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Need some help finishing MDF

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Forum topic by Bcemail posted 07-11-2020 03:16 AM 491 views 0 times favorited 14 replies Add to Favorites Watch
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Bcemail

27 posts in 1317 days


07-11-2020 03:16 AM

I built a quick work station for my TS on wheels with an MDF top. I had read somewhere about getting a nice gloss finish with lacquer. Of course, can’t find the video or post or whatever to re-read the details. I decided to give it a shot on the top, and have rolled on a few coats. So far, it still feels pretty rough. I know the lacquer normally doesn’t require sanding, but instructions probably aren’t referring to MDF. First coat or two were soaked up quickly of course. Maybe I need to do more sanding or coats.
Anyone have experience with this? Probably should have primed and used a glossy paint or put some kind of lamination on the top, but a bit too late now. Thanks!


14 replies so far

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ChefHDAN

1705 posts in 3658 days


#1 posted 07-11-2020 08:27 AM

Well it’s a workstation after all anyway, so it’s up to you how crazy you want to get with it. I’ve done a few painted items with MDF, and the first coat, particularly around edges always has to be sanded flat again. I’m betting that you’re seeing some product swell from the product absorption. Think WB stain grain raise which is similar. I’d suggest a 220 light sand and then another coat to see what happens, and then some coats of past wax afterwards.

Good Luck, post some pics.

-- I've decided 1 mistake is really 2 opportunities to learn.. learn how to fix it... and learn how to not repeat it

View Axis39's profile

Axis39

274 posts in 406 days


#2 posted 07-11-2020 01:36 PM

If you’re rolling on lacquer, it’s gonna need some sanding!

Even spraying lacquer requires sanding and buffing to get a deep, wet look.

What kind of lacquer did you use?

-- John F. SoCal transplant, chewer uppper of good wood

View BuckeyeMetz's profile

BuckeyeMetz

13 posts in 1359 days


#3 posted 07-11-2020 02:12 PM

I’m curious what everybody will say about finishing MDF. Did you ever consider using laminate? I’m considering Macgyvering a custom table saw top for my beginner level table saw.

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Bcemail

27 posts in 1317 days


#4 posted 07-11-2020 02:51 PM

Thanks for the tips! I’ll definitely sand and try another coat or two. I’m using Watco gloss lacquer. Probably should have used laminate but had this stuff on hand so gave it a shot. I’ll post some pics after working on it a bit

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SMP

2268 posts in 714 days


#5 posted 07-11-2020 03:04 PM

I usually just roll on whatever is cheap at the big box stores. Polycrylic or minwax poly work well. I just sand between coats.

View CaptainKlutz's profile

CaptainKlutz

3374 posts in 2303 days


#6 posted 07-11-2020 07:39 PM

Hmm. Never tried lacquer on plain MDF?
But
Watco Lacquer is Nitrocellulose based. Each coat is capable of dissolving the surface of previous lacquer coating. Does a rough fibrous surface return after each coat?

Might take 2-3 coats applied back to back before sanding to actually seal the MDF fibers?
Would then spray the final coat(s) as thin as possible to avoid dissolving/disturbing the old layers and raising the MDF fibers again.

More I think about potential struggle redissolving lacquer and MDF fuzz factor: would suggest using something different (glue sizing, shellac, etc) to seal the MDF first, then lacquer as top coat once fibers on bonded down. But too late for that advice. Might have to sand lacquer down to expose the now sealed MDF and top coat with polyurethane instead?

+1 laminate always works, it is just expensive unless you can find remnants from a local countertop shop.

Best Luck.

-- If it wasn't for bad luck, I wouldn't have no luck at all, - Albert King - Born Under a Bad Sign released 1967

View Bcemail's profile

Bcemail

27 posts in 1317 days


#7 posted 07-11-2020 08:35 PM



Hmm. Never tried lacquer on plain MDF?
But
Watco Lacquer is Nitrocellulose based. Each coat is capable of dissolving the surface of previous lacquer coating. Does a rough fibrous surface return after each coat?

Might take 2-3 coats applied back to back before sanding to actually seal the MDF fibers?
Would then spray the final coat(s) as thin as possible to avoid dissolving/disturbing the old layers and raising the MDF fibers again.

More I think about potential struggle redissolving lacquer and MDF fuzz factor: would suggest using something different (glue sizing, shellac, etc) to seal the MDF first, then lacquer as top coat once fibers on bonded down. But too late for that advice. Might have to sand lacquer down to expose the now sealed MDF and top coat with polyurethane instead?

+1 laminate always works, it is just expensive unless you can find remnants from a local countertop shop.

Best Luck.

- CaptainKlutz

Thanks for the help! One area feels pretty good. Not sure if I just put extra on that area? When you say 2-3 coats back to back did you mean without drying? That might build it up a bit more. Guessing I don’t want to use any other product over the lacquer? Might try another couple of coats just to experiment instead of sending everything down.
Used Bondo to fill one little area that was gouged and that’s super smooth!
Thanks

View Redoak49's profile

Redoak49

4812 posts in 2797 days


#8 posted 07-11-2020 08:38 PM

I have tried lots of things on mdf. My go-to now is a coat or two of shellac. Sand it lightly, vacuum lots and use a top coat. Wipe on poly works but easiest is a hard wax and buffed.

View WoodenDreams's profile

WoodenDreams

1099 posts in 720 days


#9 posted 07-12-2020 06:35 AM

All of my workbench table surfaces in the shop are MDF. I haven’t put any protective finishes on them. I figured MDF would be better painted (I not painting them) than risk distorting the surface with oil or water base finish if is soaks in and somewhat blisters up. Mine are screwed on, so if I need to I can just replace them. My assembly/gluing station has a 2”x2’x8’ melamine surface. My staining/finishing station is a old dining room table covered with a plastic table cloth. After using the melamine as a assembly/gluing station, I think my main workbench 4’x4’ will replaced with melamine when the time comes.

View LittleBlackDuck's profile

LittleBlackDuck

5001 posts in 1629 days


#10 posted 07-13-2020 03:06 PM

Depends on the size… For a work station, I’m assuming it’s gonna be large and subject to abuse… making it pretty-pretty is in my opinion a waste of time and resources. Two coats of oil (BLO, tung, danish) will protect it somewhat initially but after a month or two, who gives a crap. You could also wax it to keep it slick to slide timber over… if that’s your druthers.

For smaller pieces (eg. puzzles and boxes) I find a coat of tung oil followed by my 3 wax buffing system (Beall) works wonders on MDF.

-- If your first cut is too short... Take the second cut from the longer end... LBD

View JIMMIEM's profile

JIMMIEM

71 posts in 1650 days


#11 posted 07-13-2020 09:42 PM

Oil based polyurethane works well on MDF. The more (thin) coats the better. I made my router table with an MDF top. Protected the top with oil based poly. Whenever I have a project that needs polyurethane I put a coat on the router table. As an aside, I made my router table fence out of MDF but did not polyurethane it. My workshop is in my basement and the dish washer, which is located above my workshop, leaked onto my router table. The water ruined the unfinished router fence but the table top was fine and the water just beaded up on the poly.

View Rich's profile

Rich

5720 posts in 1398 days


#12 posted 07-13-2020 09:51 PM

I have found that hard wax oils like Osmo Polyx and Briwax Hard Wax Oil are excellent for bench tops, including MDF. They are extremely durable since they were developed for finishing wooden floors, and resist stain quite well. The biggest plus for me is that glue peels off easily.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

View Bcemail's profile

Bcemail

27 posts in 1317 days


#13 posted 07-14-2020 02:31 PM

Thanks for all the help. I’ll try some sanding and another coat plus some wax. Those wax oils look like good products too. Once done I’ll report back!

View Bcemail's profile

Bcemail

27 posts in 1317 days


#14 posted 07-18-2020 07:20 PM

Well, bought another can of lacquer to try some more coats. Sanded with 220 and it felt much smoother. Decided didn’t need any more (think I did 4 first time). Put on some paste wax and it feels great

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