Finishing problems

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Blog entry by Tim Suess posted 06-02-2009 08:44 PM 1049 reads 0 times favorited 15 comments Add to Favorites Watch

I am hoping someone can help me with this. Recently when I have been finishing my projects I have noticed little black spots form on the wood. I figure it was mold that had grown on the wood since my shop in our basement. So the next time I finished a project I put the dehumidifier in the room and used wood fresh from the lumber yard. The same thing happened!!! Does anyone know what this is or have run into it before?

-- T. Suess

15 comments so far

View teenagewoodworker's profile


2727 posts in 3185 days

#1 posted 06-02-2009 09:27 PM

probably fish eye. some sort of grease or something getting on your project. wipe it down with naptha before finishing

View Todd A. Clippinger's profile

Todd A. Clippinger

8901 posts in 3516 days

#2 posted 06-02-2009 09:33 PM

What is the finish and what is the wood?

-- Todd A. Clippinger, Montana,

View Damian Penney's profile

Damian Penney

1141 posts in 3408 days

#3 posted 06-02-2009 09:50 PM

If you are using wire wool it could be rust.

-- I am always doing that which I can not do, in order that I may learn how to do it. - Pablo Picasso

View Tim Suess's profile

Tim Suess

12 posts in 3123 days

#4 posted 06-02-2009 10:27 PM

I am using water based poly which I have used in the past with no problems, on various types of wood, oak cedar pine maple etc.

-- T. Suess

View kolwdwrkr's profile


2821 posts in 3007 days

#5 posted 06-02-2009 10:41 PM

have you sprayed anything else out of the gun other then finish?

-- ~ Inspiring those who inspire me ~

View Milo's profile


869 posts in 2736 days

#6 posted 06-02-2009 11:02 PM


I doubt it’s fisheye (sorry Teenage), because you don’t mention any divits in the finish. Kolwdwrkr might be on to something, but I was wondering how old you finish is. Water based can crap out on you due to age and contamination, so you may want to look into those things.

Also, you are filtering the finish before you use it? Are you cutting it with DI water only?

Just some thoughts. I’ve screwed up for finishes than I’ve aced. ;-)

-- Beer, Beer, Thank God for Beer. It's my way of keeping my mind fresh and clear...

View Kjuly's profile


306 posts in 2702 days

#7 posted 06-03-2009 12:45 AM

Could you post a picture?
Did you use a wood stain?
Was the problem on Red Oak?
Sorry to answer a question with a question but I think a little more information could help sort out the problem.

-- Keith, Charlotte, MI

View Luke's profile


545 posts in 2711 days

#8 posted 06-03-2009 02:42 AM

You didn’t say if you were using a spray gun or not right? gotta have more info, yeah

-- LAS,

View cabinetmaster's profile


10874 posts in 2975 days

#9 posted 06-03-2009 03:02 AM

I agree with all that has been said. Show us a picture with a little more detail and we can probably give you some very good answers.

-- Jerry--A man can never have enough tools or clamps

View teenagewoodworker's profile


2727 posts in 3185 days

#10 posted 06-03-2009 03:21 AM

yea. i didnt know it was water based so it could be rust or plenty of other things. if it is sprayed it could be other things to but i assumed it was wiped. we probably need more info

View a1Jim's profile


115166 posts in 2994 days

#11 posted 06-03-2009 03:35 AM

I would guess if you used water base and steel wool it’s rust spots or it will be. You never use steel wool on water base products together. If that’s the case all you can do is sand off the poly and clean with naphtha and re coat, and if you want a second coat use 600-1200 grit sand paper in stead of steel wool between coats.

-- Custom furniture

View Tim Suess's profile

Tim Suess

12 posts in 3123 days

#12 posted 06-03-2009 04:28 AM

Ok, I am using water based poly from General Finishes, I bought it at woodcraft and I tinted it with transtint dye. I have done this process before with no spots. I am brushing the finish on with a new brush/rag and I have used and not used steel wool and the same thing happens. Ill try to get a picture up but they look like mold. they are about 1/16 to 1/8 inches in diameter and gray to black in color. I have not used a wood sealer or napatha before finishing which is probably my fault/problem but like i said I have done this same process before with no spots.

-- T. Suess

View Jon3's profile


494 posts in 3522 days

#13 posted 06-04-2009 08:48 PM

I don’t know about the GF poly, but Transtint specifically says not to use it with 2 part poly, because it won’t completely blend.

Also, since you’re using a WB poly, you have to take the same care with Transtint that you do when using it with water. If there’s any kind of contamination, you’ll get grey spotches.

See here for more information, including what sounds like an exact description of your problem!

View blackcherry's profile


3292 posts in 3240 days

#14 posted 06-05-2009 04:34 AM

It the dye it not compatible with the water base varnish, the dye will not disperse or blend evenly with the finish. Jon 3 is correct in his observation. Some tint have more gut or natural earth material and will not blend as some are light in color and have no problem with blending into the medium in this case water base poly. ....take care and enjoy your future works….Blkcherry

View FredG's profile


140 posts in 3114 days

#15 posted 06-05-2009 06:10 AM

You might try to add a few drops of an ox gall solution.
This will give you a better mix. It will lower the surface tension.

1 teaspoon of ox gall powder
100 cc alcohol (96 %)

Allow to stand for 3 days.

-- Fred

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