I've stripped some aluminum trim the last few years and went through the usual recommendations on forums and the Internet starting with HD Easy Off Oven Cleaner. Don't do it - eats the heck out of aluminum and works very uneven. The surface often looked ridiculously rough. I had to start out as coarse as 120 sandpaper on particularly rough pieces and work all the way down to 2500 or so which was very time consuming and tedious.
Then I went to Greased Lightning which was less aggressive on aluminum but required the trim to be immersed in it for hours requiring a trough for big parts or some PVC pipe for straight trim pieces. Worked fairly well but not always uniformly. Problem was the Greased lightning was only good for a one time use so I went through a lot of it which ran expenses up and then I had the problem with what to do with all of it once used. I dumped a lot on my driveway to evaporate and still have some in storage in my storage building.
This time I decided to try powdered Lye or Sodium Hydroxide. A two pound bottle at the hardware store is pretty cheap and will last a long time.
I stripped a trunk panel in a metal through I have and 4 pieces of straight trim in a 2" PVC pipe. I mixed up a gallon with 16 teaspoons of lye and poured it in the 2" pipe and put 3 pieces of trim in. This was a pretty hot mix and bubbled aggressively as it heated up, bubbled like it was boiling, and stripped away. After about 1 hour the trim was stripped clean, was pretty uniform and was pretty smooth.
Today I stripped the tail panel and poured the left over 1 gallon in and then mixed up 3 more gallons with 10 teaspoons of lye in each in the trough.
This was probably just a little on the weak side as it turned out but after an hour and ten minutes the panel was mostly stripped. The surface was still pretty slick and shiny in areas after cleaning off the black scum and there may have been a very thin coat of anodizing left. But a couple swipes of 600 grit sandpaper and it was obviously into aluminum. I think there is a very, very thin layer of soft anodizing left but the metal is still real smooth and it's so thin it will immediately sand off. I can probably start with 600 except where there may be some scratches or dings to fix. Sanding the aluminum is necessary to get rid of most of the pits, scratches, hide ding and dent repairs. In the past I've usually sanded down to 2500 and then use a 3000 3M Trizact pad on it. By that time it can usually just be hit with Mothers Aluminum Polish or run it over my buffer wheel on my bench grinder with a white aluminum compound and soft flannel buffer wheel. But how smooth the lye left the surface is the big plus to this method, as is the low cost and more uniform removal action.
In hindsight I probably should have used a little stronger mix than the 10 teaspoons/gallon. the 16 teaspoons seemed a little hot so maybe a happy medium is around 12/13 teaspoons/gallon. It may depend on the air temperature and it in a confined container like PVC pipe or an open container like my trough. You kind of need to monitor the part as you go to see how it's coming. I wiped the smudging off and hit a small area with a piece of 600 sandpaper and if it sanded easy and appeared to get down to fresh aluminum immediately I figured it was done.
Hope someone can use this info.
Then I went to Greased Lightning which was less aggressive on aluminum but required the trim to be immersed in it for hours requiring a trough for big parts or some PVC pipe for straight trim pieces. Worked fairly well but not always uniformly. Problem was the Greased lightning was only good for a one time use so I went through a lot of it which ran expenses up and then I had the problem with what to do with all of it once used. I dumped a lot on my driveway to evaporate and still have some in storage in my storage building.
This time I decided to try powdered Lye or Sodium Hydroxide. A two pound bottle at the hardware store is pretty cheap and will last a long time.
I stripped a trunk panel in a metal through I have and 4 pieces of straight trim in a 2" PVC pipe. I mixed up a gallon with 16 teaspoons of lye and poured it in the 2" pipe and put 3 pieces of trim in. This was a pretty hot mix and bubbled aggressively as it heated up, bubbled like it was boiling, and stripped away. After about 1 hour the trim was stripped clean, was pretty uniform and was pretty smooth.
Today I stripped the tail panel and poured the left over 1 gallon in and then mixed up 3 more gallons with 10 teaspoons of lye in each in the trough.
This was probably just a little on the weak side as it turned out but after an hour and ten minutes the panel was mostly stripped. The surface was still pretty slick and shiny in areas after cleaning off the black scum and there may have been a very thin coat of anodizing left. But a couple swipes of 600 grit sandpaper and it was obviously into aluminum. I think there is a very, very thin layer of soft anodizing left but the metal is still real smooth and it's so thin it will immediately sand off. I can probably start with 600 except where there may be some scratches or dings to fix. Sanding the aluminum is necessary to get rid of most of the pits, scratches, hide ding and dent repairs. In the past I've usually sanded down to 2500 and then use a 3000 3M Trizact pad on it. By that time it can usually just be hit with Mothers Aluminum Polish or run it over my buffer wheel on my bench grinder with a white aluminum compound and soft flannel buffer wheel. But how smooth the lye left the surface is the big plus to this method, as is the low cost and more uniform removal action.
In hindsight I probably should have used a little stronger mix than the 10 teaspoons/gallon. the 16 teaspoons seemed a little hot so maybe a happy medium is around 12/13 teaspoons/gallon. It may depend on the air temperature and it in a confined container like PVC pipe or an open container like my trough. You kind of need to monitor the part as you go to see how it's coming. I wiped the smudging off and hit a small area with a piece of 600 sandpaper and if it sanded easy and appeared to get down to fresh aluminum immediately I figured it was done.
Hope someone can use this info.
