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Re: Softer, longer lasting Rain Gutter Seam Sealer?
rebar #724006 May 26th 2017 2:26 am
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I read the same thing about acetone mieral spirits and laquer thinner. They sell some sort of alpha and Omage degreaser for ultimate bonding to metal, i forget what it is called but I did not bother acquiring it.

Ospho remnants, well in my experience it only has a white powder if the surface had no contaminants on it, and this can be brushed off with a green scrubbie pad. If it is still green and gummy then wipe up the residue lightly with more ospho on a paper towel until clean and hit the steel with a hair dryer until it is obviously dry, and it will be obvious.

I've gotten short of time and used denatured alcohol too to wipe the steel of Ospho pre epoxy, but I have also scrubbed the steel with wet/dry 60 grit folded over a piece of sponge for maximum mechanical tooth.

Be very precise when mixing the Epoxy. the bond strength and cure strength are depependent on a precise resing to hardener ratio, it is not like polyester resin, usually called fiberglass resin, to which one adds X amount of catalyst.

I hated west systems for its 5 to 1 ratio which made it all too easy to mess up.

I now use a small digital scale and measure my batches of epoxy to the 0.01 th of a gram.

When mixing the epoxy, make sure the mixing stick can get into the corners of the mixing cup. Mix on a level surface under a lot of light and mix it until you can see no swirlies. Wipe all 5 sides of the mixing stick more than once and remix that into the mixing cup. Do not spill any epoxy down the sides of the cup when mixing, If you do this can throw off the ratio of hardneer to resin, especially if in the early stages of mixing.

Keep the hardener off your skin. The sanding dust is toxic for about 3 days, then inert.

If one mixes epoxy incorrectly it might still harden, but not cure to its full strength or hardness or elasticity or bond as strong as it otherwise would. If one does nto fully mix the resin and hardener there will be parts which harden and others which stay soft.

i canlt stress enough how important it is to mix in the proper ratio, and mix it thoroughly I find a strong hedlamp aimed ito the mixing cup reveales 'swirlies' I could not see with naked eye, and those swirlies indicete more mixing is needed. I generally spend no less than 3 minutes mixing the epoxy, scraping the mixing stick on the side of the cup, spilling none on the outside, then scraping the side of the cup and mixing it again, over and over.

If it does go wrong, fixing the mistake is 2x as much work as you have already done, and toxic.

One method I came across since my last posting in this thread is the use of a clear plastic baggie on top of the
still wet and moldable epoxy. Much better than waxpaper. i would use various tools to push out any bubbles and shape the epoxy/ fiberglass to whatever shape I wanted. I've been using the large ziplock freezer baggies but some uncreased plastic would be better. The epoxy will not bond to the plastic, just let it fully cure and peel it off and one can reduce the level of sanding by a huge amount, or possibly eliminate it.

I have fixed rail dings on my surfboards using this method and not have had to sand at all once I remove the plastic. I was using a squeegee to push out all extra epoxy on top of the masking tape I confined the ding with, but, then razoring just inside the tape and removing tape leaving plastic in place while epoxy cures, but my last job I used no tape, just pushed the epoxy to the edge of the plastic and soaked it up with a napkin. It came out great and glossy and ready to go.

The roof gutter can fight, the plastic trick can really be useful on stubborn areas. Keep some around ready to go. DO not work in direct sun, and do not leave the properly mixed epoxy in the cup for very long as it will create its own heat and start gelling fast. Spread it thin in a tray to increase working time while applying it.

Keep moisture/humidity off the epoxy while it cures which might take 72 hours. If it gets wet then it might turn white and then this must be sanded off before painting, or layering more epoxy in another batch, but west system epoxy will require this anyway.

I can;t stress the proper ratios enough, you get about a 3% margin for error, and mix it in the cup wisely, and for about 2x as long as you think it requires to be fully mixed, then perhaps a bit more. From there the clock is ticking.

Re: Softer, longer lasting Rain Gutter Seam Sealer?
wrcsixeight #724011 May 26th 2017 7:36 am
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Again, thanks wrcsixeight.

Iv been mixing/measuring epoxy (MarinEpoxy from boat builders central) on my digital scale which is very consistent and weighs to the tenths of a gram.. Its great especially for small batch's and clean up is non existent with ziploc bowls and West Systems plastic stir sticks which fit the round corners of the bowls. The ratio is 100 parts resin for 43 parts hardener by weight. It is still 100 parts to 50 by volume but the hardener is heavier. So I multiply how much resin I just poured by 1.43 and add hardener to that amount. Great tip!

[Linked Image]

There's another thing other than metal prep I still don't feel comfortable with.. Filler recipes.

I'm using Milled glass fiber, silica and microballoons..
Iv read a good rule of thumb is about 1/2 tsp of Milled fiberglass per ounce of epoxy. And have read no more than 1/3 as much cabosil as filler, whether it is flock or microballoons.. so I will try 1/3 cabosil and 2/3 microballons... I guess..

But I'm winging it here and having to wait a few days to know if my testing batch was a success, and how to test and grade the success and how to further tweek the recipe is beyond me.. I need a filler recipe book.


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Re: Softer, longer lasting Rain Gutter Seam Sealer?
rebar #724018 May 26th 2017 1:12 pm
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I am not really so upto date on the fillers. My need for them is limited. I always had issues with cab o sil turning into a cottage cheese consistency and started avoiding its use

I use milled fibers and wood flour. The milled fibers go in the mixed epoxy first and is kindof difficult to get the lumps out. My fibers must be milled from volan cloth as there is a greenish tint.
The wood flour I use is just Western RedCedar sanding dust I collected from my belt sander, I add that second until it is just a bit thinner than I want, then spread it thin on a tray to extend working time, and hopefully it is the right thickness when I apply it or clamp it. The amount of wood flour depends on how thick I want it. i just add more and more until it is like runny peanut butter than slow down the amounts I add. It takes a lot more dust than I expect, usually.

My epoxies range from 100:45 to 100:43 by weight, and a even 2:1 volume ratio. I pour the resin in the cup, multiply that weight by 0.45, hit the tare button ,then pour the hardener to the 0.01 of a gram. My batches can be as small as 7.5Ml so I dig this level of precision that one cannot really achieve when pouring by volume.


Re: Softer, longer lasting Rain Gutter Seam Sealer?
rebar #724023 May 26th 2017 5:17 pm
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3M offers several different cleaners which are specific to cleaning surface contaminants due to old adhesives, prior to new adhesive or paint application. A particularly convenient one is their 3M General Purpose Adhesive Cleaner 15oz. Aerosol #08987, which is inexpensive and simple to use, as it comes as a conventional spray can,, and it addresses your one concern by being a less volatile material, so it deals handily with lifting embedded contaminants out of deep pores and surface texture after abrasives have been used. It is also available in quarts, as 3M 8984 General Purpose Adhesive Cleaner - #08984.

Another strong possibility might be 3M Prep Solvent-70, Gallon, #08983.

Last edited by Ram4ever; May 26th 2017 5:21 pm.

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Re: Softer, longer lasting Rain Gutter Seam Sealer?
Ram4ever #724032 May 27th 2017 7:36 am
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I would pick the 3M Prep Solvent-70 as its intended use is cleaning "prior to coating"

I keep reading "Wax and grease removers".. But I also keep reading many pro's say you should use two metal preps. The first a solvent based cleaner.. And the second a water based cleaner like the 3M Prep Solvent-70..

As far as fillers.. I have high hopes that the silica will make the epoxy thixotropic, or defy gravity. MGF is for strength and microballoons ease sanding.. But its the thixotropic properties of silica which I hope helps keep the epoxy from running down hill.

I wish I knew what fillers bondo glass and the like have mixed in them.

Last edited by rebar; May 27th 2017 7:41 am.

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Re: Softer, longer lasting Rain Gutter Seam Sealer?
rebar #724035 May 27th 2017 1:41 pm
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https://www.systemthree.com/blogs/epoxy-files/83508804-section-vii-c-modifying-epoxy-with-fillers

Mechanical tooth/ sanding scratches with sharp new sandpaper will help the bond greatly.

Before mixing anything into the epoxy to thicken it, paint some epoxy on the bare prepped metal. With bare wood this is very important as the wood can suck the epoxy out of the thickener and the bond line will fail, with metal one is just ensuring the valleys are filled with epoxy, not air.

It is important not to push contaminants into the valleys when sanding/ scratching for mechanical tooth.

I am not so impressed with the bond strength of regular bondo. it does sand nicely though. Sometimes epoxy can be a butch to sand. The plastic trick can greatly diminish the amount of sanding required.

Experiment before committing to any one method.

I am not always so fond of fillers to thicken. Sometimes I will mix a batch, wet the surfaces to be mated/filled/bridged then wait for the epoxy to thicken in the cup until it no longer is runny, then apply it with some sort of tool, possibly use the plastic over it and mold it as it thickens further.


Re: Softer, longer lasting Rain Gutter Seam Sealer?
wrcsixeight #724762 June 14th 2017 7:28 pm
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Originally Posted by wrcsixeight

I am not always so fond of fillers to thicken. Sometimes I will mix a batch, wet the surfaces to be mated/filled/bridged then wait for the epoxy to thicken in the cup until it no longer is runny, then apply it with some sort of tool, possibly use the plastic over it and mold it as it thickens further.


Iv found that epoxy in this thickened, or beginning to set up state, is super sticky and will not release or flow off of a tool cleanly. So I made a mold of the side gutter and will lay up up a replacement part first. Epoxy it in place on the van and then apply more layers behind to strengthen like I did on the back gutter.

My problem now, is I cant get 2" packing tape to lay smoothly in this concave mold. Mainly the drip edge. I had more luck with the wooden mold for the back gutter because the mold was larger, wooden, and I routered a 1/4" drip edge. The side gutter mold's drip edge is 3/16" and each time I try to apply packing tape, I get air bubbles and folds because the packing tape sticks so well to the epoxy mold. Maybe Im fighting it because this side gutter mold is so small, and my tape is 2" wide? Can I use 1/2" cellophane tape instead and meet two pieces inside the drip edge?

[Linked Image][Linked Image]

The back gutter is looking great! I have some sanding and a few air bubbles to fill.. But I bet at first glance you wouldnt know its been repaired when I'm finished..

[Linked Image]


If I wanted to post cure these repairs, how can I localize heating up to 130 degrees? I'm a bit worried about it softening in the sun even with white paint because when I washed my epoxy mold in hot running water, it became soft.

Thanks!


1995 E350 6bt/nv4500
Re: Softer, longer lasting Rain Gutter Seam Sealer?
rebar #724766 June 14th 2017 7:59 pm
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Post curing at higher strengthens the epoxy, but this is not really a requirement in this application in my opinion.

I would fear it might compromise the bond to the steel.

Applying the 'thickened by time' epoxy certainly is very time sensitive.

I'd use freezer bags for molding, not cellophane tape. The adhesves in the tape can remain behind and cause secondary bonding issues.

Sometimes bubbles or gaps are unavoidable. Once one decides to leave them, it is best to try and drill a hole and inject some more into the void somehow. Sometimes this requires a small drill hole top and bottom.

If the weave of the cloth does not want to bend as desired, sometimes pullmany individual strands from the cloth and lay they all in the same direction like an unbraided rope. I use a low of woven roving like this, just pulling larger individual strands. These larger individual strands can be difficult to wet out completely. helps to bend and flatten the roving over a smooth radius I will tape one end of the roving, and use a corner of the cardboard to lay the roving in and allow the epoxy time to saturate, then lift with one hand and squeeze out the extra resin.


Re: Softer, longer lasting Rain Gutter Seam Sealer?
rebar #744589 January 18th 2019 4:49 pm
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Hi guys, I'm new and a bit late to the conversation, but I used Dicor Self Leveling Lap Sealant RV Roof Caulk to seal the rain channel seam on the top of my 77' Chevy G20 Van. All the hardcore van living guys swear by it. It really settles into the all the cracks and seams and is also paintable. I bought mine from a local RV place, but it is also available online. I used 3 tubes on my van roof but it is best to buy 4 because you don't want to run out in the middle of the job. Hope this helps.....

Last edited by BushcraftVan; January 18th 2019 4:54 pm.
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