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Poly gumming up sand paper

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Forum topic by KevBotWorkshop posted 10-14-2017 04:00 AM 547 views 0 times favorited 10 replies Add to Favorites Watch
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KevBotWorkshop

9 posts in 217 days


10-14-2017 04:00 AM

Topic tags/keywords: finishing sanding poly polyurethane

Hey all, just looking for insight on people who have worked with Polyurethane before. I have used it in the past when I was a novice and knew nothing about getting a nice smooth finish, but have decided to use it on the project I am working on now.

Working on a computer desk.

I finished the top of the desk with danish oil and then 3-4 coats of poly. The top came out great – zero issues. Final coat I sanded up to 1200 grit. I know not necessary to go that high, but I had the sand paper and went for it and man it is as smooth as a baby’s bottom.

The desk drawer fronts and shelves on the other hand I am having issues. With the top I would sand in between coats with 220 I believe and I would get fine dust. Now I am getting gummed up sand paper. I have a couple thoughts as to why, but wondering if someone had different thoughts.

I got a little anxious and thought I would be able to do all the finishing in one day. I put on danish oil waited a couple of hours and then started applying coats of poly. My thoughts is that I should have let the danish cure for a day (recommended on the container) and gone with light coats of poly and let the first couple cure for longer times.

At this point I am still getting gumming so I am just leaving it for then next 36ish hours as I cant work on it anyways. I hope I get that dust back and can finish these bad boys up.

I really hope I dont have to sand back down to the wood and do finish over again. < Does anyone think I have to do that?

Any insight would be great. Thanks all!

-- Kevin Johnson, Instagram - @KevBotWorkshop


10 replies so far

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jonah

1471 posts in 3137 days


#1 posted 10-14-2017 04:07 AM

You definitely didn’t let the oil cure properly before adding the top coat. It’s never really going to cure, unfortunately.

You’ll have to sand down to bare wood and start over. Honestly, I’d wait even longer than a day to let the oil cure fully. I haven’t used danish oil in years, so I can’t remember how quickly it actually cures, but most oils take forever.

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MrUnix

6010 posts in 2037 days


#2 posted 10-14-2017 04:17 AM

It will dry… but it’s gonna take a while. I have done Danish oil followed by poly on many projects, and always wait as long as I can for the Danish oil to cure before applying the poly… sometimes up to a week or longer. Never had a problem as long as I waited long enough between the two.

Let your drawers sit for a few days. They will eventually dry.

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

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jonah

1471 posts in 3137 days


#3 posted 10-14-2017 04:41 AM

He already put the poly on though. With poly on there, the oil will never dry.

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MrUnix

6010 posts in 2037 days


#4 posted 10-14-2017 04:52 AM

He already put the poly on though. With poly on there, the oil will never dry.
- jonah

It will given enough time… the oil is keeping the poly (which is oil based as well) from fully curing, so it’s still leaching oil through it. Eventually, it will cure – but will take a while. Elevating the temperature and providing proper ventilation will help speed the process.

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

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coxhaus

64 posts in 733 days


#5 posted 10-14-2017 06:01 AM

Try some chemical stripper you can buy from Walmart then let it dry and sand. Much easier with less sanding.

Buy disposable gloves to use with the chemical stripper. They sell them right there by the stripper in Walmart. Paint the stripper on with a disposal brush. I like to use a plastic putty knife to remove the stripper off the wood after you let it set for a few minutes. Let the stripper set for how ever long is recommended on the can.

View Rick_M's profile

Rick_M

10638 posts in 2218 days


#6 posted 10-14-2017 06:03 AM

Common mistake, lots of us have done it. Pick one finish and stick with it until you understand it. Don’t mix finishes except on rare occasions, and don’t worry about those rare occasions for now. I also suggest a good book on finishing, I like Understanding Wood Finishing by Flexner; read that and you’ll be ahead. It’s been around for years now and is solid advice for hobbyists. If you need to remove finish, a scraper will be quicker and easier than sanding.

For most things I use shellac because it’s tough enough that it was used on floors for a long time, it dries very fast, you can recoat at any time, and it’s very easy to repair. But for tabletops or anything that needs strong protection, I am now using a waterbase polyurethane. I used to hate them but the newer ones dry fast and are low odor. If you are building furniture for your house and want everything to match, then I would go with waterbase poly. I wouldn’t bother with oil, imo it’s more hassle than it’s worth and anything linseed based will yellow the wood, but if you do want to deal with oil then I would top it with shellac.

-- http://thewoodknack.blogspot.com/

View Andybb's profile

Andybb

552 posts in 442 days


#7 posted 10-14-2017 07:58 AM

What is the purpose of putting the Danish oil under the poly?? Color? Why not just skip the Danish oil? If you’re looking for color and fast drying why not a water based dye under the poly or water based Varathane instead of the poly.?

Or, give it a week or two until it hardens up.

+1 on Flexner’s books.

-- Andybb - GO HAWKS!

View HorizontalMike's profile

HorizontalMike

7661 posts in 2752 days


#8 posted 10-14-2017 10:23 AM

400 and 600 grit wet/dry sandpaper works, as long as you are sanding wet. And “wet” can mean a light oil, or even JPW, not just H2O.

-- HorizontalMike -- "Woodpeckers understand..."

View bondogaposis's profile

bondogaposis

4480 posts in 2190 days


#9 posted 10-14-2017 02:36 PM

I got a little anxious and thought I would be able to do all the finishing in one day.

That is your mistake right there. Not possible with oil based finishes.

All of my problems with gummy finishes have come from using Danish oil. You have got to let that stuff cure before applying another coat. I’m allowing 48 hours now to be safe with it.

-- Bondo Gaposis

View CharlesNeil's profile

CharlesNeil

2144 posts in 3709 days


#10 posted 10-14-2017 05:07 PM

Try wiping it down good with naphtha , for whatever reason, it sure seems to help “gummy” stuff dry faster ..
AKA.. charcoal lighter .

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