Delamination Prevention

[OSM]

We currently have a hull that has been in the mold for about one year. The next step in the process is to install the stingers and support system.

I've heard that washing w/acetone will not be effective at this time and should wipe w/styrene instead. We do plan to sand/scuff the areas with 36 grit paper but dont want to spend any time on this project if the end result will be delamination.

I welcome your thoughts.

[buckknekkid]

I would consider it the same as a repair on a one year old boat. Sand and grind, pleanty of acetone and lay it up!

[fiberglass jack]

i would wash with styrene it will reactivate the old resin ,wait a hour or two after the styrene has dried, the old resin should feel tacky i always wipe down with styrene if i have skined a mould I find that u get a chemical bond this way and with acetone you are only washing off the dirt and grime and only getting a mechanical bond but i would sand with some 36 or 40 before you wipe it down

[fiberglass jack]

one other thing did you guys lay the hull wiyh polyester if so you could always use a transition resin say derakane which is a vinyalester just brush some on after you have cleaned and wipe the hull down this will give you a good foundation. another trick to see if you will have a good bond is to get some 24 oz woven roven and lay up a strip down where you are placing the stringers ,now leave a good 3 foot tab at the end that is dry tie it to a strong handle or to a hook and pull it off or should i say rip it off the woven roven will come up but will leave some down dont sand this but rather leave the expose glass as a bonding medium for the new glass its a work out but if you use a chain hoist its a peace of cake OR YOU COULD BE LAZZY LIKE ME AND JUST INVEST IN SOME EPOXY

[buckknekkid]

ya, like he said!! Good idea Jack

[OSM]

Thanks for the input. I will follow your advice and wash the area with styrene after sanding/grinding and cleaning with acetone.

[jimslade]

I would grind with 24 grit. There should be enough styrene in the resin to reactivate the old. Use 1% mek to allow the new resin to set properly. I did the same work on a hull except the boat sat in the hull frame for 18 years!

[ondarvr]

As a resin supplier my recommendation is to sand it thoroughly with at least 36 grit, and then clean the surface. Styrene and acetone have little effect on the cured surface other than cleaning it and won't really help the new laminate bond to the older one. There is no way to reactivate resin, if it's cured it's cured, although resin doesn't crosslink 100%, so there are still sites that can crosslink between the new and old resin, but it's mostly a mechanical bond. Like FJ said, a VE resin will bond better and even a brushed on coat will help, but a layer of mat with VE resin would be better and would be an easy way to increase the strength.
Styrene can soften a low molecular weight resin, or a poorly cured resin, but either one of them would build a poor quality hull. I know that a styrene wipe is a popular idea and has been around a long time, but I checked with two of the resin chemists in our lab before saying anything about it here. Both chemists said a styrene wipe would do little or nothing to improve the bond other than cleaning the surface. I will try to enter a lab project for them to test it again, I would like to see the results also.

[buckknekkid]

Originally Posted by ondarvr

As a resin supplier my recommendation is to sand it thoroughly with at least 36 grit, and then clean the surface. Styrene and acetone have little effect on the cured surface other than cleaning it and won't really help the new laminate bond to the older one. There is no way to reactivate resin, if it's cured it's cured, although resin doesn't crosslink 100%, so there are still sites that can crosslink between the new and old resin, but it's mostly a mechanical bond. Like FJ said, a VE resin will bond better and even a brushed on coat will help, but a layer of mat with VE resin would be better and would be an easy way to increase the strength.
Styrene can soften a low molecular weight resin, or a poorly cured resin, but either one of them would build a poor quality hull. I know that a styrene wipe is a popular idea and has been around a long time, but I checked with two of the resin chemists in our lab before saying anything about it here. Both chemists said a styrene wipe would do little or nothing to improve the bond other than cleaning the surface. I will try to enter a lab project for them to test it again, I would like to see the results also.

You need to post more, its always enlightening to hear from the tech boys. Saves a lot of grunt work and builds a better product, Thanks Buckk

[fiberglass jack]

Ray we all know you love the grunt work

[buckknekkid]

Dust is my mantra

[fiberglass jack]

I knew there was something not quite right with you

[jimslade]

When I do restoration work on old vehicles(40 years plus) I always have to remove the old filler. The new styrene in the filler softens the resin in the old filler and when you file, the old filler can soften up. The problem with polyester resin is that it is in a constant state of cureing. If you take an old white boat and paint it black the heat generated by the black paint will start to cure the resin even harder and the boat will now have distortion down the length. Only epoxy will not distort after years in the heat. I can soften up old filler by heating it up nd you can smell the styrene that has been trapped in the resin being released. Let it cure again and it will be brittle. Just my experiance. My son is also chemistry student. I will check with him for answers.

[ondarvr]

JS

That's why body filler is not a good option for any project that requires strength or heat and water resistance. The resins and fillers are chosen for their fast cure, easy sanding, low cost and little else.

[Russ]

Hi guys, just a point for consideration.
If you are repairing below decks, say in an engine room or where oil or grease is present NEVER sand before cleaning. The oil becomes groung down into the fibers and even if it looks nice, the adhesion will be compromised.
Oh yes, one other thing. ALWAYS be sure the boat was not built using "low profle" resin. There is DCPD added to give quick hardness for faster demolding. Wonderful? yep, except that the chemical bonding sites in the resin only give you a few hours to tab.