to treat figured maple in my opinion.

[Todd Stock]

Epoxy or shellac, then toner over a sealer coat...pops curl with higher index material (epoxy and shellac are very close in refractive index...around 1.5 or a little more) and keeps dye from soaking into wood.

[Randolph Rhett]

I think dye on wood can work quite well if you are going for very dark. If you just want a slight amber glow and some figure pop what the other said about dye in your first coats of finish is probably the ticket.

[Stan Forston]

Great advice, all. Thank you. I'm not happy with the stain so I'll try the strategies suggested. My first (archtop) I finished with a French polish and that worked pretty well. Thought I would try adding some color this time, so that's where the stain story starts.

[Alain Lambert]

Something similar happened to me before.
I was refinishing a stair case (don't remember if it was maple or oak), and I used scrapers to remove the old finish. I was sharpening the scrapers often. The day after I applied my first coat of waterbase finish, I had tiny dark spots all over. These were from the tiny filings that were on the scraper edge! I had to sand back and start over again!

[Jason Rodgers]

Something similar happened to me before.
I was refinishing a stair case (don't remember if it was maple or oak), and I used scrapers to remove the old finish. I was sharpening the scrapers often. The day after I applied my first coat of waterbase finish, I had tiny dark spots all over. These were from the tiny filings that were on the scraper edge! I had to sand back and start over again!

I bet until this happens to you, one would never suspect the scrapers!

[Stan Forston]

Whoa! Great thought. I did a lot of scraping prior to final sanding - I guess a healthy blast from an air compressor would help. Any other way to assure no filings are left behind? Is a magnet a potential solution? Seems like there's some risk of filings regardless of how the wood is prepped.

[Barry Daniels]

A quick wipe with an old fashioned Tack Rag is a good thing to use just before the first coat of finish.

[Todd Stock]

Back when we scraped teak decks to get them back into shape (before ROS and other modern convenances), we'd sharpen scrapers over the side...and run one of those big yard magnets over the decks before the dew fell...not unusual to come back next day and find little black spots if we missed a spot. Got to hate doing decks, but good at sharpening scrapers.