There?s been a fair amount of discussion here about Sanchem 6100. I just started with it yesterday, but wanted to share my observations so far.
I finally finished all of the deburring and match-drilling of all the horizontal and vertical stabilizer parts. I had ordered Sanchem?s 6100 A/B/C and Sealer #2 for corrosion protection. I decided to use Sanchem based on a bunch of factors, including minimizing exposure to hazardous chemicals, ability to use in cooler temps (garage in MN in winter), claimed good corrosion protection, minimal concern for paint adhesion on interior surfaces, ease of use, lack of experience with spray equipment, easy disposal, etc.
So yesterday I started cleaning each part with the Part C cleaner and scotchbrite pads, rinsing in distilled water, then dunking and/or wiping with the 50/50 mix of the Part A & B chemicals for 3-5 minutes, then rinsing again with distilled water. I had mixed results in terms of uniformity of color even on individual pieces. Some areas appeared to change color very little with other areas turning a light golden color. I tried prepping the parts differently to see if I could achieve better results, including cleaning/scrubbing more, refreshing the chemicals, longer dunking, but didn?t get a noticeable improvement. Now that the parts have fully dried the overall color change appears more uniform, but is a very light silver/gold color. Perhaps this is normal, I was just expecting a more distinct golden color.
As I?m a little puzzled about the result so far, I decided to make a test piece. I took a scrap sheet of aluminum and sanded the Alclad off one side, then did the Sanchem A/B/C treatment on two-thirds of each side. I then applied a light coat of the Sealer #2 to half of the treated portions on each side and heated it using a heat gun to make the sealer clear, per the instructions. Interestingly, the sealer made the light gold color from the A/B/C treatment disappear, which I can only assume is supposed to happen.
I then wet the pieces and observed water beading up nicely on the Alclad portions as well as the portion with the Sealer #2. Water sheets on the sanded and A/B/C treatment only portions. I wrapped the piece in a paper towel soaked with a salt solution and will wet and dry like this over the next week or two to see if any corrosion occurs. I doubt it will occur in this timeframe, but it will be interesting if it does and I?ll update here if anything happens.
So anyways, still puzzled, I did some more searching on the web and came up with a paper detailing some extensive corrosion and adhesion test results of a number of non-chromate aluminum treatments, including Sanchem 7000, comparing them to Alodine.
The full paper is available at: http://www.industrialanodizing.com/Documents/ncapi.pdf
I?d encourage those interested to read the report, however selected text from the report includes:
1. Section 3.9 of the report states that ?Sanchem 7000 with the sealer has historically demonstrated unacceptable paint adhesion.?
2. Table 3.1 of the report states ?Minimal corrosion inhibition without sealer. Sealer requires elevated temperature cure and has poor adhesion characteristics.?
3. Section 5.1.2 of the report states that "Alodine 1200S and TCP coatings exposed to 1-week and 2-week Neutral Salt Fog Exposure show no corrosion on 2024-T3, 7075-T6, and 5083-H131. Alodine 5200 and Sanchem 7000 with Seal #2 show surface corrosion within 48 hours on 2024-T3?
My comments based on what I?ve read and experienced so far include:
1. The Sanchem products appear to offer some corrosion protection, but generally not equivalent to Alodine.
2. No comparison of Sanchem?s products to other systems (bare Alclad, epoxy primers, etc.) is available so it?s hard to compare to other systems.
3. The Sanchem products do require the Sealer to provide corrosion protection, whereas the Alodine performed well without any additional protection/coating.
4. Any additional primers/sealers/paints applied over the Sealer may not adhere well.
So where does this leave me? Thoughts/concerns include:
1. Due to the resulting clear color of the sealed surfaces, it will likely be difficult to see any areas where the protection has been damaged during assembly/riveting.
2. Sealer is clearly a must to achieve any corrosion protection, but aren?t some internal components painted with the exterior (e.g. rear of HS/VS spars, outside ribs, etc)? Adhesion problems?
3. When using the scotchbrite pads when cleaning with the Part C chemical is the diminished corrosion-proofing from the Alclad offset by the protection from the Sanchem system?
4. Applying the A/B/C pretreatments took a fair amount of time, and I didn?t do the skins and haven?t applied the sealer to anything yet.
5. Should I switch to an epoxy primer which I believe will be faster, simpler, and more reliable?
6. Should I stop worrying incessantly about these details and just get it done?
Anyways, I just thought I?d share what I?ve learned so far. If anyone has any other results with the Sanchem chemicals please post them.
Thanks,
Mike Behnke
RV-9A Empennage
I finally finished all of the deburring and match-drilling of all the horizontal and vertical stabilizer parts. I had ordered Sanchem?s 6100 A/B/C and Sealer #2 for corrosion protection. I decided to use Sanchem based on a bunch of factors, including minimizing exposure to hazardous chemicals, ability to use in cooler temps (garage in MN in winter), claimed good corrosion protection, minimal concern for paint adhesion on interior surfaces, ease of use, lack of experience with spray equipment, easy disposal, etc.
So yesterday I started cleaning each part with the Part C cleaner and scotchbrite pads, rinsing in distilled water, then dunking and/or wiping with the 50/50 mix of the Part A & B chemicals for 3-5 minutes, then rinsing again with distilled water. I had mixed results in terms of uniformity of color even on individual pieces. Some areas appeared to change color very little with other areas turning a light golden color. I tried prepping the parts differently to see if I could achieve better results, including cleaning/scrubbing more, refreshing the chemicals, longer dunking, but didn?t get a noticeable improvement. Now that the parts have fully dried the overall color change appears more uniform, but is a very light silver/gold color. Perhaps this is normal, I was just expecting a more distinct golden color.
As I?m a little puzzled about the result so far, I decided to make a test piece. I took a scrap sheet of aluminum and sanded the Alclad off one side, then did the Sanchem A/B/C treatment on two-thirds of each side. I then applied a light coat of the Sealer #2 to half of the treated portions on each side and heated it using a heat gun to make the sealer clear, per the instructions. Interestingly, the sealer made the light gold color from the A/B/C treatment disappear, which I can only assume is supposed to happen.
I then wet the pieces and observed water beading up nicely on the Alclad portions as well as the portion with the Sealer #2. Water sheets on the sanded and A/B/C treatment only portions. I wrapped the piece in a paper towel soaked with a salt solution and will wet and dry like this over the next week or two to see if any corrosion occurs. I doubt it will occur in this timeframe, but it will be interesting if it does and I?ll update here if anything happens.
So anyways, still puzzled, I did some more searching on the web and came up with a paper detailing some extensive corrosion and adhesion test results of a number of non-chromate aluminum treatments, including Sanchem 7000, comparing them to Alodine.
The full paper is available at: http://www.industrialanodizing.com/Documents/ncapi.pdf
I?d encourage those interested to read the report, however selected text from the report includes:
1. Section 3.9 of the report states that ?Sanchem 7000 with the sealer has historically demonstrated unacceptable paint adhesion.?
2. Table 3.1 of the report states ?Minimal corrosion inhibition without sealer. Sealer requires elevated temperature cure and has poor adhesion characteristics.?
3. Section 5.1.2 of the report states that "Alodine 1200S and TCP coatings exposed to 1-week and 2-week Neutral Salt Fog Exposure show no corrosion on 2024-T3, 7075-T6, and 5083-H131. Alodine 5200 and Sanchem 7000 with Seal #2 show surface corrosion within 48 hours on 2024-T3?
My comments based on what I?ve read and experienced so far include:
1. The Sanchem products appear to offer some corrosion protection, but generally not equivalent to Alodine.
2. No comparison of Sanchem?s products to other systems (bare Alclad, epoxy primers, etc.) is available so it?s hard to compare to other systems.
3. The Sanchem products do require the Sealer to provide corrosion protection, whereas the Alodine performed well without any additional protection/coating.
4. Any additional primers/sealers/paints applied over the Sealer may not adhere well.
So where does this leave me? Thoughts/concerns include:
1. Due to the resulting clear color of the sealed surfaces, it will likely be difficult to see any areas where the protection has been damaged during assembly/riveting.
2. Sealer is clearly a must to achieve any corrosion protection, but aren?t some internal components painted with the exterior (e.g. rear of HS/VS spars, outside ribs, etc)? Adhesion problems?
3. When using the scotchbrite pads when cleaning with the Part C chemical is the diminished corrosion-proofing from the Alclad offset by the protection from the Sanchem system?
4. Applying the A/B/C pretreatments took a fair amount of time, and I didn?t do the skins and haven?t applied the sealer to anything yet.
5. Should I switch to an epoxy primer which I believe will be faster, simpler, and more reliable?
6. Should I stop worrying incessantly about these details and just get it done?
Anyways, I just thought I?d share what I?ve learned so far. If anyone has any other results with the Sanchem chemicals please post them.
Thanks,
Mike Behnke
RV-9A Empennage
