I’d heard that the ABS in Royalex can be seriously softened by solvents, such as the solvent in Vynabond, but I’d never seen it for myself.
After working on my Mad River Synergy-- a whitewater canoe not to be confused with the MR Synergy fishing SOT-- I left a quart can of acetone standing in the bottom of the bow. Yesterday I noticed an acetone odor, but did not recall that I had left that can in the boat. Today, searching for other tools I had used on the Synergy, I spotted the acetone can. It had fallen on its side, and the snap closure had slowly leaked acetone onto the Royalex.
Now there’s an irregular, 2" x 5", soft spot in the Royalex. The acetone cut right through the vinyl and softened the inner layer of ABS. The outer layer of ABS is not softened, yet, though if the acetone works through the foam layer, then the boat may have a very soft spot on both sides.
In order to allow as much acetone as possible to evaporate, I pricked small holes through the vinyl with a skewer. Some runny aqua fluid leaked out of some of the holes. That’s dissolved ABS.
I have everything I need to make a good repair, though I don’t know yet whether I will have to scoop out the dissolved ABS and foam. If the outside layer of ABS does not soften, I may not patch it at all, or I might put on just a couple of layers of S-glass. For the inside, I’ll have to fill any gaps in the laminate, and then maybe I’ll use the Kevlar/carbon weave I got from johnrsweet.com.
ADVICE: Don’t let solvents get at the ABS layer in your Royalex boat. Don’t assume that the vinyl layer protects the ABS from solvents. If you use Vynabond to glue on vinyl fabric D-ring patches, do not use any more Vynabond than recommended, and make sure the Vynabond is DRY on both surfaces. Any adhesive you use on Royalex that has aromatic solvents may have the potential to soften ABS. Consider urethanes, or the new G-flex West epoxy. (Just got my G-flex-- will report anything interesting.)
Before you go about patching it
Give the boat a week to harden up. The ABS should re-solidify and while it will be thinner than other areas, it probably wont need a patch right away.
Yeah, that’s what I’m hoping. I’m busy
outfitting another boat anyway. I’m a little anxious that if the amount of acetone invading the Royalex is larger than my initial estimate, the softened area could spread. But I’m just too busy right now to excise the softened area.
Be careful with bug spray
I sat a can of Off on the hull of my Dagger Legend while I was unpacking gear one day and apparently it was leaking. Withing an hour or so a had a can shaped soft almost mushy ring in the outer vinyl. I blotted it up and flushed it with cold water and eventually some soap to try to remove it all. It never re-hardened. After a month, I had to cut the bad piece of outer vinyl away and patch it. Fortunately it was small. No telling what would have happened if had sat that way overnight.
Just checked it today, and the puffiness
is down somewhat. The damaged zone is firmer.
dissolve and solve repair
Thanks for the info, g2d, and please let us know if it hardens again. Like nermal, it seems like I, too, remember reading that the abs will harden again when the solvent evaporates. I would expect that a litle heat might promote that process, and I would think something like an electric blanket or heating pad would be a safe way to apply it.
If it does eventually re-harden, and if one knew the proper qunatities and best choice of solvent to use, I wonder if could you use pieces from another royalex boat to reinforce or patch a damaged royalex boat?
For example, suppose you punch a hole in a royalex hull from hitting a rock. Could you cut out a piece of hull from a scrap boat, remove the covering layers over the abs, pour an appropriate amount of solvent on it to soften it, then press the soft abs into the repair area and let it harden?
That happened to me too
I put in knee pads one day in a Prospector and the next day ran a river with a bowperson who had medical issues and could not paddle. Needless to say we hit a rock head on and I was plenty mortified to find a big crease in the hull under the bow knee pad.
It was as soft as melted wax. It did harden over the summer and I was able to mold most of the fold out before the hardening.
Next time I will be MUCH more careful with Vynabond. I have no idea if the chemical composition has changed over the years as I have never had that softening before and I have used it in the past…perhaps way in the past. Or the ABS has changed?
I have been told to let the two surfaces dry thoroughly then press together with pressure and apply heat.
The inside is much firmer today, but
not completely hard. On the outside, there is no visible distortion, but there is a soft spot roughly 1" by 2".
There are people who have gotten quite skilled at grafting on ABS sheet, or dissolving ABS pipe and then painting layers on to effect repairs.
However, I’ve been working with epoxy and glass since about 1963, and so I’m very comfortable with it. Regardless of how hard the inner hull gets, I’ll put on at least two layers of S-glass or Kevlar/carbon. If the outer hull does not get completely hard, I’ll put a couple of layers of S-glass there also.
One issue is, what condition is the foam layer? That’s where the stiffness of cloth and epoxy is reassuring. It can bridge a soft spot in the foam.
yo memphis
I’ve got some links in links with this link :-0
http://www.npmb.com/cms2/e107_plugins/forum/forum_viewtopic.php?97767
I’m mattm on the other sites, and had great luck with Aarons Whitesell, cutting out the rotted foam and mixing up thick abs slurry. Got to put another thin coating on 2 Encores, a reflection, and the whitesell when the weather warms up.
Aarons the outfitter, and I’m the “toxic repairman” in our family. Converting the whitesell to tandem this year. Pretty cool when my teenage son is psyched to tandem with dad again. Whitewater single blading, what an awesome activity!!
ouch!
sorry about your luck. I try and keep ALL solvents and Royalex as far apart as possible!
sounds like it has hardened up a bunch and hopefully won’t be too much of an issue / repair!
good luck!
steve
skid plates
Oh yeah, you’re very lucky if your son likes it. The older they get, the harder it is to get them to look up to you, but outdoors stuff always seems to be a pretty reliable resource. Watching and teaching your boy whitewater skills could re-enthuse you all over again.
Thanks for the info and the infinitely regressing series of links. 
So this has been known for quite a while, then. I wonder why people don’t use abs and the acetone-solvent method to add skid plates, etc.? I guess part of it is the horror of purposely applying solvent to one’s canoe and seeing it soften up, if only temporarily. Second, scraping off the vinyl probably is a bit of a bear, too. And third, if you have to wait a week or more between layers, it could put you out of commission for more than a month.
But still, US Plastics sells a 4x8 foot sheet of 1/16-inch thick abs for $35. If you cut the sheet into 16 pieces 6x48 inches and apply progressively overlapping pieces along the keel of a 15-foot canoe, you could build up a very sturdy spine over ¼-inch thick at the thickest places. Assuming it bonds well to itself and to the original abs, that would be a much stronger skid plate for less than 1/3 the cost of other methods.
Can you give any guidance as to how much acetone to use? If working with 1/16 sheets, maybe use a paint brush for application and apply one/two strokes at a time until it softens? How long does each layer take to dry and harden?
I also like the idea of making a “slurry” mixture of abs and acetone and “painting” it on weak spots.
Anybody have any further thoughts or warnings on this? What’s the best way to reapply the vinyl or other covering coat?
Also, is all ABS the same thing, or are there different types? I’m assuming it’s all the same.
a little info. 
firstly, Aaron is twice the paddler I'll ever be, as Eckilson, Mintjulep, Tommy C1, and Spiritboat are aware!
As far as skid plates, I don't think you'll want to intentionally soften the royalex. What i've done is paint the slurry on the ends, this way the acetone evaporates before softening the parent material. Thin coats are better for adhesion, I made a putty like mix for the hole repair. The acetone will evaporate real quick, so as I paint it on I add some to the slurry to keep it viscous.Work fast, this will solidify real quick.
Also very important if you're down to the foam layer not to have the acetone contact this. Use the gorilla glue barrier.
I generally fill a well sealed jar (mayonaise/glass/screw top) about 3/4 full of the pellets(cutting up the rod), then add acetone to just cover this. wait about 2-3 days. recoat can be near immediate as drying time is real quick. have several cheap brushes handy.
Good points. If one needs to remove
the vinyl layer, it can be done easily with a sharp 1/2" chisel. Hold the chisel at as low an angle as possible, and push steadily with the blade at a small angle to the direction of pushing.
The chisel blade will go down through the softer vinyl, and will skim the vinyl off the harder ABS. It goes better if, after taking the first removal stroke, you overlap strokes as if you were cutting the lawn.
Saves sanding, avoids accidentally sanding into the ABS.
It is true that liquified ABS can be painted on solid ABS, as long as the solvent in the liquid can evaporate readily so it does not travel into the solid ABS.
acetone and Royalex
I’m no chemist, but I do know that acetone is extremely volatile. I believe that most of the damage to your canoe was done while the rectangular can held a pool of liquid against the plastic. Without the can there, the pool would have evaporated much faster, and less damage qould have been done. As it stands, I don’t think you have to worry too much about on-going damage, as the residual acetone probably evapotrated fairly quickly after the can was removed. What is left is dissolved and partly dissolved plastic. If it doesn’t harden after some time, you might need to cut or scrape it out, leaving the outer skin intact if it is not badly damaged, filling the hole with kevlar or fiberglass cloth and/or an ABS sheet plastic patch and flexible epoxy. It could be a very neat patch.
Yes, but…
I agree it’s a good policy to keep solvents away from plastics, In most cases, but there are times when there are reasons to use them. For example, used boats often have state boat registration numbers glued or painted on the hull. If I buy one, I’ll probably need to use a solvent to remove the numbers. Of course I’d like to do as neat a job as possible. I think brief exposure to solvents, such as to remove paint or cement, will usually be OK, as long as the exposure is brief. The solvent should not be permitted to pool on the plastic. I would expect that a solvent might dull the surface at worst, by slightly dissolving it. Of course the effect may vary between solvents.
Any one know differently?