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Skin adhesive narrowed down

PostPosted: Fri Sep 22, 2017 11:22 am
by LMarsh
Just wondering if anyone had some thoughts on adhesives for the aluminum skin. I know some float them but in the past I've always glued them down with good results. I've never experienced oil canning so I'll continue using an adhesive. That being said I'm not completely sure whether all or any of the adhesives don't eventually let go after many expansion and contractions of sub zero winters and 90 degree summers. Nor am I excited about spending another $100 or so on overkill adhesives. I've read many posts on this site with some recommendations and also many mentioning Sika (though the exact type is often left unsaid). I'm technically gluing two non porous surfaces since I sealed my entire plywood shell with epoxy. I'll rough up both surfaces prior to gluing. I don't want to use contact cement because of re-positioning issues. I've got my personal choices narrowed down for this build as follows:

Sikabond Construction Adhesive (or Sika Pro Select) - Cheap, especially in 29 oz tubes, available at local big box stores, stays flexible/elastomeric, polyurethane based, sticks well to almost everything. Upon reading the data sheets it seems very similar or the same as the Sikaflex 11FC. In the past I think what I used was DAP polyurethane in various colors but it doesn't seem available in my area anymore. I bought a tube of Sikabond and played with it on some materials with pretty good results.

Sikaflex 252 - Two, almost three times more expensive & haven't found it locally (might be a problem if I run out and need more), upon reading the data sheet it has good characteristics and I've seen it recommended on this site, as well as Sika 221.

Lord Fusor 800DTM/803DTM - Silane Terminated Polymer (STP) based. Most expensive, potentially triple if purchased online or even more locally, than Sikabond. It was recommended I contact Lord by SAF metals and then the Lord rep recommended this to me after discussing the teardrop project. I did tell them cost was a consideration but also quality products. Appears to be a professional level automotive seam sealer with all the right properties. The rep thought it was the best product for the expansion/contraction differences of the wood and aluminum, and will stick to the epoxy.

Re: Skin adhesive narrowed down

PostPosted: Fri Sep 22, 2017 2:33 pm
by dancam
Trailers are now being built by manufacturers using adhesives to bond the skins to the frames. Lots of panel adhesives used in vehicles instead of welding, same as planes.
This is just the first link i found when i did a google search. 3m has some great panel bonding adhesives for vehicles, theres some good info here on their products for trailers. They sound better than seam sealer...

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Re: Skin adhesive narrowed down

PostPosted: Fri Sep 22, 2017 9:54 pm
by LMarsh
Yeah I've read a few articles and watched some videos on that kind of thing. The actual adhesives can be crazy expensive though. I briefly looked into it but I didn't think it was a viable option. I only have a single small seam anyway. I'm using 5'x12' sheets and the only seam is on the roof towards the back. Besides that mechanical fasteners will be holding down all the edges with trim, the roof vent, door, and two windows. I only have two goals for using adhesives. First to hold the sheets in place so I can easily install the trim, door, windows, etc at my leisure, and then to help avoid oil canning or movement of the sheets for cosmetic reasons. If that's even possible. On my previous builds the trailers were pretty small and while this one is larger, they're still small trailers. I never saw much buckling or anything on my previous builds. I figure if the sheets are going to move due to expansion they either will or won't regardless of what I do. I don't know, I'm an amateur and not an engineer. Every build is different. I think I'm going to plan on using a combination of the above adhesives for cost savings. I have a friend at an auto body supply shop and I'll grab a couple tubes of the Fusor. He told me that stuff would never let go. I'll try it in the larger spaces of the roof and driver's side, and then do the perimeter and around the openings in the cheaper SikaBond since it'll be screwed down there too anyway. I figure about $60 should do it.