Answers.Body: <p>Take it for what it is, I am not a material scientist and this is not a guarantee that the following information will work in your case.</p>
  <hr />
  <p>I believe your approach is correct, or at least as good as you'll be able to get considering the material properties of the bricks and the glue.</p>
  <p>LEGO bricks are <a href="https://en.wikipedia.org/wiki/Lego" rel="nofollow noreferrer">made of ABS plastic</a> (at least after 1963).</p>
  <p>According to data from the Cole-Parmer <a href="https://www.coleparmer.com/Chemical-Resistance" rel="nofollow noreferrer">Chemical Compatibility Database</a>, ABS plastic is very susceptible to damage from nearly all the normal solvents used to remove PVA glue.</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th>Chemical</th>
  <th>Compatibility with ABS plastic</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td><a href="https://www.coleparmer.com/Search?searchterm=Acetone" rel="nofollow noreferrer">Acetone</a></td>
  <td>D - Severe Effect: Not recommended for any use.</td>
  </tr>
  <tr>
  <td><a href="https://www.coleparmer.com/Search?searchterm=Methanol%20(Methyl%20Alcohol)" rel="nofollow noreferrer">Methanol (Methyl Alcohol)</a></td>
  <td>D - Severe Effect: Not recommended for any use.</td>
  </tr>
  <tr>
  <td><a href="https://www.coleparmer.com/Search?searchterm=Vinegar" rel="nofollow noreferrer">Vinegar</a></td>
  <td>A - Excellent</td>
  </tr>
  </tbody>
  </table>
  </div>
  <p>Vinegar looks like it may work, especially if you expose the glue to soften it before attempting to remove it from the bricks. Unfortunately, the instructions are almost certainly beyond saving.</p>
  <p>Concerning heat, ABS <a href="https://en.wikipedia.org/wiki/Acrylonitrile_butadiene_styrene" rel="nofollow noreferrer">appears to be safe</a> until around 80°C (176°F) when it starts to deform. This is good considering <a href="https://www.sciencedirect.com/topics/chemical-engineering/polyvinyl-acetate" rel="nofollow noreferrer">PVA softens as early as 30°C (86°F)</a>. However, as Alex points out, <a href="https://bricks.stackexchange.com/a/100/17802">LEGO recommends using water no warmer than 40°C (104°F)</a>.</p>
  <p>You might try submerging the LEGO-berg in hot water for an extended period of time (articles I found suggested multiple hours, changing the water as needed) then using a syringe or spray bottle to apply vinegar to one area at a time. With some force, the weakened glue should release. Assuming it has weakened sufficiently, wiping with a course cloth should remove the residue.</p>
  <p>It is unclear in my searching whether time is a significant factor in the susceptibility of PVA glue to heat. It is a resin, so there may be some long-term curing that prevents the glue from re-softening, but I couldn't find a definitive source one way or the other.</p>
  <p>As an additional consideration, exposure to extended heat, chemical treatments, and physical cleaning may impact the surface quality of your bricks. Additionally, if the solvents present in the glue when it was applied to the surface also affect ABS, the glue may be bonded to the structure of the brick, not just the surface. If this is the case, you will not be able to salvage the brick without a destructive process like sanding that will inevitably leave signs.</p>
  <p>If you can identify a small chunk of bricks to test the process on, you can at least see if heat and vinegar are a potential solution for the rest of your bricks.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-06-02T06:01:57.030Z
Answers.Text: 80°C? Well, LEGO recommends using temperature no more than 40°C when washing bricks. I wouldn't use liquids much warmer than that. And in case there are any CA bricks they will deform under any warmer temperature (if they haven't deformed yet).
Answers.UserDisplayName: Alex
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-06-02T09:17:03.817Z
Answers.Text: Up to 40 Celsius is fine. I have washed Lego in the washing machine on the 40 degree program before. (Take a pillowcase. Load with Lego. Tie it very securely shut and wash on the 40 degree fine cloth program without using the centrifuge.)
Answers.UserDisplayName: Tonny
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-06-02T09:23:37.930Z
Answers.Text: I'm having a small fist-size clump with about 20 bricks in it currently sittng in hot water (tap-water, as hot as I can stand to stick my hand in. Should be around 40 degrees). Will replace the water every 30 minutes or so. Been doing this for 2 hours now. So far the glue doesn't appear to be softening at all. I'll let it work in for a day or 2. After that I will try vinegar.
Answers.UserDisplayName: Tonny
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-06-02T10:24:37.947Z
Answers.Text: @Tonny please update us on how it went!
Answers.UserDisplayName: htmlcoderexe
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-06-02T10:29:57.613Z
Answers.Text: @htmlcoderexe I will write a self-answer with a progress report. Will probably be in the weekend as I have to make a business trip tomorrow and Friday.
Answers.UserDisplayName: Tonny
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-06-02T10:34:28.673Z
Answers.Text: Sweet, good luck with the bricks and with the trip!
Answers.UserDisplayName: htmlcoderexe
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-06-02T11:54:43.453Z
Answers.Text: @Tonny one other thing you could consider with large clumps like this, is to see if it's possible to increase the surface area that's exposed to heat/liquid. If you have a bit of knife skills and the clumps allow it, you could try using a sharp blade to cut the large clumps into several smaller ones (increasing the surface area), or even shave off as much of the glue as possible before applying any water/vinegar, which can save a few rounds of soaking because you're now directly heating/soaking the inner layers of glue.
Answers.UserDisplayName: Tinkeringbell
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-06-02T11:59:05.853Z
Answers.Text: @Tinkeringbell That is how I got the much smaller test-piece I'm currently experimenting with. The glue is softening and slightly dissolving now (after about 5 hours) but it is just the top-layer and goes very slowly. Lack of penetration seems to be the biggest problem.
Answers.UserDisplayName: Tonny
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-06-02T12:03:14.457Z
Answers.Text: @Tonny yeah, it can probably take a long time before the insides of the clump reach 40 degrees, if you're soaking something in water that's about ~40 degrees at the start of each half hour, so for any glue you can cut/shave away, that's going to speed up the process a bit. But it's nice to read it *is* working!
Answers.UserDisplayName: Tinkeringbell
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-06-02T21:32:38.620Z
Answers.Text: @Tonny do you happen to have a sous vide machine (a cooking device)?  It allows precise temperature control and will maintain the water at a desired temperature.
Answers.UserDisplayName: Kirk Woll
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-06-03T07:23:59.433Z
Answers.Text: @KirkWoll I don't. Those things are rare beasts outside of restaurants. Would in this case be highly useful.
Answers.UserDisplayName: Tonny
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-06-08T15:59:16.697Z
Answers.Text: If doing it with water, I'd go for volume rather than trying to keep it really hot - like a large plastic crate  that could be left somewhere warm, and leave it for several days, maybe stirring every few hours
Answers.UserDisplayName: Chris H
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-06-01T22:48:05.713Z
Answers.LastActivityDate: 2021-06-07T15:46:58.280Z
Answers.LastEditDate: 2021-06-07T15:46:58.280Z
Answers.UserDisplayName: D M
Answers.Body: <p>Self-answer to let you all know how things went.</p>
  <p>Warm water was having some effect but it took forever. So Saturday morning I went to the DIY store and got myself a 5 liter jerrycan of white vinegar.</p>
  <p>Taking my small test-clump I dropped it in a a bucket with a 50/50 mix of warm water and vinegar. In about 5 minutes the top 2-3 millimeter of the glue had turned in a slimy gooey layer. Rinsing that of with a brush and exposing the still solid glue underneath started the dissolve the glue underneath as well.</p>
  <p>Took less than 15 minutes to break up the whole clump and to brush the Lego pieces more or less clean. The more I could break up the clump the quicker it went.
  After that I gave them a second rinse in another bucket with water/vinegar mix just to get rid of the remaining residue and finally rinsed them off under running tap-water.</p>
  <p>The first bucket now contained a very nasty slimy water/vinegar/glue mix.<br />
  I threw that away and refilled with fresh warm water/vinegar.<br />
  Stuck the large clump in (it was too large to submerge completely, part of it stuck above water) and let it soak for another 10 minutes.<br />
  Was then able to break up the under-water section in smaller pieces so eventually I was able to get everything soaking.</p>
  <p>After another 10 minutes I had broken up the entire clump into small clumps each containing maybe 10 to 15 Lego pieces. Left these to soak some more.<br />
  Another 15 minutes later I had freed all Lego pieces and just needed to brush/rinse the remaining goo off.</p>
  <p>Conclusion: Vinegar worked really well. Mixing it with warm water might have somewhat sped up the process as well.<br />
  There doesn't seem to be any negative impact on the Lego bricks.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-06-07T13:40:34.120Z
Answers.Text: Great to hear all went that quick. I just wonder if vinegar had any, solvent like, impact. Did any of elements develop matte finish, which wasn't present before?
Answers.UserDisplayName: Alex
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-06-07T14:07:32.093Z
Answers.Text: @Alex No, no visible effect as far as I can tell. No discoloration, no loss of gloss and surface texture of the bricks feels exactly as non-treated bricks. I did have some minor scratching but that was the rather hard brush I used at first. Switched to a much softer brush later.
Answers.UserDisplayName: Tonny
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-06-07T13:01:02.613Z
Answers.LastActivityDate: 2021-06-07T14:45:38.013Z
Answers.LastEditDate: 2021-06-07T14:45:38.013Z
Answers.UserDisplayName: Tonny
Body: <p>A friend of mine gave me a large crate of Lego that he found in the house he just bought.<br />
  It appears to be several sets from the late 70's. (I spotted the building instructions for the 850 and 851 Technic sets in there.)</p>
  <p>Unfortunately that crate also contained a bunch of other stuff, including a large plastic squirt-bottle of PVA wood glue. The bottle burst open and the glue leaked into some of the Lego.<br />
  I have about 500 bricks fused together with several booklets of building instructions into a sort of modern sculpture.</p>
  <p>I would like to get the glue off, without destroying the bricks, but this glue has been there for 30, maybe 40 years.</p>
  <p>The usual approach for dissolving old PVA glue is soaking it with hot water, white vinegar or methylated spirits (in order of aggressiveness).</p>
  <p>But would that be safe for the Lego?<br />
  As far as I know hot water, if too hot, might soften/deform Lego bricks.<br />
  Methylated spirits is, in general, not safe to use on plastics and will probably affect the plastic used in Lego bricks.<br />
  White vinegar is, as far as I know, safe to use on Lego.</p>
  <p>So I'm thinking of just soaking everything in warm water (say 40 degrees Celsius) for a couple of days and seeing how that goes. If that doesn't dissolve the glue I can try again with white vinegar.</p>
  <p>Does anyone see a problem with that? Does anyone know a better way of doing this?</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-06-02T07:10:28.200Z
Comments.Text: Can you provide a picture of the "sculpture"? Maybe it is better to leave it like that instead of having some damaged bricks and instructions.
Comments.UserDisplayName: Metalbeard
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-06-02T09:42:54.383Z
Comments.Text: @Aziraphale It doesn't look attractive in any way. Just a very irregular blob of mostly hardened white/semi-transparant glue, paper and parts of Lego bricks sticking out. There is also a hairbrush stuck into the blob. My main interest is the bricks as some appear to be very hard to get pieces that I actually need. Like 966a ramp for trailer base in blue and yellow. I have one of those each, but both are broken and I can see there are 2 yellows and 1 blue in the blob that look, as far as I can tell, to be undamaged.
Comments.UserDisplayName: Tonny
Tags: <cleaning><disassembly><glue>
Title: Remove 3, maybe 4, decades old PVA glue from Lego
UserDisplayName: Tonny
ThreadText: # Remove 3, maybe 4, decades old PVA glue from Lego
  
  (Asked by: username_0 on 2021-06-01)
  
  A friend of mine gave me a large crate of Lego that he found in the house he just bought.  
  It appears to be several sets from the late 70's. (I spotted the building instructions for the 850 and 851 Technic sets in there.)
  
  Unfortunately that crate also contained a bunch of other stuff, including a large plastic squirt-bottle of PVA wood glue. The bottle burst open and the glue leaked into some of the Lego.  
  I have about 500 bricks fused together with several booklets of building instructions into a sort of modern sculpture.
  
  I would like to get the glue off, without destroying the bricks, but this glue has been there for 30, maybe 40 years.
  
  The usual approach for dissolving old PVA glue is soaking it with hot water, white vinegar or methylated spirits (in order of aggressiveness).
  
  But would that be safe for the Lego?  
  As far as I know hot water, if too hot, might soften/deform Lego bricks.  
  Methylated spirits is, in general, not safe to use on plastics and will probably affect the plastic used in Lego bricks.  
  White vinegar is, as far as I know, safe to use on Lego.
  
  So I'm thinking of just soaking everything in warm water (say 40 degrees Celsius) for a couple of days and seeing how that goes. If that doesn't dissolve the glue I can try again with white vinegar.
  
  Does anyone see a problem with that? Does anyone know a better way of doing this?
  
  **Tags:** cleaning, disassembly, glue
  > **Comments:**
  > **username_1**: Can you provide a picture of the "sculpture"? Maybe it is better to leave it like that instead of having some damaged bricks and instructions.  
  > **username_0**: @Aziraphale It doesn't look attractive in any way. Just a very irregular blob of mostly hardened white/semi-transparant glue, paper and parts of Lego bricks sticking out. There is also a hairbrush stuck into the blob. My main interest is the bricks as some appear to be very hard to get pieces that I actually need. Like 966a ramp for trailer base in blue and yellow. I have one of those each, but both are broken and I can see there are 2 yellows and 1 blue in the blob that look, as far as I can tell, to be undamaged.  
  
  ---
  
  ## 2 answers
  
  ### Answer by username_0 on 2021-06-07. Score: 13 | Accepted answer
  
  Self-answer to let you all know how things went.
  
  Warm water was having some effect but it took forever. So Saturday morning I went to the DIY store and got myself a 5 liter jerrycan of white vinegar.
  
  Taking my small test-clump I dropped it in a a bucket with a 50/50 mix of warm water and vinegar. In about 5 minutes the top 2-3 millimeter of the glue had turned in a slimy gooey layer. Rinsing that of with a brush and exposing the still solid glue underneath started the dissolve the glue underneath as well.
  
  Took less than 15 minutes to break up the whole clump and to brush the Lego pieces more or less clean. The more I could break up the clump the quicker it went.
  After that I gave them a second rinse in another bucket with water/vinegar mix just to get rid of the remaining residue and finally rinsed them off under running tap-water.
  
  The first bucket now contained a very nasty slimy water/vinegar/glue mix.  
  I threw that away and refilled with fresh warm water/vinegar.  
  Stuck the large clump in (it was too large to submerge completely, part of it stuck above water) and let it soak for another 10 minutes.  
  Was then able to break up the under-water section in smaller pieces so eventually I was able to get everything soaking.
  
  After another 10 minutes I had broken up the entire clump into small clumps each containing maybe 10 to 15 Lego pieces. Left these to soak some more.  
  Another 15 minutes later I had freed all Lego pieces and just needed to brush/rinse the remaining goo off.
  
  Conclusion: Vinegar worked really well. Mixing it with warm water might have somewhat sped up the process as well.  
  There doesn't seem to be any negative impact on the Lego bricks.
  
  > **Comments:**
  > **username_3**: Great to hear all went that quick. I just wonder if vinegar had any, solvent like, impact. Did any of elements develop matte finish, which wasn't present before?  
  > **username_0**: @Alex No, no visible effect as far as I can tell. No discoloration, no loss of gloss and surface texture of the bricks feels exactly as non-treated bricks. I did have some minor scratching but that was the rather hard brush I used at first. Switched to a much softer brush later.  
  
  ---
  
  ### Answer by username_2 on 2021-06-01. Score: 16
  
  Take it for what it is, I am not a material scientist and this is not a guarantee that the following information will work in your case.
  
  ---
  
  I believe your approach is correct, or at least as good as you'll be able to get considering the material properties of the bricks and the glue.
  
  LEGO bricks are [made of ABS plastic](https://en.wikipedia.org/wiki/Lego) (at least after 1963).
  
  According to data from the Cole-Parmer [Chemical Compatibility Database](https://www.coleparmer.com/Chemical-Resistance), ABS plastic is very susceptible to damage from nearly all the normal solvents used to remove PVA glue.
  
  | Chemical | Compatibility with ABS plastic |
  | --- | --- |
  | [Acetone](https://www.coleparmer.com/Search?searchterm=Acetone) | D - Severe Effect: Not recommended for any use. |
  | [Methanol (Methyl Alcohol)](https://www.coleparmer.com/Search?searchterm=Methanol%20(Methyl%20Alcohol)) | D - Severe Effect: Not recommended for any use. |
  | [Vinegar](https://www.coleparmer.com/Search?searchterm=Vinegar) | A - Excellent |
  
  Vinegar looks like it may work, especially if you expose the glue to soften it before attempting to remove it from the bricks. Unfortunately, the instructions are almost certainly beyond saving.
  
  Concerning heat, ABS [appears to be safe](https://en.wikipedia.org/wiki/Acrylonitrile_butadiene_styrene) until around 80°C (176°F) when it starts to deform. This is good considering [PVA softens as early as 30°C (86°F)](https://www.sciencedirect.com/topics/chemical-engineering/polyvinyl-acetate). However, as Alex points out, [LEGO recommends using water no warmer than 40°C (104°F)](https://bricks.stackexchange.com/a/100/17802).
  
  You might try submerging the LEGO-berg in hot water for an extended period of time (articles I found suggested multiple hours, changing the water as needed) then using a syringe or spray bottle to apply vinegar to one area at a time. With some force, the weakened glue should release. Assuming it has weakened sufficiently, wiping with a course cloth should remove the residue.
  
  It is unclear in my searching whether time is a significant factor in the susceptibility of PVA glue to heat. It is a resin, so there may be some long-term curing that prevents the glue from re-softening, but I couldn't find a definitive source one way or the other.
  
  As an additional consideration, exposure to extended heat, chemical treatments, and physical cleaning may impact the surface quality of your bricks. Additionally, if the solvents present in the glue when it was applied to the surface also affect ABS, the glue may be bonded to the structure of the brick, not just the surface. If this is the case, you will not be able to salvage the brick without a destructive process like sanding that will inevitably leave signs.
  
  If you can identify a small chunk of bricks to test the process on, you can at least see if heat and vinegar are a potential solution for the rest of your bricks.
  
  > **Comments:**
  > **username_3**: 80°C? Well, LEGO recommends using temperature no more than 40°C when washing bricks. I wouldn't use liquids much warmer than that. And in case there are any CA bricks they will deform under any warmer temperature (if they haven't deformed yet).  
  > **username_0**: Up to 40 Celsius is fine. I have washed Lego in the washing machine on the 40 degree program before. (Take a pillowcase. Load with Lego. Tie it very securely shut and wash on the 40 degree fine cloth program without using the centrifuge.)  
  > **username_0**: I'm having a small fist-size clump with about 20 bricks in it currently sittng in hot water (tap-water, as hot as I can stand to stick my hand in. Should be around 40 degrees). Will replace the water every 30 minutes or so. Been doing this for 2 hours now. So far the glue doesn't appear to be softening at all. I'll let it work in for a day or 2. After that I will try vinegar.  
  > **username_4**: @Tonny please update us on how it went!  
  > **username_0**: @htmlcoderexe I will write a self-answer with a progress report. Will probably be in the weekend as I have to make a business trip tomorrow and Friday.  
  > **username_4**: Sweet, good luck with the bricks and with the trip!  
  > **username_5**: @Tonny one other thing you could consider with large clumps like this, is to see if it's possible to increase the surface area that's exposed to heat/liquid. If you have a bit of knife skills and the clumps allow it, you could try using a sharp blade to cut the large clumps into several smaller ones (increasing the surface area), or even shave off as much of the glue as possible before applying any water/vinegar, which can save a few rounds of soaking because you're now directly heating/soaking the inner layers of glue.  
  > **username_0**: @Tinkeringbell That is how I got the much smaller test-piece I'm currently experimenting with. The glue is softening and slightly dissolving now (after about 5 hours) but it is just the top-layer and goes very slowly. Lack of penetration seems to be the biggest problem.  
  > **username_5**: @Tonny yeah, it can probably take a long time before the insides of the clump reach 40 degrees, if you're soaking something in water that's about ~40 degrees at the start of each half hour, so for any glue you can cut/shave away, that's going to speed up the process a bit. But it's nice to read it *is* working!  
  > **username_6**: @Tonny do you happen to have a sous vide machine (a cooking device)?  It allows precise temperature control and will maintain the water at a desired temperature.  
  > **username_0**: @KirkWoll I don't. Those things are rare beasts outside of restaurants. Would in this case be highly useful.  
  > **username_7**: If doing it with water, I'd go for volume rather than trying to keep it really hot - like a large plastic crate  that could be left somewhere warm, and leave it for several days, maybe stirring every few hours  
  
  ---
  
  