Jump to content
Model Cars Magazine Forum

100% Lye yellowing?


Recommended Posts

So i use super clean for stripping chrome parts and it works great, but i end up wasting a whole gallon of it after it's used up.  So i figured with it have lye in it i would get some lye and try out on some test parts.  Basically the lye takes the chrome off in a matter of seconds, but takes even longer to take off the under coating.  So after leaving it in the lye for a whole day - the undercoating was gone, but the part is stained a light yellow looking where all the under coating was left at.  Looks kind of weird and i wish now i would of took a picture of it.  Seems the 100% lye needs something with it to clean along side of it.  1Ib of lye was $6 and gallon of super clean is $9, and i figured the lye would last much longer, but if this issue is what happens I'll stick with super clean.

Link to comment
Share on other sites

The clear undercoat for the "chrome" is usually light amber color, and the plastic is usually whatever color they were using for molding the kit during that run.  You mentioned that the clear coat was stripped (which is as expected considering you used Lye).
Is it possible that the bare plastic used for the "chromed" parts was naturally yellow to begin with?
If the part are still on the tree, scrape the top layer of the bare plastic on one the runners (some call it "sprue") to see of the yellow color is only on the surface.

 

Also, be really careful when working with Lye (by itself, or in other fluids that contain it)-- it will attack your skin and eyes!

Edited by peteski
  • Like 1
Link to comment
Share on other sites

1 hour ago, peteski said:

The clear undercoat for the "chrome" is usually light amber color, and the plastic is usually whatever color they were using for molding the kit during that run.  You mentioned that the clear coat was stripped (which is as expected considering you used Lye).
Is it possible that the bare plastic used for the "chromed" parts was naturally yellow to begin with?
If the part are still on the tree, scrape the top layer of the bare plastic on one the runners (some call it "sprue") to see of the yellow color is only on the surface.

 

Also, be really careful when working with Lye (by itself, or in other fluids that contain it)-- it will attack your skin and eyes!

I'll have to do some more testing or maybe i used to much lye in the water.  Some of the chrome parts are like half white and half of the stained yellow after scrubbing.  Never had this issue using just super clean.  I'm gonna do some more test parts and take some pictures, but to better explain the look - it's looks like how old decals get with the faded yellow look.  Maybe it could just be the chrome parts itself like you said? I'll check again tomorrow. 

Link to comment
Share on other sites

3 hours ago, Dpate said:

I'll have to do some more testing or maybe i used to much lye in the water.  Some of the chrome parts are like half white and half of the stained yellow after scrubbing.  Never had this issue using just super clean.  I'm gonna do some more test parts and take some pictures, but to better explain the look - it's looks like how old decals get with the faded yellow look.  Maybe it could just be the chrome parts itself like you said? I'll check again tomorrow. 

The plastic under plated parts is often stained yellow by the lacquer undercoat itself, so the lye may not be causing the problem.

As long as it's not damaging the parts, try it a few more times on parts from various kits.

If only some of them have the staining, it's the undercoat, and not the lye.

I've noticed the same phenomenon with Super Clean and other products, so when it happens, I just chalked it up to undercoat staining.

 

As Peter stated, it might just be the plastic under the chrome as well.

As you can see from these valve covers that were stripped of their chrome, they are very yellow.

But, if you look closely, the plastic on the inside of the hole that I drilled for the oil filler cap is the same color, indicating that the plastic is that color through and through.

 

A little yellowing on the part is really not going to hurt anything anyway if you're going to paint or re-plate.

 

image.jpeg.fa6e8a0912a5ac055ea08bdd2067eea1.jpeg

 

 

 

 

Steve

Edited by StevenGuthmiller
  • Like 1
Link to comment
Share on other sites

16 hours ago, Dpate said:

So i use super clean for stripping chrome parts and it works great, but i end up wasting a whole gallon of it after it's used up.  So i figured with it have lye in it i would get some lye and try out on some test parts.  Basically the lye takes the chrome off in a matter of seconds, but takes even longer to take off the under coating.  So after leaving it in the lye for a whole day - the undercoating was gone, but the part is stained a light yellow looking where all the under coating was left at.  Looks kind of weird and i wish now i would of took a picture of it.  Seems the 100% lye needs something with it to clean along side of it.  1Ib of lye was $6 and gallon of super clean is $9, and i figured the lye would last much longer, but if this issue is what happens I'll stick with super clean.

As for throwing away your Super Clean after one use. Consider straining the Super Clean before pouring it back into the container. I use a small colander like you would use for Tea as a strainer. I'm sure you have noticed the removed paint or chrome at the bottom of your container after cleaning a part, This is the stuff you don't want back in the container. There will always be a small amount of contaminates getting back into your container but it would be minimal. I have done this for years before I felt the Super Clean was no longer effective.  This would all depend on how often your are using it.  

  • Like 1
Link to comment
Share on other sites

34 minutes ago, iBorg said:

When I return the super clean to the contaner, I use a coffee filter to strain it with.

Just be sure you don't get the filters mixed up; could make for some mighty toxic coffee.  I also have a strainer I use.  It looks similar to a funnel but the bottom is a really fine mesh.  I place it in the funnel I use to return the SC to the jug; it will remove 90%+ of the contaminants and it helps me find those really small pieces I forgot I put in the strip tank.

Link to comment
Share on other sites

5 hours ago, espo said:

As for throwing away your Super Clean after one use. Consider straining the Super Clean before pouring it back into the container. I use a small colander like you would use for Tea as a strainer. I'm sure you have noticed the removed paint or chrome at the bottom of your container after cleaning a part, This is the stuff you don't want back in the container. There will always be a small amount of contaminates getting back into your container but it would be minimal. I have done this for years before I felt the Super Clean was no longer effective.  This would all depend on how often your are using it.  

Well when i use it i keep it in a 2 gallon plastic container with locking lid.  I put whole entire chrome tree's into it, works amazing when it's fresh.  I can tell it's getting used up because it takes a whole lot longer to strip anything - like sometimes it gets so weak it wont even touch the chrome.  So straining it i don't think would do any good if the stripping properties are already used up.  Could i put the lye into the super clean considering it already has it in there or putting 100% lye into a chemical like that is a bad idea?

Link to comment
Share on other sites

I don't know, maybe I don't use my Super Clean as much as others do, but I've got about a half a gallon in a rectangular plastic food container and I haven't changed it in at least a year and a half, probably longer.

It's most likely beginning to weaken, but it still works fine, even for removing lacquer paint.

 

 

 

 

Steve

Link to comment
Share on other sites

1 hour ago, peteski said:

Could those spots be remains of the clear undercoat?  Either way, I don't think the lye cause that.  Whatever it is, I don't think I would worry about it.

No i don't think its the clear undercoat -that's 100% gone.  Just looks stained.  This is after sitting in the lye for 2 days. So it's got to be just the parts itself so I'm probably gonna put a nice white part from a RIP kit and let it sit in the lye for 2 days and see what happens.  I think the lye is 100% safe so after i use up this new gallon of super clean I'm gonna stick with the 100% lye.  It works even faster than the super clean, and it's pretty amazing to watch it eat away the chrome in a matter of seconds lol.  

Link to comment
Share on other sites

12 minutes ago, peteski said:

The "chrome" in model kits is actually very thin layer of aluminum.  If you want to have some fun, drop a tiny piece of standard aluminum foil in the lye solution.

hmmmm....Interesting.  Will do lol

Link to comment
Share on other sites

On 10/14/2021 at 3:57 PM, Dpate said:

Well when i use it i keep it in a 2 gallon plastic container with locking lid.  I put whole entire chrome tree's into it, works amazing when it's fresh.  I can tell it's getting used up because it takes a whole lot longer to strip anything - like sometimes it gets so weak it wont even touch the chrome.  So straining it i don't think would do any good if the stripping properties are already used up.  Could i put the lye into the super clean considering it already has it in there or putting 100% lye into a chemical like that is a bad idea?

I don't think I would mix the lye. Just me 

If the super clean is used straight it should be good for a long time. I have used an old t-shirt/rag at the bottom of a strainer to clean out the old paint flakes.  If it was cold when you tried to strip the paint or chrome off the parts it does take longer.  at my house (in Michigan) the jug stays in the basement until I need to strip something. I like to have the jug around 70 degrees or warmer for better action. Looks like you live in a warmer area though.  

 

Link to comment
Share on other sites

True, full strength Lye solution is a very caustic chemical. Just as it will eat all the BLAH_BLAH_BLAH_BLAH in the sewer pipes, it will happily eat human skin and eyes.  Be very careful with Lye.  If you use it, follow the instructions on the container how to properly mix it with water.

Link to comment
Share on other sites

6 hours ago, 1930fordpickup said:

I don't think I would mix the lye. Just me 

If the super clean is used straight it should be good for a long time. I have used an old t-shirt/rag at the bottom of a strainer to clean out the old paint flakes.  If it was cold when you tried to strip the paint or chrome off the parts it does take longer.  at my house (in Michigan) the jug stays in the basement until I need to strip something. I like to have the jug around 70 degrees or warmer for better action. Looks like you live in a warmer area though.  

 

Yeah i was thinking of putting a heater like you would use in a fish tank into the container and have it set for 70F to keep  it heated.  Good idea or no?  Would that work for the lye too heating it up?

2 hours ago, peteski said:

True, full strength Lye solution is a very caustic chemical. Just as it will eat all the BLAH_BLAH_BLAH_BLAH in the sewer pipes, it will happily eat human skin and eyes.  Be very careful with Lye.  If you use it, follow the instructions on the container how to properly mix it with water.

Well the instructions on the bottle just explain how to add it to a drain.  I just add it to the water very slowly and mix it using a plastic spoon and avoiding any splashing.  

2 hours ago, Rick L said:

Why the concern? Can’t you just prime and paint over it?

Yes.  The only concern I've had was if the lye was causing any issue/damage that's all.  Seems it's not so think I'm good to go.

Edited by Dpate
Link to comment
Share on other sites

I don't know If I would use a fish tank heater. That requires motion to heat the tank properly. I wonder if adding an air pump might work?  As long as you are at room temp it works fine. Someone mentioned using an ultrasonic cleaner to strip parts on here a long time ago, and some of those have heaters. Don't over think this to much. I do all the time and it just slows me down.  

BTW If Steve says they look fine and paint away. Do just that, His work is awesome. 

Edited by 1930fordpickup
Link to comment
Share on other sites

4 minutes ago, 1930fordpickup said:

I don't know If I would use a fish tank heater. That requires motion to heat the tank properly. I wonder if adding an air pump might work?  As long as you are at room temp it works fine. Someone mentioned using an ultrasonic cleaner to strip parts on here a long time ago, and some of those have heaters. Don't over think this to much. I do all the time and it just slows me down.  

BTW If Steve says they look fine and paint away. Do just that, His work is awesome. 

Gotcha and thanks for the help as everyone else.  Also yes i hope to get to his level one day.

Link to comment
Share on other sites

44 minutes ago, Dpate said:

Gotcha and thanks for the help as everyone else.  Also yes i hope to get to his level one day.

If you try something different please post results good and bad. Good information on what to do and what not to do is always welcome on here.  

Link to comment
Share on other sites

On 10/14/2021 at 6:02 PM, StevenGuthmiller said:

I don't know, maybe I don't use my Super Clean as much as others do, but I've got about a half a gallon in a rectangular plastic food container and I haven't changed it in at least a year and a half, probably longer.

It's most likely beginning to weaken, but it still works fine, even for removing lacquer paint.

Same here. Mine might be even older. It's filthy, but the only weakening I've noticed is, it seems to take about three times as long to strip paint when it's cold. (I keep the tub in the garage.) 

 

19 hours ago, peteski said:

If you want to have some fun, drop a tiny piece of standard aluminum foil in the lye solution.

I'll save you some misery, as I once tried to mask a painted area I wanted to save with aluminum foil and sprayed the rest of the model with Easy-Off: DON'T mix lye and aluminum unless you just love the smell of rotten eggs! :blink::wacko::angry:

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...