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Improper Sika Primer Being Used in RV's?

Noah

Noah

Well Known Member
What am I missing... Both Sika's website, and Jamestown Distributor's website, which sells the Sika line, require the use of a primer on aluminum & steel that, as far as I can tell, nobody uses. :confused: I don't know about you, but I would think that following the manufacturer's instructions TO THE LETTER would be highly advisable on your canopy where you really only get one shot to get it right.

The way I am reading this, Sika 209N primer is required on the plexi side, and Sika Activator and Sika 206 G&P are required on the aluminum or steel side of the bond.

Yet Mickey Coggins' site and the Matronics site regarding canopy bonding- widely considered the authority and central knowledge base for Sika canopy bonding, does not mention Sika 206 G&P, unless I missed it somehow.
http://www.rv8.ch/article.php?story=20050617213651709
http://wiki.matronics.com/wiki/index.php/Gluing_Your_Canopy

Additionally, a search of Sika 206 G&P doesn't turn anything up on VAF either.

Check my math. According to:
http://www.sikaindustry.com/primer_chart_4-21-06.pdf
our application is an "application involving large components where there is joint movement. examples: "...WINDSHIELDS, side windows". The joint movement arises from the difference in thermal expansion with temperature between the aluminum and the plexi. Thus our application is a LEVEL II sealing / bonding application, and requries scothhbrite, followed by SIKA ACTIVATOR, followed by SIKA 206 G&P on untreated aluminum and steel.

Similarly, videos on Jamestown Distributors website call for the 206 G&P:
http://www.jamestowndistributors.com/userportal/show_product.do?pid=3508

Yes, this will add to the cost of a Sika installation because these primers and cleaners aren't cheap. However, this is no place to cut corners. Why then, does it seem that nobody has used the Activator and 206 G&P primer on aluminum & steel as required by the manufacturer for our application? :confused::confused:
 
Primer wars!!!

Noah,

I used Sika on my canopy, and followed the process used by two other builders - one RV-8 and another RV-7. Both sites were very specific about the necessity of using the primer.

Sika's data sheet is specific about the primer - if you don't use it, don't expect the SikaFlex to devolop full adhesion to the material that you're bonding. This means that the primer has to be applied to both the canopy AND the frame! There is also a timeframe from when the primer is applied to when the SikaFlex has to be applied. Don't think that you can scuff the primer to enhance adhesion if the time has passed. You must apply a new layer of primer prior to using the SikaFlex.

So the short answer is "You must use the Sika Primer!"
 
DakotaHawk said:
I used Sika on my canopy, and followed the process used by two other builders... So the short answer is "You must use the Sika Primer!"
Click to expand...

I think you may have entirely missed my point.

Nowhere in my post did I suggest that you should not use Sika primer. What I AM suggesting is that we should be using TWO DIFFERENT primers (one for the metal and one for the plexi), and that Primer 209N is THE WRONG PRIMER to use on the aluminum / steel side of the bond. It is the RIGHT primer to use on the acryllic. According to Sika, Primer 206 G&P is the RIGHT primer for the metal side of the bond. What I AM suggesting is that using the WRONG primer would likely result in LESS THAN OPTIMAL ADHESION on the metal side of the bond.

As everybody knows, proper surface preparation and use of appropriate primers is EVERYTHING in bonding. So has this been a case of the blind leading the blind? Has nobody come across this before? As I said, there seems to be NO MENTION of Sika 206 G&P primer on ANY RV builder website. How can this be? Is it a brand new product? Has Sika recently changed their recommendation regarding primers? RV builders tend to be careful and methodical, so as I said, I must be missing something. I just don't get it. :confused:
 
I missed your point!

Yep! Now I see what you were saying. I'll have to look at what I used when I get out to the shop this afternoon. I'm pretty sure that I only used one type of primer. I still have all of the left overs, so I'll see what I can find. Maybe I did it wrong as well.
 
Do you think it might have to do with the fact that most are applying the primer over scuffed powder coat and not bare aluminum or steel. I'm curious as I am getting ready to order my Sikaflex next week.
 
I think Jim may have hit the nail on the head. Check out what the demonstrator said during the last Jamestown video in Noah's initial message.

At 1:30 into the video, he states that "209N is critical for polycarbonate bonding.... and for bonding to paint surfaces like powder coat".

As long as you're using a powder coat frame, it looks like 209N is all you need for primer.
 
Gunter Malich said:
As long as you're using a powder coat frame, it looks like 209N is all you need for primer.
Click to expand...

That MIGHT be true on a slider, but you're bonding to bare aluminum EVERYWHERE on a tip-up. For those building sliders, do you REALLY trust the adhesion of the powder coat? If it were me, I'd want to take it down to bare metal and use the correct stuff, but hey, that's just me.
 
Maybe the best thing to do is paint the surface with a urethane if it is not powder coated. Jamestown says of the 209D (replaces 209N), "It is used to prime painted surfaces and plastic substrates prior to bonding with Sikaflex products. 1/2 Pint."

Also see www.sikaindustry.com/primer_chart_4-21-06.pdf note number 10 for the type of paint.

Ken
 
I think Noah is correct, the bare metal primer is required if bonding to a tip up frame. I'm also having my slider frame sand blasted back to bare metal and re-powder coated with the correct primer under the powder coat. Every time I chip any of Van's powder coat there is bare metal underneath that has not been prepared very well - I'm also having the engine mount done.

Pete
 
Ever try to remove powder coat?

Anyone that has tried to remove powder coat from steel parts will attest that you are better off bonding to the powder coat with the 209 primer than removing the powder coat and using the 206.

The powder coat is incredibly tough, durable, and BONDED. the only expeditious way to get it off is to burn it off with a propane torch.

If you remove it and bond to bare steel, you are opening the door for rust anywhere that is not completely protected/sealed. Even the possibility of a light film of rust forming between the removal and sanding and the application of primer or whatever.
 
scsmith said:
Anyone that has tried to remove powder coat from steel parts will attest that you are better off bonding to the powder coat with the 209 primer than removing the powder coat and using the 206.

The powder coat is incredibly tough, durable, and BONDED. the only expeditious way to get it off is to burn it off with a propane torch.

If you remove it and bond to bare steel, you are opening the door for rust anywhere that is not completely protected/sealed. Even the possibility of a light film of rust forming between the removal and sanding and the application of primer or whatever.
Click to expand...

I bent one of the little tabs on my rudder pedals to get it aligned with the brake cylinder. A big chunk of powder coat came right off.
 
Jamestown website says

"This black primer(206) is used to prep Sika 296. "

Does that mean that Sika 295UV is wrong?
 
I'll call Sika today and ask them the difference in the two primers and see what they have to say. I'll post the results here later.
 
Lionclaw said:
I bent one of the little tabs on my rudder pedals to get it aligned with the brake cylinder. A big chunk of powder coat came right off.
Click to expand...

Andy's accurate observation should be telling information for anybody. The word "powdercoat" is nothing more than a soundbite describing a basic process. Because no true convention exists, qualitywise, application quality and standards are all over the place. For instance, the powdercoating applied to various components on my Ford truck is incredibly durable stuff yet the light gray "powdercoat" found on RV weldments can come off in chunks as in Andy's case, and any of it can be easily broken down, dissolved and removed with a rag or scotchbrite pad soaked with MEK. Don't take my word for it....try it on a test piece yourself. That fact should be carefully considered when bonding anything of critical importance directly to "powdercoated" surfaces on RV parts.
 
Thanks for posting this here. I considered using SikaFlex but went with the bolts down the frame sides and tank sealant across the front sans the aluminum tabs. My reason for doing it that way was that I couldn't figure out how I'd do a nice job of applying SikaFlex. I'd like to see a tip up done with Sika just to see it. I'm happy with the way my tip up came out and wouldn't change it.
 
gary Bricker

Come to Pecan Plantation fly in in May and you can see several. Going on 3years and no problems and one primer
 
Sika's Response

I spoke to Steve Padgett, a "Technical Coordinator" at Sika today, and asked him about the use of 209N primer on bare metal vs. 206 G&P. His response was that 209N would probably be OK, given discussions he has previously had with the R&D folks at Sika, but it had not been validated. 206 G&P has been tested and validated.

I also asked what the difference was between primer 209N and 209D, which is newer and replaces 209N. The 209D is a little easier flowing and will prevent "drag marks" if the primer is applied with a brush.

I ordered a can of 206 G&P today from Jamestown Distributors, $53.38.
 
AX-O said:
So did they tell you to use Sika 296 or 295?
Click to expand...

Sika 296 is used for mineral, or inorganic, glass - and is not appropriate for acrylic. Sika 295UV is appropriate for acrylic or polycarbonate plastic windows.
 
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scsmith said:
Anyone that has tried to remove powder coat from steel parts will attest that you are better off bonding to the powder coat with the 209 primer than removing the powder coat and using the 206.

The powder coat is incredibly tough, durable, and BONDED. the only expeditious way to get it off is to burn it off with a propane torch.
Click to expand...


My experience was that stripping the powder coat off the roll bar and slider frame was pretty easy and that it wasn't bonded particularly well. I decided to strip and paint after seeing that the powder coat on my parts wasn't very durable.

Perhaps this is a QC thing with varying quality from piece to piece?
 
I don't recall a single incedence report of any de-bonding/delaminating of ANY canopy that was attached using Sika, regardless of whether the powdercoat was removed or what primer was used. We are indeed collecting imperical data here, even if it's anecdotal! :D

If something has come apart it would be really good to know. Maybe I missed it.
 
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ive found the sika also bonds aluminium to fibreglass really well, I've also used it for bonding the wing tip hinges along with rivets. its rock solid.
 
I ground the powder coat off, used what was then 226 cleaner for the canopy, now replaced by 206 Activator which I used on the windscreen (lot of time between those two activities), 209D primer on both plexi and tube, and 295UV glue. Although I'm not flying yet the bonding seems extremely strong. I personally wouldn't do it any differently. The people at Sika are notoriously reluctant to give too much direction since their products are not really designed for aviation use.
 
OK I'm in

Going to give gluing a shot, as the canopy(bought RV8 kit) I got already had the pilot holes, but not enlarged.. would like to do the Paul Dye method with surgical tubing inserts , but.. some are close to the edge of the plexi. and this looks like a good way to go..

also good prices from
https://www.merrittsupply.com

should have leftover supplies, ??? so anybody in N. Georgia at the same build point, let me know!

ALL advice welcomed!
/Andy
 
We Sika'd our -7 tip-up canopy about 2 years ago and are now flying. That stuff is solid as can be, yet elastic enough to give a little when necessary.
 
slight hijack.....

so how did it come to pass that the RV world uses Sika, if anything, and the entire Glasair/Glastar world uses nothing but Silpruf?
http://www.siliconeforbuilding.com/document-weatherseal
http://www.pksupplies.com/ge-silpruf-scs2000-precast-white-silicone-sealant.html
perhaps there's some slight differences in the structure, the fibreglas lap joints are more suited to Silpruf? It seem very common in the marine and auto world as well for windshield installation etc.

anyone used both?
 
flyboy1963 said:
so how did it come to pass that the RV world uses Sika, if anything, and the entire Glasair/Glastar world uses nothing but Silpruf?
http://www.siliconeforbuilding.com/document-weatherseal
http://www.pksupplies.com/ge-silpruf-scs2000-precast-white-silicone-sealant.html
perhaps there's some slight differences in the structure, the fibreglas lap joints are more suited to Silpruf? It seem very common in the marine and auto world as well for windshield installation etc.

anyone used both?
Click to expand...


good question..??
Adhesion ? SCS2000 features primerless adhesion to most nonporous construction materials, eliminating the risks associated with improper primer application on those materials and reducing costs associated with primer and subsequent labor. SCS2000 can be used with many substrates and finishes, including: glass, polycarbonate, vinyl, plastics, coated and anodized aluminum, concrete, brick, and wood.
 
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