Mixing Small Quantity of Hypalon Cement

[waterman46]

Just got a new package of 2 part Hypalon cement and the accelerator. Supposed to mix it 25:1. I only need a small quantity for the repair, maybe 1 tbsp. No info is given on mixing small quantities, either in the Polymarine web site or on the package.

It would be nice to know how many drops of accelerant are needed with 1 tbsp of the cement. I think the size of a drop of accelerant might be smaller than a drop of water so I probably shouldn't use water to find the number. And I don't want to contaminate the accelerant by counting drops into a tablespoon measure then putting that back into the bottle.

Polymarine says wait 30 minutes between the first and second coats. Can I use mixed cement from the first batch for the second coat or do I need to make a new batch? Unbelievably there is no info on pot life from Polymarine.

I just posted these two questions on the Polymarine web site but not sure how long it will take for them to answer, if ever.

[MarkJ]

Yes, its nigh on impossible.

One truck I have is to use a syringe. Cheaply available at a chemist I ask for a small one... the same size heroin uses use. I have just got over my embarrassment of asking for them

Other trick I use is to mix it for a full 5 minutes. Time it.

[fstbttms]

I quit screwing around with the 2-part adhesive. The single part stuff works great and is so much easier to use.

[waterman46]

The syringe is a great idea - I already have some I use for loading printer ink.

One part cement? Maybe I don't use the right prep or whatever, but I can peel off the patch, after letting it cure a few days, if I use the one part cement. OK for small holes but I need to patch up a 3" cut.

That 3" cut was my own doing. I followed instructions for replacing a valve, where one of the ideas on the Polymarine site is to cut a 3" slit in the tube near the valve and remove it that way. Turns out its a super stupid idea. Instead, you can just cut about 1/2" radially on each side of the valve itself, and pull the old valve out through that. It's easy to repair the small 1/2" cut by making a circular patch, with a hole cut in the center for the valve to pass through.

[RaymondR]

Pipettes with rubber bulb suckers if you want to get really precise. Usually available from laboratory suppliers.

[fstbttms]

Originally Posted by waterman46

One part cement? Maybe I don't use the right prep or whatever, but I can peel off the patch, after letting it cure a few days...

I've got patches that have held up for years.

[bruce v]

[QUOTE=waterman46;2196985]The syringe is a great idea - I already have some I use for loading printer ink.

One part cement? Maybe I don't use the right prep or whatever, but I can peel off the patch, after letting it cure a few days, if I use the one part cement. OK for small holes but I need to patch up a 3" cut.

That 3" cut was my own doing. I followed instructions for replacing a valve, where one of the ideas on the Polymarine site is to cut a 3" slit in the tube near the valve and remove it that way. Turns out its a super stupid idea. Instead, you can just cut about 1/2" radially on each side of the valve itself, and pull the old valve out through that. It's easy to repair the small 1/2" cut by making a circular patch, with a hole cut in the center for the valve to pass through.[/QUOTE

As I also had a problem with the one part adhesive sticking and adhering after "curing" I kinda tossed it too. However, while surfing the net, I ran across a hypalon boat building video and found it very enlightening. As these guys do it for a living, thought their process should be considered. Interestingly, they use a single part adhesive too. Things I found as to why I couldn't get it to work.
1. Are you working with hypalon or PVC - they are not the same and require
different adhesives
2. It is absolutely mandatory that you rough both the area to be patched and
the down side of the patch thoroughly
3. Wipe the patch and the area with alcohol or MEK to clean after roughing
4. Apply a light coat of adhesive to both patch and patch area and let dry to
tacky prior to attempting to bond.
5. Roll out all bubbles thoroughly making sure edges are firm
6. Let sit 24 to 48 hours (this is the hard part) before airing to test bonding

Yes, it will work and buying the right bonding adhesive (be it 1 or 2 part), knowing you have the right material and doing it yourself sure saves a lot of monies. I had a couple of dingies repaired professionally or should I say attempted as it cost $300 for one and the other delaminated so they said it was beyond repair (actually they felt it was to much work for the value of the boat). The one the did repair, they put a patch (unneeded) on a tube seam that did not leak in the first place and avoid repair to the hole I had pointed out - unfortunately I didn't test it until I travel across country in my RV and threw it on a small lake to go fishing - again my error. Learning from ones mistakes is a valuable tool - especially when we can benefit from the www for research. I ordered a hypalon kit on line for $25 fix my own and am now a happy camper. Hope this helps you with your dilemma. Bruce V

[svgypsyqueen]

25:1 ratio of Polymarine hypalon two part adhesive means that you need to use 1/17th of the total quantity of catalyst for your one tablespoon of part A. That is assuming you have the 250ml can of adhesive commonly sold.

The adhesive is packaged in ratio... so 1/4 can of part A uses 1/4 of the available part B.

250ml is approximately 17 tablespoons. (16.9) so one tablespoon of A requires 1/17th of the part B.

If you have three pieces of scrap hypalon... Glue together two pieces with the first batch and then glue the third piece to them with the second batch. This way when everything is supposedly done curing you have a test coupon to try to pull apart and confirm you have mixed properly rather than futzing with your patch on the dingy.

I would recommend against reusing the old batch with a new batch idea. You will not likely get a consistent mix between old and new. But I'm possibly a little anal that way....

Be cautious using a syringe. Many of them are lubricated with silicone oil which will contaminate your adhesive and possibly cause the bond to fail.

Rinse the syringe with acetone or a small amount of MEK to remove the oil. The down side is it won't glide as nicely.

Good luck and let us know how it turns out.

[Scaramanga F25]

For 25 to one = 8 drops per tablespoon.

[MarkJ]

Originally Posted by svgypsyqueen

Be cautious using a syringe. Many of them are lubricated with silicone oil which will contaminate your adhesive and possibly cause the bond to fail.

.

A medical syringe wouldnt have silicone oil, or anything else in it, surely?
Or is tgat why i still twitch after seeing the doctor?

[michaelratinter]

1/8 teaspoon gives 24:1 close enough?

[Sandero]

If anyone is interested in hypalon 2 part glue and several large pieces of gray hypalon... message me

[svgypsyqueen]

Originally Posted by MarkJ

A medical syringe wouldnt have silicone oil, or anything else in it, surely?
Or is tgat why i still twitch after seeing the doctor?

Could explain the twitch!

All I know is that when mixing cobalt accelerator into epoxy paint if you use a monoject syringe without rinsing it first you will fisheye the crap out of whatever you are painting because of the silicon oil.

[Bulawayo]

I always just guestimated mine and didnt experience any issues. We have also used Sikaflex to stick down patches successfully.

[Jim Cate]

Have not used that specific adhesive, but with Rema Tip-top SC-2000, my all time favorite Hypalon glue, I found that putting the mixed up leftovers into the fridge in between coats kept it usable for an hour or so. May need to add a couple of drops of thinner (toluene in the case of SC-2000) to regain the proper viscosity for coating.

Jim

PS: for the SC-2000, the mix ratio is not critical. In fact, it will cure without the hardener added... just takes longer.