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Goop / caulk recommendations



 
 
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  #11  
Old March 15th 18, 11:51 PM posted to rec.aviation.soaring
jfitch
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Posts: 1,134
Default Goop / caulk recommendations

On Thursday, March 15, 2018 at 2:05:38 PM UTC-7, wrote:
On Wednesday, March 14, 2018 at 1:22:11 PM UTC-4, Jonathan St. Cloud wrote:
My trailer arrived with two soft solar chargers attached to the roof top via a sort of caulk/goop. Two years later the trailer is leaking under the solar panels. Looking for a recommendation for a goop or caulk that is white or clear, and can withstand the sun and heat of the Western USA flying spots?


Sikaflex is usually the "gold standard" in the RV industry. Any exterior penetration gets sealed with Sikaflex. Excellent caulk.


Both the Sikaflex 2xx and 3M x200 series are polyurethanes and they have similar and equivalent product lines. Both big in the marine and RV business. The 3M is perhaps a little more available in the US, but both are widely distributed. In 3M, 5200 is the strongest bond, 4200 is weaker (easier to remove later). Both come in a slow cure (like 72 hours) and a quick cure version (24 hours). 3M also has 4000 UV which is not a polyurethane, but rather a polyether. The bond is something like 4200 but it is more UV resistant. All of these products are very messy to work with, I recommend tightly masking the area around the part or fitting, immediately removing all of the excess making sure you have plenty of paper towels and a receptacle to put them in (or you and your trailer will be wearing a lot of it). Then immediately peel the masking and leave it alone until cured. A thick bond line will allow more differential movement between the pieces before failure, the most common cause of sealant failure. They are aggressive moisture curing adhesives, meaning that once the seal is broken they will eventually harden in the tube, so don't buy a lot more than you can use.

On a well prepared surface, the bond strength of 5200 or the equivalent Sika will be sufficient to hold anything in place once it has cured without fasteners (around 700 psi claimed). This is legend in the boating industry - 10,000 lead keels sealed with 5200 will not come off even hanging with the bolts removed. There are now some chemical de-bonding agents available, but they work slowly and tediously.

Experience from extensive use of all of these on boats over many decades.
  #12  
Old March 16th 18, 04:59 AM posted to rec.aviation.soaring
LongJourney
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Posts: 33
Default Goop / caulk recommendations

On Thursday, March 15, 2018 at 5:51:24 PM UTC-5, jfitch wrote:
On Thursday, March 15, 2018 at 2:05:38 PM UTC-7, wrote:
On Wednesday, March 14, 2018 at 1:22:11 PM UTC-4, Jonathan St. Cloud wrote:
My trailer arrived with two soft solar chargers attached to the roof top via a sort of caulk/goop. Two years later the trailer is leaking under the solar panels. Looking for a recommendation for a goop or caulk that is white or clear, and can withstand the sun and heat of the Western USA flying spots?


Sikaflex is usually the "gold standard" in the RV industry. Any exterior penetration gets sealed with Sikaflex. Excellent caulk.


Both the Sikaflex 2xx and 3M x200 series are polyurethanes and they have similar and equivalent product lines. Both big in the marine and RV business. The 3M is perhaps a little more available in the US, but both are widely distributed. In 3M, 5200 is the strongest bond, 4200 is weaker (easier to remove later). Both come in a slow cure (like 72 hours) and a quick cure version (24 hours). 3M also has 4000 UV which is not a polyurethane, but rather a polyether. The bond is something like 4200 but it is more UV resistant.. All of these products are very messy to work with, I recommend tightly masking the area around the part or fitting, immediately removing all of the excess making sure you have plenty of paper towels and a receptacle to put them in (or you and your trailer will be wearing a lot of it). Then immediately peel the masking and leave it alone until cured. A thick bond line will allow more differential movement between the pieces before failure, the most common cause of sealant failure. They are aggressive moisture curing adhesives, meaning that once the seal is broken they will eventually harden in the tube, so don't buy a lot more than you can use.

On a well prepared surface, the bond strength of 5200 or the equivalent Sika will be sufficient to hold anything in place once it has cured without fasteners (around 700 psi claimed). This is legend in the boating industry - 10,000 lead keels sealed with 5200 will not come off even hanging with the bolts removed. There are now some chemical de-bonding agents available, but they work slowly and tediously.

Experience from extensive use of all of these on boats over many decades.


This is very propitious information for me! I have a canopy that had the plexiglass attached only by something like Sikaflex. The glass had checked away in many areas. I removed the glass, cleaned the old adhesive off of the metal frame, and then reattached the glass with screws. I got a copy of the original drawings for the SHK from Shempp-Hirth (I'm restoring a Standard Austria S) which shows the canopy attached with countersunk screws. The drawing states that the gaps are filled in with some type of filler, very vague. But, the frame and the plexiglass do not come close to meeting at the very front. There is a gap of over an inch between the metal frame and the bend of the 'glass, which brings me to my problem--what do I use to fill in both the large gap at the front of the assembly, and in the fillets, top and bottom, between the frame and the glass running lengthwise? I think Sikaflex is what I need, but maybe the 3M 4000 product would be a better choice? Again, I have large gaps to fill in, plus the fillets between the glass and the metal tubing. I want a long-lasting, lightweight material that can be molded to provide a good seal with my fuselage. I also want someone to make all of these hard decisions for me! ;-)

Thanks,

Jeff
  #13  
Old March 16th 18, 05:34 AM posted to rec.aviation.soaring
sisu1a
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Posts: 569
Default Goop / caulk recommendations

Sikaflex 295 UV is literally made primarily for bonding/sealing plastic windows into frames and structures. It's also UV resistant as well as paintable.
  #14  
Old March 16th 18, 07:13 AM posted to rec.aviation.soaring
jfitch
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Posts: 1,134
Default Goop / caulk recommendations

On Thursday, March 15, 2018 at 8:59:10 PM UTC-7, LongJourney wrote:
On Thursday, March 15, 2018 at 5:51:24 PM UTC-5, jfitch wrote:
On Thursday, March 15, 2018 at 2:05:38 PM UTC-7, wrote:
On Wednesday, March 14, 2018 at 1:22:11 PM UTC-4, Jonathan St. Cloud wrote:
My trailer arrived with two soft solar chargers attached to the roof top via a sort of caulk/goop. Two years later the trailer is leaking under the solar panels. Looking for a recommendation for a goop or caulk that is white or clear, and can withstand the sun and heat of the Western USA flying spots?

Sikaflex is usually the "gold standard" in the RV industry. Any exterior penetration gets sealed with Sikaflex. Excellent caulk.


Both the Sikaflex 2xx and 3M x200 series are polyurethanes and they have similar and equivalent product lines. Both big in the marine and RV business. The 3M is perhaps a little more available in the US, but both are widely distributed. In 3M, 5200 is the strongest bond, 4200 is weaker (easier to remove later). Both come in a slow cure (like 72 hours) and a quick cure version (24 hours). 3M also has 4000 UV which is not a polyurethane, but rather a polyether. The bond is something like 4200 but it is more UV resistant. All of these products are very messy to work with, I recommend tightly masking the area around the part or fitting, immediately removing all of the excess making sure you have plenty of paper towels and a receptacle to put them in (or you and your trailer will be wearing a lot of it). Then immediately peel the masking and leave it alone until cured. A thick bond line will allow more differential movement between the pieces before failure, the most common cause of sealant failure. They are aggressive moisture curing adhesives, meaning that once the seal is broken they will eventually harden in the tube, so don't buy a lot more than you can use.

On a well prepared surface, the bond strength of 5200 or the equivalent Sika will be sufficient to hold anything in place once it has cured without fasteners (around 700 psi claimed). This is legend in the boating industry - 10,000 lead keels sealed with 5200 will not come off even hanging with the bolts removed. There are now some chemical de-bonding agents available, but they work slowly and tediously.

Experience from extensive use of all of these on boats over many decades.


This is very propitious information for me! I have a canopy that had the plexiglass attached only by something like Sikaflex. The glass had checked away in many areas. I removed the glass, cleaned the old adhesive off of the metal frame, and then reattached the glass with screws. I got a copy of the original drawings for the SHK from Shempp-Hirth (I'm restoring a Standard Austria S) which shows the canopy attached with countersunk screws. The drawing states that the gaps are filled in with some type of filler, very vague. But, the frame and the plexiglass do not come close to meeting at the very front. There is a gap of over an inch between the metal frame and the bend of the 'glass, which brings me to my problem--what do I use to fill in both the large gap at the front of the assembly, and in the fillets, top and bottom, between the frame and the glass running lengthwise? I think Sikaflex is what I need, but maybe the 3M 4000 product would be a better choice? Again, I have large gaps to fill in, plus the fillets between the glass and the metal tubing. I want a long-lasting, lightweight material that can be molded to provide a good seal with my fuselage. I also want someone to make all of these hard decisions for me! ;-)

Thanks,

Jeff


Sikaflex 295 is made for this purpose (sealing plexi), but I've had poor luck with it. They highly recommend their primer which is both very expensive and has a very short shelf life. Even using all that and following the instructions to the letter, boat hatches that I had attempted to reseal (plexi into an aluminum frame) failed within a year or two. Many in the yacht industry use Dow Corning 795 for this, and several have recommended it after failures with Sikaflex 295. The Dow product is a silicone base, sold for glazing commercial buildings. Neither of these has very strong adhesive claims.. Some polyurethanes can attack plexi (PMMA plastics) so you want to be careful what you use. None of the products discussed would be good for filling 1" gaps. The only adhesive I have every seen that claimed to fill 1" gaps is Plexus, a methacrylate. Plexus is some amazing stuff, but is quite unforgiving in application, I would be reluctant to use it there. You probably need to mold or fit something to fill most of the gaps before the sealing starts. If it where me, I'd try Dow 795 and secure it with screws, after making something to fill the gaps to 3mm or less. With any of these, I'd maintain a glue line of at least 1 - 2mm with spacers (monofilament fishing line can be used across the joint) to allow movement, snug the fasteners just enough to achieve that, wait for the sealant to cure, then tighten the fasteners very slightly for compression.
  #15  
Old March 16th 18, 11:18 PM posted to rec.aviation.soaring
Jonathan St. Cloud
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Posts: 1,463
Default Goop / caulk recommendations

Thanks for all the help guys!

On Thursday, March 15, 2018 at 3:51:24 PM UTC-7, jfitch wrote:
On Thursday, March 15, 2018 at 2:05:38 PM UTC-7, wrote:
On Wednesday, March 14, 2018 at 1:22:11 PM UTC-4, Jonathan St. Cloud wrote:
My trailer arrived with two soft solar chargers attached to the roof top via a sort of caulk/goop. Two years later the trailer is leaking under the solar panels. Looking for a recommendation for a goop or caulk that is white or clear, and can withstand the sun and heat of the Western USA flying spots?


Sikaflex is usually the "gold standard" in the RV industry. Any exterior penetration gets sealed with Sikaflex. Excellent caulk.


Both the Sikaflex 2xx and 3M x200 series are polyurethanes and they have similar and equivalent product lines. Both big in the marine and RV business. The 3M is perhaps a little more available in the US, but both are widely distributed. In 3M, 5200 is the strongest bond, 4200 is weaker (easier to remove later). Both come in a slow cure (like 72 hours) and a quick cure version (24 hours). 3M also has 4000 UV which is not a polyurethane, but rather a polyether. The bond is something like 4200 but it is more UV resistant.. All of these products are very messy to work with, I recommend tightly masking the area around the part or fitting, immediately removing all of the excess making sure you have plenty of paper towels and a receptacle to put them in (or you and your trailer will be wearing a lot of it). Then immediately peel the masking and leave it alone until cured. A thick bond line will allow more differential movement between the pieces before failure, the most common cause of sealant failure. They are aggressive moisture curing adhesives, meaning that once the seal is broken they will eventually harden in the tube, so don't buy a lot more than you can use.

On a well prepared surface, the bond strength of 5200 or the equivalent Sika will be sufficient to hold anything in place once it has cured without fasteners (around 700 psi claimed). This is legend in the boating industry - 10,000 lead keels sealed with 5200 will not come off even hanging with the bolts removed. There are now some chemical de-bonding agents available, but they work slowly and tediously.

Experience from extensive use of all of these on boats over many decades.


 




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