Vinyl Ester and Polyester Used Together?

[tpenfield]

This might be an @ondarvr question, and maybe a few other folks . . . about using Vinyl Ester and polyester together.

I have seen some posts that they are compatible, but I wanted to ask about using VE resin on the bonding surfaces and polyester 'putty' in a gap-filling application on my extension bracket project. (see my active project thread, as desired)

I have polyester hull & deck 'adhesive' (putty)
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Which I am going to use as a gap-filling adhesive when I attach the extension bracket to the hull of the boat. The gap between the 2 pieces will range from 3/8" to about 1/4" , so too much of a gap for 5200 style adhesives IMO.

I was thinking of pre-wetting the mating surfaces on the hull and the extension bracket with a light coat (brushed on) of Vinyl Ester resin, then apply the polyester putty in liberal amounts those mating surfaces just before mating them together.

My concern is if I do not pre-wet the surfaces before mating, the process will rely on the 'putty/adhesive' to wet the surfaces as they are mating, which may not happen to the greatest extent desired.

Just wondering if VE resin slightly pre-wetted on the surfaces will provide an adhesion advantage?

T. I. A. for any guidance on this. Maybe I can test this?

 

[ondarvr]

They are 100% compatible, you can even blend the two resin types together to achieve different results for certain projects. Wetting out the surface slightly with VE will help with bonding, and adding a bit of VE to the bonding putty may make it easier to work with. This just depends on the viscosity of that exact putty and how you want to use it though.

 

[tpenfield]

They are 100% compatible, you can even blend the two resin types together to achieve different results for certain projects. Wetting out the surface slightly with VE will help with bonding, and adding a bit of VE to the bonding putty may make it easier to work with. This just depends on the viscosity of that exact putty and how you want to use it though.

OK, thank you for the validation on the compatibility. I currently have a test sample curing, so I'll see how that goes.

One challenge that I am anticipating when I use the putty for real is that I'll need to quickly mix 3-4 gallons of the stuff (I have a 5 gallon pail of it) and apply to the mating surfaces before it starts to cure. I figure that I can pre-wet the surfaces with the (activated) VE and then activate the poly putty. Perhaps I'll be using my masonry tools to handle that amount of putty all at once.

 

[tpenfield]

Here is the test piece that I made using VE brushed on the the mating surfaces and then the putty applied in between.
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It certainly bonded . . .

 

[kapnD]

Are you going to test it?
Drive a wedge between the pieces and see where it splits.

 

[fallguy]

I’ve never bonded two structures with resin alone on vertical surfaces as gravity is a problem.

The only methods I know are epoxy thickened with cabosil or wetted fabric.

I am a wee bit confused about your approach. It seems like you are doing two things. First is making a contact surface with fairing putty. Then you would remove the extension and make the fairing more perfect. Then you would bond the extension to the hull with say a piece of wetted 1708 between the components and bolt them together. The glass prevents crushing the resin out and prevents it from running down vertically.

I would hope you’ve allowed for some tabbing of the extension to the hull as well.

You may use something like a 3/8” square trowel for the initial fairing; then attach with plastic on the mating surface. Then cure and fill the voids flat. This would also cut down your putty work to 50% in theory; the risk is too much putty, so you have to really dial in the trowel needs.

Perhaps Ondarvr can expound on the best way. I trust his wisdom. I know zilch on VE/PE and know nothing about their viscosity on vertical surfaces.

I suppose some mechanical fastenings used during the bonding process could also be left in place.

 

[gonzo]

The resin is for pre-wetting the surfaces. It is not usually necessary. Structural bonding with putty is very common in many applications.

 

[ondarvr]

One key to a good bond is thoroughly wetting out the substrate. Much of the resin in structural putty is used up wetting out the fillers and fibers, so less is available to wet out the substrate, and the higher the viscosity of the putty the less resin is free and available.

It isn't always important, especially if the bond isn't stressed to a high degree, but when water comes into play the bond line sees stresses in a different way. I did testing on swimming pools and hot tubs, plus below the waterline in marine applications and the bond holds up significantly better with resin applied first.

Even with good marine base resins blisters can form if putty is used directly onto the substrate, especially when in contact with gel coat. The pool & spa industry and the marine industry got in the habit of applying putty directly onto the the back side of gel coat to any tight radius that may be difficult to roll the air out of. This worked great in production, but after a few years there were lines of blisters at the gel coat and putty interface. A quick application of resin prior to applying the putty eliminated all blistering. And the longer the resin sits on the surface in an uncured state the better the bond because it can more thoroughly wet out the surface.

 

[tpenfield]

I have a follow-up question to the VE/poly combination. . . .

After doing the poly putty & VE to pre-wet the bonding surfaces, I had some of the poly putty left over (maybe 3/4 of a gallon) I added about 1 quart of VE resin to it along with some fiber strands and silica filler to make more putty. I'm just wondering with this 'Franken-putty' would it have the adhesion & strength more along the lines of VE, or somewhere in between the characteristics of poly & VE? Is there a point where the characteristics cross over?

 

[ondarvr]

The actual strength can vary, but it will be somewhere in between the two.