How to strip stubborn old paint?

[n8n]

Any ideas? What would you use?

I'm at my girlfriend's place and she decided to clean the years of dust wildlife out of the ductwork. Unfortunately two of three return grilles have layers and layers of paint on them and they're being very stubborn; repeated applications of methylene chloride are not really getting it done. I tried to rig up an electrolytic tank to cook off the last of the paint but it's not working; the last time I refinished something at her place I used an old UPS battery to jump-start a battery charger to provide a 12VDC power supply but that's not getting it. Manually removing the paint from each louver would be painfully slow. I feel like I got volunteered for this job without the other parties involved realizing how much work it'd be and now I'm stuck.

She doesn't have a good drill or wire brushes, all I've got to work with is some Scotchbrite pads left over from the last metal finishing project and some HF wire toothbrushes both of which are clogging to uselessness almost immediately.

Ideas...?

New grilles I'd prefer not to do as these are nice heavy ones from the 60s that are about twice the metal thickness of anything you can buy today, but I'm starting to get a little angry at the morons over the years who were too lazy to remove them when painting the walls...

Just wanting to see if I was missing a good trick before I start buying more stuff...

 

[txvwnut]

Get an old crock pot and add water and put it on high and drop in the grilles and let them cook. It should soften the paint enough that it will scrape off with relative ease.

 

[tcianci]

Any number of commercially available paint strippers will work, they just require patience. If you're not the patient type, find a local sand blaster, this type of stuff is what they do. It may even be less expensive than your next jug of stripper.

 

[Platonic Solid]

I assume this is standard brushed on acrylic latex. Thus: Peelaway 6. The only product that will take all the layers off in one application.

 

[n8n]

The problem with this particular paint is that it just turns into a gummy sticky goo when hit with the stripper, it doesn't bubble up and peel off like I'm used to where you then just hit it with high pressure water and it's gone.

The crock pot idea is good but not for this app. The grilles are returns and barely fit in the large storage tote I've been using to cook stuff for derusting.

I may have to just run out and buy a cheap 12V battery to make this work... either that or stretch screen across the openings (to prevent canine intrusion) and work on it another day.

As an aside, does anyone besides me find it odd that the big box stores sell paint stripper but no gloves that are actually rated for use with methylene chloride?

 

[slip knot]

I keep an old crock pot loaded with a gallon of stripeez stripper. turn it on let it cook over night and the part is clean to bare metal. I do a lot of rental rehabs and thats the easiest way to clean knobs and hinges of paint junk. I dont buy new stuff because most replacements are ****.

 

[n8n]

I dont buy new stuff because most replacements are ****.

That is the truth, in many areas. Sometimes I enjoy refinishing/refurbishing old stuff, sometimes it's a chore, but it most if not all cases it seems to be a necessity to avoid downgrading. I could go on a whole rant about the race to the bottom in terms of quality but I'm sure it's just preaching to the choir for many here.

 

[Stuart in MN]

The problem with this particular paint is that it just turns into a gummy sticky goo when hit with the stripper, it doesn't bubble up and peel off like I'm used to where you then just hit it with high pressure water and it's gone.

The crock pot idea is good but not for this app. The grilles are returns and barely fit in the large storage tote I've been using to cook stuff for derusting.

Try scraping it off with a putty knife instead of using a pressure washer. Also, make sure you don't brush it around too much when applying, the more you mess with it the less effective it is - just slop it on and leave it. Also, make sure you're waiting long enough, give it time to work.

Cooking in hot/boiling water should work as well, just get a big enough container (like a wash tub) and put it over a fire or a barbeque outdoors.

 

[Platonic Solid]

The problem with this particular paint is that it just turns into a gummy sticky goo when hit with the stripper, it doesn't bubble up and peel off like I'm used to where you then just hit it with high pressure water and it's gone.

Peelaway 6 is not like any other paint stripper. You goo it on - wrap in the special paper to keep it moist for 24 hrs - all the paint will be goo the next day.

 

[Platonic Solid]

Though you don't need the more expensive Peelaway 7, I used it to remove undercoating from my 73 Mustang wheel wells (link).

 

[countryroad82]

Blast cabinet.

 

[nehog]

Use care: years of paint means high potential of lead. Using anything abrasive (wire brush, for example) that makes dust may create hazardous conditions. What others say about 'cooking' with chemicals (with care) sounds like what I'd try.

 

[ford33]

Consider replacing the grills with new. What's so special about these grills other than they are made of thicker metal? Seems like lots of work for something that is nearly invisible in any home. I get it that you want to keep the character and re-use it but your time is valuable.

 

[kbs2244]

I would go back to the methylene chloride.
Get a shallow pan, just deep enough to submerge the grate, put a metal cover over it to prevent evaporation, and let it sit a week.
You just have to give it time to work.

As some Brit said….
“Time is on my side….”

 

[Dennis Leigh Henry]

"in the day" a small propane torch and a putty knife would make quick work of this. Today.. I'd sandblast them....

 

[NUTTSGT]

Consider replacing the grills with new. What's so special about these grills other than they are made of thicker metal? Seems like lots of work for something that is nearly invisible in any home. I get it that you want to keep the character and re-use it but your time is valuable.

It might be due to the fact that some of the older grilles are larger than the stuff available today or they have to be special ordered.

 

[over40pirate]

If you have something you can submerge the grills in, you can mix TSP with water, and heat to below the boiling point. All the paint will fall off.
Sorry, not sure of TSP to water ratio. I read about this over 40 years ago, in a Popular Mechanics mag.
After trying it I mentioned it to a friend who does restoration to Victorian houses. After trying it, he had a welder, weld him a shallow tank, with long propane burners below, to allow him to put in large louvered shutters.
Saved him a LOT of time.
Just don't leave any wood in too long.

 

[tcianci]

Your mention of the TSP reminded me that When I was building my 40, I used a pail full of hot water and Drano to cook the paint and crud off my headlight buckets. It worked great. 2 Weeks later Bob Drake introduced his hydro-formed headlight buckets at a fraction of the cost of his previous offerings. Timing is everything!

 

[n8n]

Hmm... finding a container big enough might be a problem but I wonder if oven cleaner will get it done? I've used that for nasty car parts with success before. Have to try it next weekend though, this is going to be a hell week I can tell.

 

[tcianci]

Yeah, oven cleaner will probably work, especially if your grilles were painted with hamburger grease.

 

[dogdog]

paint stripper. rubber gloves / mask / googles.. and a scraper / cheap throw away hand wirebrush from HF is about the only thing that would work... if you still want to electrolysis .... think you will have to expose enough metal to get the electrons flowing.... then it will cascade, might take a while if you don't have a good 24v supply..... my radiators ( 8+ ) heavy ones, took about a week in the electrolysis tank to work on the 30+ yr old aluminum paint, took about 2 days and 2 gallon of paint strippers each and some skin burn from acid on the ones I used paint stripper. No amount of wire brush would help.


besides, it's your girlfriend's place right? Infest her place with your tools. lolz

 

[toplessHO]

Ive made soak tanks by digging a hole in the sand the same shape as the part.
line the hole with heavy plastic(old water bed worked great)
cover the tank to prevent evaporation.
Test to make sure the stripper or derust product wont attack your liner.
if you dont have a place you can put this in build a frame with 2x4s and plywood and do
the same

 

[HMCFab9]

Maybe try a different stripper. Zip strip?
I normally use "Aircraft remover" & it works excellent, but is made more for automotive finishes.
When you apply the stripper, cover / wrap the piece with disposable plastic. That keeps the stripper from evaporating & gives it more time to soak into the part.
Also, when applying, apply it & leave it. Don't go over it multiple times as that breaks the "seal" created when it is first applied.
I'd recommend sandblasting, but I worked in an automobile restoration shop & a guy brought a similar item in to be stripped.... (his wife seemed to like to paint Every year) There was so much paint on that vent that the holes were almost completely filled in with paint. We also tried stripper (no go) then tried blasting (also no go) because the paint was so thick that the sand just bounced off like it was rubber.
We ended up soaking it in a pan full of stripper because nothing else would work. (still took a while)

 

[Lippyp]

Over here there are commercial companies that specialise in stripping paint, I had all the original doors dipped from our last house along with four cast iron fireplaces and they came back clean as a whistle. they can use much more aggressive chemicals than you can at home and also keep them hot. Might be worth hitting google.