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Blog entry by monkeyman83 posted 01-23-2017 02:56 PM 649 reads 0 times favorited 6 comments Add to Favorites Watch

A friend of mine is working on a bed for his niece. He has been running into issues that I am going to share with the community. I want to give him some advice, but I want to make sure I am giving him the right advice. Below is the message that he sent me. Any advice the community can provide will be greatly appreciated. Thanks.

I made a bed for my niece out of red oak plywood, and trimmed it in solid red oak. I put a 1/4” rounded bead on all from facing edges. Prior to assembly, and again after I sanded to 150 grit ensuring all surfaces felt the same and then used a TON of 100# air to make sure I got all the dust off.
I’m using minwax ebony color stain and applying this in the house so the temperature stays relatively constant. I also ensured I wiped off the excess stain before I was done. I put one coat on the entire project and felt a second was not needed due to the color being pretty dark and I liked how it looked after it dried. When it dried I applied helmsman by minwax poly. I let this dry for about 4 days before trying to sand with 220 grit. Being gentile, the first couple strokes of sanding took me through the stain, particularly on the rounded edges, through not exclusively there.
On a second piece the stain came off as I was applying poly on the solid oak edges. I sanded the solid oak pieces down to bare and then re-sanded to 150 grit. I applied one coat of stain being extras sure I got all the excess off. After drying to for 2 days I thought I would try to apply a second coat of stain to see if this would make it less likely to sand through it when trying to sand smooth the poly. As I was applying this second coat of stain, the first coat started rubbing off.

You guys now have all the same information I have. I think that maybe the wood is so dry that it is soaking up the poly rather than building up the protective layer on the surface. Therefore, when he tries to sand it, he is taking off surface wood and thus removing stained wood. The fix is to apply several coats of poly before sanding. However, I have never seen this kind of issue and I am interested in seeing the responses from the community.

-- It may not be pretty...but it's functional.



6 comments so far

View Rich's profile (online now)

Rich

1875 posts in 404 days


#1 posted 01-23-2017 03:36 PM

It’s due to the nature of oil based poly over oil stain. The poly will lift it up. You can use water based poly, or lay down a seal coat of shellac to protect the stain before the oil poly. You can also spray the poly and have less of a problem, but they will still mingle to a certain degree.

-- No matter how much you push the envelope, it'll still be stationery.

View dschlic1's profile

dschlic1

394 posts in 1784 days


#2 posted 01-23-2017 06:49 PM

Probably need to sand between coats with 320 or even 400 grit. 220 is too aggressive. The idea of sanding between coats is two things:
1, Remove any dust or other particles that are sticking up.
2. Provide a SILGHTLY rough surface for the next coat to adhere to.

For my finishes, the sanding of the first coat is usually just for point 1, as the surface does not yet have a sheen.

View pintodeluxe's profile

pintodeluxe

5422 posts in 2628 days


#3 posted 01-23-2017 07:17 PM

This is the very reason I switched to spraying furniture finishes. Since there is no physical contact, there is no lift-off effect.

For a successful wipe-on or brush-on finish, I would sand between coats with a thin sanding sponge in the 800-1000 grit neighborhood. The final coat can be wet sanded with a 1500 grit sanding sponge and water.

These are the ones I use, available from Woodcraft.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View Rich's profile (online now)

Rich

1875 posts in 404 days


#4 posted 01-23-2017 07:29 PM

I really don’t think sanding is going to eliminate the lifting of the stain since it’s still exposed. You need to isolate it with a non-reactive layer like shellac.

-- No matter how much you push the envelope, it'll still be stationery.

View Nathanexplosion's profile

Nathanexplosion

38 posts in 314 days


#5 posted 01-23-2017 10:43 PM

Oak is naturaly sappy wood. Takes about 2 years to dry on its own. Unless kilnd. Dont worry about oak absorbing, it is dense enough. Sounds like your using a protective coat first not last.

-- Nothing is impossible without faith.

View EarlS's profile

EarlS

561 posts in 2162 days


#6 posted 01-24-2017 07:05 PM

I do a lot of staining and use polyurethane (Arm-R-Seal) almost exclusively on my projects.

I typically sand to at least 220 or even 320 BEFORE applying stain. Make sure the stain has 72 hours to fully dry, then very lightly go over it with 400 grit or higher (I use 800 grit) paper to knock down any nubs. You aren’t sanding, you are removing dust or nubs that are on top of the stain. It should be a wipe or two, not scrubbing like when you sand. Wipe off with a clean non-lint rag or non-wax tack cloth. Apply the first coat of poly, let dry for 24 hours, repeat sanding with 800 grit, wipe off, apply second coat, and so on. I usually switch to 1500 grit wet paper after the second coat. Remember the sanding is taking off the finish you just applied so only sand enough to knock off the nubs and dust. There should be very little material removed when sanding between coats. After 3-4 coats, I will apply some Behlens Finishing compound to provide a nice wax finish and hand rub it to a shine.

-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"

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