Removing mastic while preserving hardwood floors underneath?

Submitted by SummitWanderer t3_z71y4o in DIY

Hello all,

Long time lurker, first time poster. Inherited my grandma's house in the last year and starting to renovate. Built circa 1930 in the high desert southwest, so it's a fun one. I started ripping up carpet in the hall last night and found that under two layers of carpet and two layers of linoleum there's what appears to be a hardwood floor in decent to good condition underneath. Problem is that on the last layer is a teal-ish linoleum that may contain asbestos and black mastic that may as well.

I've done some googling on how to remove mastic, but most of what I've seen so far is specifically meant for concrete, and what little else I've found will still most likely strip the varnish from the wood and/or cause some of the tar-like mastic to seep further down into the wood. So far the best plan of attack I have is to get some Bona hardwood cleaner and spray that on the floor and wipe/scrape it up with a blade while keeping it wet. I reached out to my coworker who is certified to test for asbestos and he thought that would be fine, I'd be in full PPE.

My question is, has anyone had any success in removing mastic like this from a hardwood floor, preferably without stripping the top coat from the wood? Is there a solvent that would do so, or am I best off just putting in the elbow grease with the Bona (which I'm okay with doing if I have to)?

Here is a photo of the mastic if it helps:

Picture

Thanks!

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Comments

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Nonanonymousnow t1_iy4hml7 wrote

Wallpaper steamer works great for this. Get it wet/warm enough that it comes up with a drywall knife. It'll stay gummy that way so you're not masticating it into dust.

Of course, remove at your own risk as it may contain asbestos.

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icosahedronics t1_iy55exu wrote

i used a wallpaper steamer for this (along with all the PPE). it worked fine, a bit of water was absorbed by floor boards but no damage after letting it dry out.

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SummitWanderer OP t1_iy563fj wrote

Ok, thank you. I have a wallpaper steamer at home so I'll try that!

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SummitWanderer OP t1_iy4jzfl wrote

I had seen a guy doing that on his concrete floors, but I was under the impression steam is very bad for hardwood floors?

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plaidbanana_77 t1_iy51gix wrote

The tar is also not good for hardwood floors. Steam is at least less bad than tar.

At this point you cannot fuck it worse than it’s already fucked. Outcome options are horrible failure which results in some nice looking LVP, or shining success resulting in perfectly refinished hardwood. Both outcomes are wildly better than where you are now with carpet ripped up and linoleum partially removed down to the uneven adhesive.

Most adhesives will come up with heat or a solvent. Try steam and heat gun before solvent(diesel, mineral sprits, turpentine) but keep a fire extinguisher and water bucket nearby when using the heat gun. Use a 4” metal putty knife, so you don’t melt it to the floor, to scrape away tar loosened by the steam/heat gun.

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WhyKnott2Day t1_iy6uhyr wrote

Agree except NO heat gun... use steam and a putty knife. A heat gun used on mastic and/or unknown "varnish" can (and will) cause toxic fumes...

Source: I have refinished a third of the wood floors in my 122 yr old house, most of which have/had at least 3 layers of linoleum and 1 or 2 layers of carpet and foam padding... ended up hospitalized for acute respiratory distress due to chemical pneumonia from using a heat gun to soften the mastic... Took 5 months to recover fully.

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SummitWanderer OP t1_iy5dlm6 wrote

Thank you for the input! Looks like I'll be pulling out my heat gun!

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dynobadger t1_iy52nts wrote

It's not great, but the varnish should resist water to some extent. And the flooring will dry out after the steaming. If you go this route, be careful scraping wet wood. It becomes very easy to start tearing fibers out of the wood.

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SummitWanderer OP t1_iy55vtp wrote

Thanks! I appreciate your input!

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n0tjamesfranc0 t1_iy6cr2j wrote

Hardwood floor guy here. If you do this with the steamer and it works let the floor moisture content lower back before refinishing it. I'd recommend about 2 weeks to let it dry and reacclimate to the house's humidity.

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n0tjamesfranc0 t1_iy6ddq9 wrote

If you get the heavy chunks of mastic on some floor refinished might be willing to just use a belt sander with a really aggressive grit for the remaining bits. It gunks up the drum and wheels on the sander so many will refuse to do that. I've done it a few times and it worked well, just needed to clean the machinery throughly afterwards.

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WhyKnott2Day t1_iy7b6z5 wrote

No offense, but it is never a good idea to dry sand anything that has even the slightest possibly of containing asbestos, that's how it becomes airborne and gets into your lungs. Always keep anything you suspect that may potentially contain asbestos wet so it doesn't become airborne...hence using a wallpaper steamer and a putty knife to remove the mastic...and then do a light damp sand, wiping down as you go, to make sure you have removed every bit of it before letting it completely dry (a good 2 weeks, or more if it's humid) and then begin your refinishing sanding.

Source: https://inspectapedia.com/hazmat/Asbestos_Wetting_Procedure.php

Edit: added source

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BikesMapsBeards t1_iy8b1uj wrote

I’ve done this and it is definitely the easiest way to go. No strippers or chemicals to neutralize. Just be sure to let it dry really well before sanding.

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JustAnAverageGuy t1_iy4ga7a wrote

Firstly, be aware there is a high chance it contains asbestos. Get it tested, and ensure you follow guidelines and regulations for its removal and disposal. Don’t just rely on your neighbor.

I’ve used these before with success on wood, you just need to be careful on controlling the aggressiveness. https://www.jendcosafety.com/diamabrush-7-mastic-removal-hand-tool/

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SummitWanderer OP t1_iy4kiok wrote

Thanks for the reply, have a sample to test when ready. I'm not sure I have the steady hand to keep it from biting the wood unfortunately :(

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idonotselltoepics t1_iy4rdxs wrote

I'm no expert but have dabbled in old hardwood floor restoration before, in the best of worlds after you removed all this stuff it would be good to give the entire floor a good sanding and re-varnish. These steps would eliminate any minor damage caused by biting the wood.

But then again some of your other comments give me the impression you intend to preserve the varnish so maybe none of this applies to your situation

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SummitWanderer OP t1_iy4wdwq wrote

The plan is to eventually sand everything and re-varnish it, but 90% of the house is hardwood in seemingly good shape. I was honestly hoping for some miracle cure that might let me just wipe the old mastic off 😂 It's still slightly tacky so there was a hope

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JustAnAverageGuy t1_iy5iy9c wrote

yeah... you're going to have to plan on refinishing the floors at the same time.

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PlavaZmaj t1_iy53nyq wrote

Asbestos is the bestos. Can confirm, should be tested. Good luck.

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Scooter_127 t1_iy4q2pj wrote

I wouldn't worry too much about the finish on the wood flooring - you're going to have to strip it and refinish it anyhow.

Also, don't get too awful excited about the asbestos. It's not the 'plutonium' so many people think it is and a couple accidental instances of inhaling some won't give you lung cancer, and sounds like you have the PPE covered. Chew on this: A lot of aftermarket brake pads still have asbestos.

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SummitWanderer OP t1_iy4sg5n wrote

I know it's a vain hope. The plan is to fully sand and refinish the whole house at some point, but if I can get away with not having to for the next year while I'm remodeling it would be a bonus. But the flooring above needs to go now unfortunately.

I only mentioned the asbestos in the first place because I knew people would warn about it. If it were friable I would be much more concerned, but the tile appears to be taking most of the mastic with it and my understanding is that the tile is the greater of the two evils. I've been around abatement teams and seen how they operate, and truthfully if I'm gonna die of lung cancer it'll most likely be from the air quality in wildfire season ¯_(ツ)_/¯

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sti-wrx t1_iy53xcj wrote

Mesothelioma is a different beast from smoke inhalation - I’m only saying this because I work around Asbestos frequently and don’t take any chances.

Scar tissue in your lungs is a different issue than potential cancer you would get from smoke exposure - whatever you do make sure you mask up.

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btribble t1_iy5em25 wrote

Mask up with a good mask, get a couple cheap disposable protective "onesies" online, put plastic sheeting on everything you don't want dust on/in, and create negative pressure with a box fan in an open window. Keep dust down with a spray bottle with water in it. Wear your worst clothing and toss it in the trash. Shower when you're done. It's not hard or expensive to be safe.

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SummitWanderer OP t1_iy5hcfr wrote

Thanks! Have the Tyvek suits already and a p100 respirator. Also already have 6mil plastic sheeting on site due to a separate clean up issue ( mice 😞 )

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btribble t1_iy5jwwv wrote

Don’t forget to toss your respirator filters after you complete the work.

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theRegVelJohnson t1_iy51k10 wrote

With large floor buffer and a mastic removal wheel.

https://youtu.be/8z-U2pmJi4s

If you're question is "Can I remove this stuff and get to 'nice' floors with no additional steps?", then the answer is most likely "No". Once you get that stuff up, the floors are going to need to be refinished.

Are you going to have someone else refinish them? If so, I'd just have them handle it. If you're going to refinish them yourself, you'll end up having to rent a machine to do it anyway. Call around to local tool rental places. Your local big box might have them, but the independent/dedicated rental outfits are often more helpful if you tell them what you're trying to do and they can get you the right stuff.

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SummitWanderer OP t1_iy5eggo wrote

Thanks! I have access to a buffer already. I refinished our deck a year or two ago with a floor sander I rented, but for this project that's for after I get this mastic up. I'll probably be finishing the floors myself this time as well.

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FRIKI-DIKI-TIKI t1_iy4vpxl wrote

I had the same thing done at my house they put a liner down with tar mastic and then tiled over the wood floor. I tried everything and then remembered some words of wisdom my grandfather gave me about getting tar off of vehicles and that was diesel fuel liquifies tar. So after trying everything, I came up with a plan to get a mop and bucket, diesel fuel, play sand and a wire brush on a broom handle. I would mop the diesel fuel onto the floor, let it sit for a little while, hit it with the brush and it would come right off with no effort, but it would mix with the diesel fuel and make a black thick liquid. So I would throw the play sand on it to soak up the liquid. Then use a broom to move the sand around until it was too soaked to pick up anymore, then I would sweep it onto a shovel and dispose of that sand.

Every other way was an inch by inch method, you cannot sand it off, scraping it off does not work, and strippers do not lift it off very well. Using diesel to liquify it, was a smelly and messy process, but I did about 1400 sq ft. in a day this way, where as all the other methods I tried combined only netted me about 100 sq. ft over the course of several days.

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bryan_pieces t1_iy6s1gn wrote

Dude you mopped your house with diesel fuel? Using it outside to remove tar from a vehicle is an entirely different circumstance. Holy shit.

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FRIKI-DIKI-TIKI t1_iy9d7v4 wrote

Yep it worked great, it got sanded and refinished, so it was a momentary pain in the ass to restore some Dade county pine floors. It is not like I mopped it with gasoline, Diesel is not explosive or highly combustible.

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silver_chief2 t1_iyat3jq wrote

>WOW. Thanks. So you put on the diesel on the mastic. The how to you remove the goo?
>
>Years ago I removed black tile adhesive gunk from concrete using solvent. I was going to go to a bar after ward. I drove onto the interstate off ramp. I was higher than a kite. The cop let me off with a warning. I went home instead.

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FRIKI-DIKI-TIKI t1_iyc0tiu wrote

With a wire brush, and then sand, you use the sand to soak up the tar/diesel goo. It is a pretty easy process.

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SummitWanderer OP t1_iy5fgke wrote

The good news here is that I've only got less than 250 sq. feet to do, so if I have to work in small sections it's not a deal breaker. I am wary of using diesel though, maybe I could try a small patch.

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FRIKI-DIKI-TIKI t1_iy5ph2x wrote

I have not tried it, but you could try baby oil or peanut oil. I don't know if it is because tar and diesel are both petroleum products that it dissolves it or if it is because diesel is a thin oil.

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robosmrf t1_iy52eqh wrote

I prefer a heat gun on stuff like this.

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andrew65samuel t1_iy58cks wrote

Heat gun and a draw scraper worked for me. Make sure you get a file and keep the scraper blade very sharp.

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Wilynesslessness t1_iy4q5nk wrote

4" razor scraper and elbow grease, but the blade will want to dig in. There are handy carbide scraping tools that may resist gouging the floor as well.

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SummitWanderer OP t1_iy5fl7z wrote

Thanks! Have you found any one brand to have a better product?

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Wilynesslessness t1_iy5gsa0 wrote

I haven't used many different brands, but the bahco ergonomic ones are great.

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Nugg3rz95 t1_iy4sxzj wrote

Southwest high desert? High desert as in Victorville in southern cali?

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FindTheRemnant t1_iy4xzya wrote

Try boiling water. It'll probably turn into a gummy mess that you can scrape of really easy. The wood will be fine if you dry it quickly after. Do a little area at a time. It doesn't need to soak in.

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NinjaMars t1_iy51svg wrote

Probably not practical with how much you have to take off but I was able to wipe off a small area with Goo Gone

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ERTBen t1_iy55j88 wrote

Pay someone to do this. They’ll have the right tools and techniques, and will be able to refinish after. You can’t get it off without needing to refinish the floor.

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RandomAverages t1_iy604v7 wrote

If you can get the bulk up like in the photo and have the 4” scraper as mentioned before, try and turn the blade over to the flat / dull side to get that residual stuff. Sometimes it works better than the sharp side that digs in.

Good news: even if it is asbestos, it’s most likely non-friable, and there is a less likely chance that it’ll become airborne versus cutting with a circular saw, or dry sanding.

https://www.fs.usda.gov/eng/toolbox/haz/haz07b.htm#:~:text=Category%20I%20non%2Dfriable%20ACMs,locked%20securely%20into%20the%20material.

We have used our regular mastic remover after the bulk is up and it will soften. And make it easier to remove, but not sure how much damage the chemical will cause in between the slats.

Good luck.

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SeaofSounds t1_iy61ez6 wrote

They make a citric based mastic remover, green scrub pads, spot remove it and absorb as you go, then you could ideally sand the floors....

Edit....any mechanical removal will have disastrous results....

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kikilucy26 t1_iy6exha wrote

I used a heat gun and a drywall knife. Took forever and gave up half way. Can you please let me know the result of the asbestos test? I had black mastic just like that on the original wood floor.

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davidmlewisjr t1_iy77ok5 wrote

Most linoleum contains Jute. Why do you suspect asbestos? Are you planning to sand, or scrape?

Try some WD-40 on a spot, let it set, then see if it wipes away. Varsol was a thing , once, and still is effective. Try some of that for comparison.

Ventilation is your friend.

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SummitWanderer OP t1_iy88g3b wrote

The age and color. I routinely work in old buildings in my area that potentially have asbestos, and so I've tried to learn what types of materials may have it. I ran across something similar to this before in my area that was tested and positive, but it wasn't my problem to deal with then.

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davidmlewisjr t1_iy8a89i wrote

Most linoleum I have come across is ancient, not glued down. Tacks around the perimeter. Good luck with your project.

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phiinkes t1_iy7pes8 wrote

Buy a dust mask with a great seal and replaceable filters and rent a floor sander from True Value (or whatever equipment rental place is in your area,) and prepare for a lot of sanding, vacuuming and sanding again. I have done it and it is a pain, but it really clears the floor up nicely. Keep in mind, you’ll have to match stain and finish again.

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SummitWanderer OP t1_iy885ke wrote

Will do once I get the glue up! Not going to risk it with the mastic on there though :/

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famous_shaymus t1_iy7vxi4 wrote

As someone who has refurbished old hardwood floor (that were hidden under carpet), I can tell you that getting that gunk off the floor will probably be one of the lesser time-intensive parts of the project. Refinishing floors is a huge project. I am a DIY-er to a fault, but we were quoted ~3k for someone to do it for us; that is, sanding and finishing. I would totally do it over though — the hardwood was totally worth it! It may be worth it for you to buy, rent, or borrow a floor orbital buffer. Luckily I had a friend who had an Oreck orbital buffer that he uses to clean the tile in his restaurant. He let me borrow it and after a trip to the Oreck store, I was able to find everything I needed for the entire job. Maybe you have a connection like that?

Best of luck!

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SummitWanderer OP t1_iy881ce wrote

I can sympathize with that lol, grew up in a very DIY family and that's just how I was raised. Plus we live in a rural area so contractors are expensive and have very little competition.

I've rented a floor sander from Home Depot before, but I'm not sure if it was a true orbital sander or not - wasn't a belt sander though - and it worked very well. I have a few connections, plumbing and electrical. And now that you mention it, maybe even a floor sander. I had forgotten I have a coworker who I think has one he might lend. Thanks!

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Mayor_of_Pea_Ridge t1_iy8fbkj wrote

You're getting lots of conflicting advice, so I'll go ahead and throw in some more. Replace the floors if they're made out of something common like skinny oak boards that you can still buy today. It's soooo much easier than farking around with solvents and scrapers and steam and whatnot. Probably less expensive, too. It doesn't take much time to tear out a floor by making a few slices with a circular saw and prying sections of flooring/tile/whatever up with a crowbar. If you want the new floor to look 100 years old, have at it with a hammer and a drill and you can make dents, holes, and gouges just like your restored original floor would have.

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MisterIntentionality t1_iy8g3vi wrote

If there is asbestos in all that, I would hire a remediation company to remove, and yeah you are going to lose the wood floors.

The only way I can think to keep them is by planing them down to remove the outside.

You are talking extreme labor and time as well as obscene risk to your health.

There is no way you will be able to do this properly with the floor laid in place. You'd have to pull up each plank and plane. You'd have to anyways and refinish the floors for them to not look like complete shit.

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Taynt42 t1_iyef2fw wrote

There’s no way to do it and “save” the varnish. The varnish is already ruined, just sand/grind the whole thing down and refinish it. I would also want to save steps in your shoes, but unfortunately it’s too late. Best of luck!

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velifer t1_iy57kov wrote

That wood is almost certainly subfloor, not floor.

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