Chemicals to break down hard foam insulation? - Page 1
Forum section: electronics / repair

author: gnavigator1007
author_rank: Unknown
timestamp: November 02, 2019, 08:21:34 pm
content: Working on repairing an old veterinary scale. One of the load cells I'm not getting anything from. So far I've been carefully chipping away at the insulation that all four cells as well as all wiring is encased in. Seems like this is some variant of the spray stuff. Very tedious and slow going. Any chance someone knows a reasonably safe chemical alternative?

author: babysitter
author_rank: Frequent Contributor
timestamp: November 02, 2019, 08:23:22 pm
content: Start with the least dangerous, acetone, report back when not successful.

author: kizmit99
author_rank: Regular Contributor
timestamp: November 02, 2019, 08:30:04 pm
content: Acetone was going to my suggestion as well... I would surprised if that doesn't work.

author: Kartman
author_rank: Contributor
timestamp: November 03, 2019, 03:39:30 am
content: Sometimes heating the stuff helps. Many epoxies go chalky around 80+C. I use a hot air soldering tool and sometimes the kitchen oven. Obviously you don't want to get things too hot otherwise plastics start melting, so keep it below 100C.

author: amyk
author_rank: Super Contributor
timestamp: November 03, 2019, 03:42:44 am
content: Next step up from acetone would be MEK.

author: beanflying
author_rank: Super Contributor
timestamp: November 03, 2019, 03:51:47 am
content: At a rough guess it will have been a two part Polyurethane foam commonly used for flotation cells in boats among other uses. I have a couple of Heated References that use a similar foam inside the chambers.Based on that keep an eye on MSDS sheets like this onehttp://www.totalboat.com/wp-content/uploads/2018/08/TotalBoat-Polyurethane-Flotation-Foam-2-LB-Density-Activator-Part-B-SDS.pdffor a guide. You are fairly likely to end up with a very gooey mess if you use a solvent to break it down so glove up and drop some plastic on your bench if that could be a problem.

author: gnavigator1007
author_rank: Unknown
timestamp: November 03, 2019, 03:52:18 am
content: No luck with acetone. Even areas i chipped away the surface didn't seem to be affected. Will try heat tomorrow on one of the larger chunks I've managed to excavate. Had been a bit reluctant to use heat, but at this point I'm looking at an awful lot of careful digging.

author: beanflying
author_rank: Super Contributor
timestamp: November 03, 2019, 03:55:23 am
content: Quote from: gnavigator1007 on November 03, 2019, 03:52:18 amThink you have problems this is a giggle I saw a while ago

author: gnavigator1007
author_rank: Unknown
timestamp: November 03, 2019, 03:59:37 am
content: Quote from: beanflying on November 03, 2019, 03:51:47 amThe scale is too big for the bench so I've been stuck working on the floor so far and honestly my back is killing meWill do any testing on smaller pieces first. If I find anything that works, the project will have to move to concrete slab outside. My wife tolerates a lot already and I'm not gonna push it.

author: SeanB
author_rank: Super Contributor
timestamp: November 03, 2019, 11:47:26 am
content: I wanted to unpot a small electrometer module, so dropped it into a jar of pure MEK for 3 months, as that was the time it needed before the epoxy would soak enough to soften up.For your foam the only suggestion I would give is to go to a boat builders supply and get some epoxy remover, which is a witches brew of assorted solvents that will break down the foam, though the electronics and stuff inside will likely be destroyed by it as well. Best is to chip away slowly at it, then use the solvent as a final cleaning method, limiting the time it touches the load cells.

author: jogri
author_rank: Frequent Contributor
timestamp: November 03, 2019, 01:05:00 pm
content: If it is a polyurethane, i suggest you use a concentrated mineral acid (i'd suggest HCl, as it is the easiest to work with). (You could also try either DCM or cyclohaxanone). Just keep in mind that those substances will probably dissolve other stuff too, so you can't just dump it in a solvent bath and come back later. Also, don't forget that dumping chemicals onto a unknown substance can sometimes get you a really nasty reaction. If you don't feel safe handling those substances, don't do it.About the safety of those substances:-DCM: work outdoor, don't get it onto your hands. If you want to use gloves, you'll need either FKM or PE/EVAL gloves. Should be rather effective, but it is classified as hazardous waste (it'll cost you a few bucks to have someone properly dispose it)-Cyclohexanone: work outdoor, don't spill it.-HCl: might produce some unpleasant smells, so you should work outdoor(You could also try HNO3, but that stuff leaves nasty traces when you touch it)You could use a toothpick to punch holes into the foam, that will increase the surface and therefore decrease the time it takes to dissolve the foam.

author: Kleinstein
author_rank: Super Contributor
timestamp: November 03, 2019, 02:52:26 pm
content: Polyurethan foam is often quite sensitive to UV light. A few days in the sun and it turns brown and brittle.

author: jogri
author_rank: Frequent Contributor
timestamp: November 03, 2019, 04:32:27 pm
content: Quote from: Kleinstein on November 03, 2019, 02:52:26 pmI don't think that this will be a efficient as the UV would only affect the outer layer. And if the manufacturer used a pigment to prevent UV induced aging, you are out of luck. It could work if you use a high power UV-B/C lamp (a low pressure mercury one [or any other that emits at roughly 250nm] would be a good choice), but i don't think that normal UV-A from the sun will do the trick.

author: duak
author_rank: Super Contributor
timestamp: November 03, 2019, 11:05:19 pm
content: Lacquer thinner contains toluene or xylene plus a few other things and is more active than acetone.Paint Strippers containing Methylene Chloride might be worth a try. Methylene Chloride is super volatile and softens most polymers and many waterproof gloves.Safest Stripper by 3M (and others) make an alkaline based product that probably won't work.

author: gnavigator1007
author_rank: Unknown
timestamp: November 05, 2019, 12:47:50 am
content: Thanks everyone for the suggestions. Heat was a total failure. Will have to wait until I can get to a marine supply shop (plenty in the area). Found out today that I might have several more of these headed my way. Fun

author: texaspyro
author_rank: Super Contributor
timestamp: November 05, 2019, 05:38:30 am
content: There's very little that chlorine trifluoride won't remove...https://blogs.sciencemag.org/pipeline/archives/2008/02/26/sand_wont_save_you_this_time

author: beanflying
author_rank: Super Contributor
timestamp: November 05, 2019, 05:57:27 am
content: I still like the use of Electric Garden Tillers and hedge trimmers from the video above

author: Jeroen3
author_rank: Super Contributor
timestamp: November 05, 2019, 07:05:10 am
content: Try THF (Tetrahydrofuran), please get a tiny amount and store it somewhere well ventilated and unflammable. (it is perishable and can self-combust)

author: jogri
author_rank: Frequent Contributor
timestamp: November 05, 2019, 08:12:23 am
content: Quote from: Jeroen3 on November 05, 2019, 07:05:10 amThat is a terrible idea, you really shouldn't handle ethers without an extensive background in chemistry: They tend to form highly explosive compounds (peroxides) on the inside of your screw top/plug/whatever you use to seal the bottle, and they will happily explode when you try to open the bottle. This problem gets worse over time, and if you ony use them once in a blue moon (as you do in a home lab) chances are that you forgot this fact the next time you want to use it.Yes, most ethers have BHT added to minimize this risk, but if it gets old enough it can still happen. And compounds that can explode without warning are just not something an amateur should handle.

author: gnavigator1007
author_rank: Unknown
timestamp: November 05, 2019, 11:41:21 am
content: Quote from: beanflying on November 05, 2019, 05:57:27 amThe hedge trimmers weren't the best idea, but the tiller was pretty genius. Enjoyed that video enough to end up watching another. The amount of work put into that ship is really impressive. Would love to see more video of the buildout for the recording studio. Ben does discuss some of the issues in this.https://youtu.be/7xrR0GOkH2g

author: gnavigator1007
author_rank: Unknown
timestamp: November 05, 2019, 11:49:27 am
content: The boat stuff will likely be my last chemical attempt before I go back to careful chipping and scraping. I am wondering now what I'll use to fill it back in. May end up looking into getting some of this boat foam, but not sure if it will set as hard as this stuff did.

author: Jeroen3
author_rank: Super Contributor
timestamp: November 05, 2019, 12:27:19 pm
content: Quote from: jogri on November 05, 2019, 08:12:23 amYes, it is a terrible idea. Worse if you can actually obtain the stuff.

author: Psi
author_rank: Super Contributor
timestamp: November 05, 2019, 12:37:15 pm
content: Quote from: texaspyro on November 05, 2019, 05:38:30 amAh, good old chlorine trifluoride.Makes things any sane person would think of as non-flammable (or even fire retardant) catch on fire explosively.Like bricks, concrete, asbestos, or just dirtI wonder what would happen if chlorine trifluoride encountered azidoazide azide

author: WhichEnt2
author_rank: Regular Contributor
timestamp: November 13, 2019, 09:32:17 am
content: Polyurethane foam can be destructed by DMSOhttps://en.wikipedia.org/wiki/Dimethyl_sulfoxide_(data_page) After applying and some time - foam becomes brittle and easy to remove.There is also a special removers for cured foam, usually in aerosol spay form, e.g.https://penosil.com/gb/cleaners/65-penosil-premium-foam-remover-6023.html

author: pcmad
author_rank: Regular Contributor
timestamp: November 18, 2019, 03:02:04 pm
content: 100% acetone in a venterlated areaand hobby knifes