how to layup with vinylester correctly?

Hi,

I've got some coosa parts that are getting glassed into existing hull structure, stringers mostly and some small bulkheads, which I'd like to use VE for. I've got a 5 gallon bucket of a vipel VE, not sure which vipel formulation exactly but was told it was unwaxed and for hand laminating at the supplier, who is a good supplier but isn't a boat builder.

What I'm second guessing with the stuff is when you have any thickness at all of the resin, ie anything more than what you might swipe on with a paint brush, it maintains no tack whatsoever. A real thin layer that doesn't generate any heat seems to maintain some tack for awhile on the side exposed to air (like this morning I noticed my test from last night, peeled it off the plastic I put it on, top was tacky bottom was not).. For instance comparing it to polyester, with polyester I could tell the difference between waxed and unwaxed, it's obviously tacky when unwaxed after sitting for months even, where the VE with any thickness to it is 100% cured to the surface from what I can tell.

My usual laminating process with polyester, since I do it in between a day job, is I show up some night, say a Tuesday night, add a layer. Then I come back on another night in short proximity, say the following Thursday, and add another layer.. With 2 part epoxy I may time things so I can come back in the AM and get a 2nd layer prior to full cure but if it cures I clean & sand...

So my question is basically, with the VE, if I come back in 24 or 48 hours after I lay it up and it is tack free, do I need to sand? Or does it bond to itself just fine without sanding for some period of time? How do people normally work with this stuff, do they put all the layers on in the same day to achieve a chemical bond? What's different about the process versus polyester?

Thanks in advance!

Jon

 

The exact resin formula makes a big difference, most VE's tend to be slightly sluggish, so in a thin film they tend to be rubbery, but even in a thicker laminate the surface doesn't cure tack free quickly, so a day or three is normally Okay. If this is a skin resin (used for thinner laminates and designed to cure quicker), then it's possible for it to be tack free sooner. Also many skin resins are a blend of VE and DCPD, VE doesn't like to cure, DCPD cures easily and will cure tack free quickly, possibly creating bond issues. Is there a resin code on the pail, or can you get it?

Most resins are good for at least 24 to 48 hours with no surface prep, others for a week or more.

 

Thanks!

It didn't say on the jug but I just called and the supplier had that immediately, F010-TBN-23.

 

I'd definitely say - thin film, rubbery, thick film tack free, kinda 2 modes. In my application will be laying up 1708, what I should do and I will tonight, is saturate some 1708 to see what the effect is at that thickness too.

 

http://www.aoc-resins.com/images/uploads/F010 Series_us_1.pdf

Straight VE. It would be normal to wait a day or so before applying the next laminate, but see what your test result indicates. A laminate will have a different feel on the surface than a puddle or thick layer of just resin.

 

Ok thanks! So you are saying it may feel sticky 24 hours later when I try with it a laminate versus resin sitting in a pot?

Should I be using the "feel sticky" test for knowing if I can laminate for a chemical bond versus there is a need for prep, or do you figure I should go at it based on timing, or some other test?

Jon

 

The touchy feely method works about as good as anything, dig your finger nail into it, while it may feel hard at first, your fingernail still may dig in just a touch.

 

Thanks again!

Update - I did conduct a test, wetting out some 1708 samples with the VE. 24 hour mark, a little sticky but not to the point where it comes off on your hand like PE would, can get a nail in, looks sanely bondable. 36 hour mark still can get a nail in but feeling less obviously sticky; at the 48 hour mark tonight I'm going to laminate over it in a lap and when it cures will try to peel apart and see how it worked. Weather has been fairly warm, averaging 80 degrees where I'm doing this; I mixed it at 1.5% hardener.

One thing that's come to mind and would appreciate anyone's take on the idea, is I'm considering doing my initial layer w/ the VE, followed closely by the 2nd layer using standard ortho PE. The reason for this consideration is I'm really using the VE to help promote the initial mechanical bonding as well as I can, not so much for strength as the PE would be strong enough, and I'd like to buy some additional chemical bonding window; seems like it'd be the best of both worlds, VE bonds to the original structure, get a chemical bond with the next layer of PE, then I have extended my time I can go in between layups and am working with the less expensive resin. What do you think?

Jon

 

I know this is an older thread but it is a very relavent one to me as my son is laying up some parts with 1708 and unwaxed VE and he just called me with exactly the same question as yours and I really couldn't give him a confident answer, the open time has been about 48 hrs and it really is not sticky so he is going to sand it even though it gums up the paper and then wipe with acetone before continuing. If it were poly, particularly ortho it would be a go. Its a bit frustrating so I would like to find a definitive answer which may mean going to the manufacturers tech support, in this case Ashland I think.
How did that PE over VE test go? I know a lot of boat manufacturers do this for the added protection from osmosis so I assume it works. I had always assumed that they were using PE for the subsequent layers after the VE skin coat just to save money but maybe it is, as you say, for a longer open time between subsequent layups.

 

The open time can be long with VE, frequently a week or more and the bond will be fine, a day or two is nothing.

DCPD resins, or other resins blended with DCPD will cure much quicker on the Surface, and in a few days the bond may be poor. Straight DCPD has the shortest open time window, but it can still be a day or two if the conditions are right. Cool temperatures, higher humidity, no UV exposure and a clean environment will lengthen time for a good bond.

I never wash the surface with acetone, you're removing the uncured surface that you're relying on for the bond. If it's gumming the sandpaper the bond will still be good.

PE and VE are 100% compatible, you can even buy blends of the two. You can blend DCPD, ORTHO, ISO and VE resins in any combination for the desired result.

 

ondarvr obviously knows, no question on that...

What I found w/ the VE I'm using (exact formulation mentioned above) is I feel good without prep for 48 hours, not saying it's not good > 48 hours but at that point I usually prep via sanding w/ 40 grit.

It's cure is very much all or nothing - when it wants to go, almost regardless of what hardener ratio within the recommended scale, it goes quite quick compared to PE. Alternatively if you run it much outside of it's temperature range, like say < 60 degrees it cures very slowly and down below 50 I'd say it will not cure reliably no matter how much hardener you put in it. My take after a little experience with VE - temperature is extremely important, run it at 70+ degrees. I've heard the specific VE I'm using stays sticky forever (from the supplier) but actually I'd say if left in conditions where it cures quickly it seems to come full cure to the surface in 4 days, or at least to a cure drastically more complete than unwaxed PE would; I think the feedback he gets is from people who do not run it in the right temperature ranges, which is very easy to do up north where I live as it's only a couple months of the year where it's warm enough 24/7 to hold 70 degrees without heat.

Polyester over VE in a chemical bonding situation is both good on paper as it was when I did some tests. Fairly typically I will put my 1708 tabbing down, let that cure until the next day, then I will sand down any sharp spots and run a veil of mat over it with PE; the mat runs much nicer with PE and sometimes I find by getting greedy and attempting to completely finish the spot in one sitting I can screw up the underlying layers when they are curing but not cured to the point where they stay put, so instead of waiting I quit and come back later to finish the job.

Jon

 

Thanks guys, like majic, you respond to an old thread and it comes back to life. This is a very good thread in that it didn't get a lot of responses from a bunch of folks without any knowlegable input to muddy the waters. I don't think those who wipe down with acetone are actually going at it enough to actually remove the uncured surface, from what ive read from others in the trade, just a quick wipe to make it sticky again, it would take some serious multiple rag scrubbing to actually remove the stuff over a big area, but I take your point and i would rather not do any more work if its not necessary myself. Its good to hear it from someone who's opinion you respect on the subject. Its also good to hear that PE and VE are 100% compatible because it is common these days for production builders to do the skin coat with VE to protect from osmosis and then the rest of the layup with PE to save money which clearly works but a few years ago when i made the suggestion on a forum somewhere that it would be possible to set up your female hull mold with your resin feed lines strategically placed so that you could infuse with VE up to maybe 6" above the waterline and then use PE from there on up to the sheer no one thought that was a good idea.
Regarding DCPD resins I have heard of these but really have no idea what they are and why you would use them, so perhaps you could educate me if that would be ok. I've used ortho, iso and VE but I really don't know where this DCPD fits into the picture.

 

DCPD is a resin base that was very low in cost at one point, plus it had comparatively little shrink and good water resistance. The down side was it was brittle and the surface would cure so thoroughly that secondary bonding was an issue. This resulted in some real issues in production when they used it like a straight ORTHO or ISO where you could come back at anytime and have very good secondary bonding.

Now most of the resin used in the industry is a DCPD blended with an ORTHO or ISO, more often with ORTHO. This was originally to lower the cost, but the cost of DCPD has gone up over the years. The big plus for production builders is that DCPD requires less styrene to lower the viscosity to a point where it's easy to use, at the lower styrene content the other resins are almost unusable. Styrene content is limited to 35% for typical production resin.

Other stuff,

VE's tend to be a little sluggish when it comes to curing, so they try to kick it in the butt a little with the formula, but at lower temps it still doesn't like to cure very well. Plus the gel time tends to drift out longer, so they may make it a little quicker so it will be usable longer. This may be why you see so much of a difference with temperature and laminate thickness compared to polyester.


There are generalities for each resin type, each individual resin will have it's own characteristics.

 

Something else worth mentioning - as far as VE skins & polyester resin, VE, ortho or iso, blends etc.. etc.. With the boat I'm building the builder (who molds the hull & top, at which point you can take the hull as a "kit" and finish it which is what I'm doing) was alright w/ a VE skin but simply does not see any benefit to and wants no part of, building a hull using only VE resin. He is very sure that it's a waste of $$ and adds that his crew would kill him for making them do it, which I suspect also makes him uneasy about quality control and simply doing things which are untested in his ~35 years of building fiberglass boats...

As far as why people hate using it - everyone cites the fumes, I kinda don't get that as the filters take them out as good as the PE fumes but maybe they do some things via fans/venting and the VE does not allow for it. The foam VE can create can be more of a problem, as can working times, it being fickle with temp, all that I can see.

My own opinion - and I'm a student at the absolute best of my experience - is that when you have something that runs > 100K in parts alone the ballpark $5000 upcharge on material (on my hull which I figure is ~250 gallons of resin estimate by it's weight, add $20/gallon for VE upgrade) really isn't all that outrageous for what you get. But they would need to be more careful building it, which maybe adds labor, and is probably why they don't want to do it in the first place.

Jon

 

VE's tend to be a little harder to work with, but it depends on which one you use, some are better than other's.

The odor is a bit different, but I don't mind it that much, and again, they don't all smell the same.