I need to glue some aluminum box beams to the fiberglass gel coat on the roof of the coach, permanently if there is such a thing.
I tried 5200 and had a catastrophic failure. The 5200 did fine attaching to the gel-coat/fiberglass but had very little bonding to the aluminum box beam. This became apparent when we had a week of 100 degree weather and there was a shear load applied to the box beam ( about 18' and 200# of solar panels tilted to about 60 degrees so I could work under them, took a dive from the roof to the ground. They were in this position for about one week. I guess there was about 50#-70# of actual load. Those commercial panels are tough, NO damage to the panel bank but sheared off one of the storage compartment T handles on the way down)
I learned a lesson and got off easy because the coach was in my back yard when the failure occurred, had I been driving I shutter to think about what could have been. I guess that if the panels were flat I would never had seen how little adhesion there actually was to the aluminum and a separation MAY NOT have ever happened. Hard to calculate how much wind lift could be generated under the panels at interstate speed with the required 4" of separation from the roof to the bottom of the solar panel.
I will, from now on, NEVER attach anything of substance to the roof with out gluing AND bolting it down. Pierce has posted, and I have read, many times, his wisdom of bolting things down and not relying solely on the "wonder" adhesives that are out there.
When I glue something at home I can only assume that its secure, I don't have a testing lab at home to confirm.
I have thought about a Silicone adhesive, is there a better choice?
3M VHB tape. If that don't hold it nothing will. A lot folks use it to hold the solar panel mounts on.
This is used extensively for auto body and boat repair. Expensive but effective where surface is uneven or a gap to fill.
3M Structural Adhesive, 08101 (https://www.amazon.com/dp/B000KZUTCY/ref=cm_sw_r_sms_apa_i_Si8oFb05PF0S0)
Lon, Sorry your 5200 didn't work, maybe not what it was designed for. I would use 3M VHB tape. All of my solar panels are mounted using it (as are many) and after six years they are rock solid. I moved one panel and the only way to get to mounts off the roof was to cut them off and then a lot of time to get the remaining VHB off of the roof and mount.
I used this tape. Specs say 91 psi in tension. So for a 1.5" tape x 12" that is more than 1600 pounds per foot.
Amazon.com: 3M VHB Heavy Duty Mounting Tape 5952, 1.5" width x 5yd length (1... (https://amazon.com/gp/product/B00HLY7BBO/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)
Along with careful surface prep and this primer/adhesion promoter Amazon.com: 3M 111 Clear Tape Primer - Liquid Bottle - For Use With 3M VHB... (https://amazon.com/gp/product/B00745Z8BK/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)
It should work fine. Caulk the aluminum to fiberglass edges to protect the VHB tape with 3M 4000 UV caulk.
Probably a good idea to make your aluminum tube sections shorter and leave gaps for expansion and contraction.
With expansion and contraction of aluminum especially on the roof with temperature extremes good luck with any type adhesive.
There are probably hundreds of different silicon glues. RTV "room temperature vulcanizing" they have hi adhesion hi temperature. The key for me is using the RTV primers. Makes it virtually unremovable. Most people have never used the primer. My personal favorite for bonding is 3m scotch weld structural adhesive. Seems to work on every thing including polystyrene Styrofoam. I've built boxes with it for years. I get the time expired scotch weld from work. It works very well with aluminum if prepped well. Saves them from having to dispose as hazardous waste. Down side is you can't remove without destroying something or both.
Scott
AM Solar uses the 3M VHB tape on their installations. If the tape was failing I am sure we would have heard about it on the forum. That is what is holding my panels down.
I second Rogers advice. I used VHB tape then used 3m caulk around edges and then just for belt and suspenders add two screws to each foot. I think the roof would go flying off before the panels come off.
I purchased my mounts through AM Solar also:
https://youtu.be/mXiNLCWPPkA
Did the 5200 separate from the gelcoat or did it pull off the gelcoat when it separated?
My solar panels are mounted with 5200 and I added a screw through each foot.
The 5200 stuck to the gelcoat but hardly at all to the aluminum. To remove the 5200 from the gelcoat I heated it with a torch and then scraped it off. It released very easy with the heat application.
I had sanded the gelcoat and the aluminum with a belt sander and 60grit belt to roughen the surfaces, and cleaned both with alcohol prior to gluing.
Lon
Should not have use alcohol. See below preparation instruction for 5200.
Directions for Use Surface Preparation:
There are waxes, coatings, sealants, grease, oil and other contaminants used in the
marine industry, making it very important to clean all surfaces to be bonded before
applying 3M™ Marine Adhesive/Sealant Fast Cure 5200. Recommended procedures
include cleaning with 3M™ General Purpose Adhesive Cleaner 08984.*
Application of Adhesive Sealant: Abrading the surfaces with a 180 grit to 220 grit abrasive will enhance the bond strength. Cut tip to desired bead size, puncture seal in nozzle and remove the seal at bottom end of cartridge. Place cartridge in a caulk gun. Apply 3M Marine Adhesive/Sealant Fast Cure 5200 to the seam or part to be bonded. Position parts. Tool material to desired appearance. Remove excess with 3M General Purpose Adhesive Cleaner 08984.* Sealant should be used within 24 hours after inner seal is punctured, as product will start to cure in the cartridge and nozzle. Cure: Cure Relative Humidity Temperature Time Cure Depth
Open Time 50% 70°F (21°C) 1 hour N/A Open Time 90% 90°F (32°C) 15 minutes N/A Full Cure 50% 70°F (21°C) 24 hours 1/8 inch 0.3175 cm) Cleanup: For cleaning 3M Marine Adhesive/Sealant Fast Cure 5200 before it is cured, use a dry cloth to remove the majority of sealant, followed by a cloth damp with 3M General Purpose Adhesive Cleaner 08984,* toluene or acetone. Cured 3M marine Adhesive/ Sealant Fast Cure 5200 can be removed mechanically with a knife, razor blade or sanding. *Note: When using solvents, extinguish all ignition sources, including pilot lights, and follow the manufacturer's precautions and directions for use.
Limitations: - Alcohol should not be used in preparation for bonding as it will stop the curing process.
- Heat resistance - Maximum 190°F (88°C). Due to the decreased value in bond strength at elevated temperatures, we do not recommend use of this product above 190°F (88°C). - Do not apply at temperatures below 40°F (4°C) or on frost covered surfaces.
- 3M Marine Adhesive/Sealant Fast Cure 5200 is not recommended for use as a teak deck seam sealer. Extended exposure to chemicals (teak cleaners, oxalic acid, gasoline, strong solvents and other harsh chemicals) may cause permanent softening of the sealant.
Thanks for the research that I should have done before application. I now read that it is NOT recommended to bond aluminum.
My BIG mistake was NOT doing enough research on my own, but relaying on internet advice and posts. I read so many posts and reviews on line about 5200 and its famed "once you glue something with it, DON'T ever expect to remove it" comments that I became a believer.
Because of my ignorance and the admittance that I'm NOT a structural or chemical engineer and NOT a professional installer using these products on a daily basis, I have no right to assume I have enough knowledge to "wing it" in picking these types of products.
This why I concluded that any type of adhesive I use in the future will be backed up with a mechanical fastener.
Lon
Don't beat yourself up. There are plenty of rude people in the world to do that for you. LOL. Research is good, it will take you down false paths and you will still learn what not to do. There are a lot of experts on this forum, me not included, that have been through what you are going through. Use advice to do research and then formulate maintenance plan in a step by step fashion. It is to ensure you don't forget something or "didn't see that coming" event. Good luck
Years ago I used Marine Tex to bond an aluminum mount to a FG cockpit, an aluminum bracket for an auto pilot. It was subjected to some unbelievable strong loads from the rudder on a 35 ft race boat. I did have it attached also by some nuts and bolts. Years later it had not even a hairline crack. You might check with the mfg for its bonding strength. The description says it bonds to metal and FG.
I've also bonded 6 solar panels, 1800 watts, to my roof using AM Solar brackets and some homemade aluminum brackes using nothing but 3M 4950 tape.
3M 4950/WI15 Scotch 4950 VHB Tape: 1" x 15 ft, White Amazon.com: 3M 4950/WI15 Scotch 4950 VHB Tape: 1" x 15 ft, White: Industrial... (https://www.amazon.com/dp/B00CC14L96/ref=cm_sw_r_em_apa_i_r1ipFbEDFBGKC)
Marine Tex RM303K 3 Lb.Grey Marine Tex Kit Made by Marine Tex Amazon.com : Marine Tex RM303K 3 Lb.Grey Marine Tex Kit Made by Marine Tex :... (https://www.amazon.com/dp/B003E1ZBII/ref=cm_sw_r_em_apa_i_SOipFbPVK57B1)
You can bond aluminum with epoxy. It's all about sanding the aluminum then immediately applying the epoxy before oxidization starts.
Call these people, there is nothing they don't know about epoxy.
West Systems
WEST SYSTEM Epoxy - Marine Grade Resins & Hardeners (https://www.westsystem.com)
866-937-8797
Keith