markcrnll Posted September 20, 2020 Report Share Posted September 20, 2020 So I've been doing all kinds of research and watching tutorial videos on polyester resin, epoxy resin and pour foam. I'm doing an up incoming revision on my audio build (reference pics of current state of build can be found in Mini Monster build log). I will be walling my already "illegal no wall" and using pour foam on both sides of the enclosure between the stunt wall and the speaker wall and plywood on the roof. My plan is to make a resin filler to put radius' on all my corners/ angles for the transition from the wall to the roof. Then resin the roof, the wall and over top all my filler before doing some surface finishing. To date the only experience I have is with 3M fiberglass resin (polyester resin w/ wax added) with a fine sand added. I've gotten the hang of things on using that like seeing how it reacts to different amounts of hardener, not making a mess, how long it takes to dry, how it sands, the rigidity, texture, amount of working time before tacking up, etc. My plan the first time was to use cheese cloth for a build up but the cheese cloth kept falling off (was trying to apply on a roof) so I just used the resin mixed with sand and went to town with that. I may be using some glass mat this time and may try spray adhesive to hold the mat down while laying the first coat of resin if I'm faced with a similar circumstance. I've been turned on to US Composites website and have learned that there's a lot more to the resin world then just 3M. There's different types of polyester resin like vinyl polyester resin, polyester layup resin and general purpose resin. Then I found out about epoxy resins, that come either thick or thin and have different strengths of predetermined hardener to activate.... So here's where I'd like to get input and have some discussions about. What kind of resins do you guys prefer for car audio builds? What do you like about the kind you prefer? What are your experiences and applications? I had good luck in the past with making surfaces more rigid, am I on the right track for creating rounded corners and rounded, smooth professional looking transitions on angles and surfaces like the seasoned veterans in the car audio community and custom audio fabrication shops do on their nicer looking wall builds? No experience or knowledge on this subject is too insignificant. I'm having a lot of trouble finding information on these specific applications for resins, it's taken me forever to come up with the ideas I have given I have no one to really ask... I will be using pour foam on the sides of the box. I have no experience with pour foam as the only thing I've ever used is spray expanding foam. I hear 16# density is the best. I've seen some impressive videos on YouTube using 16#. However I'm needing to fill about 6-8 cubic feet. That's $300-$400 in 16# pour foam. Has anyone ever used 8# or 4# density? Those would only cost $100-$225 to fill the space I'm wanting to fill. Is it effective in our application? How would one trim the 16# density foam? It appears to be as hard as stone... The buildup will be about 3 feet high, should I pour in layers? All at once? Is pour foam sticky like spray foam? Do they make air pockets like spray foam? What's everyone's thoughts???? Link to comment Share on other sites More sharing options...
pnutz37 Posted September 20, 2020 Report Share Posted September 20, 2020 I can't respond to the fiberglass portion but I can speak on the polyurethane foam. If you're using pour foam, you can do it all at once. The issue with the pour foam is knowing the pour rate to where you get to the expansion you want. You can do it with layers (Ideally you do it all in one). You may want to fill most of the void with pour foam and use spray foam to work the areas that you'll have to do cutting and trimming. 16# foam will be nasty to cut and shape. If you're using 4,8# you want to spray foam in passes (2-2.5" per pass). Not doing the foam in passes could cause the foam to self ignite (This is not the case in pour foam). The reason you do this is because of the exothermic reaction of the foam. Let the foam cool for 5 minutes or so between each pass (10-15 minutes is ideal). The other issue with not doing passes is the off-gassing. You could be trapping the gasses and it will continue to off-gas because the gasses can't escape (You can see the foam "horror" stories for work done on houses where they continued smell after install). The foam will be inert 24hrs after install if completed correctly. Link to comment Share on other sites More sharing options...
markcrnll Posted September 20, 2020 Author Report Share Posted September 20, 2020 2 hours ago, pnutz37 said: I can't respond to the fiberglass portion but I can speak on the polyurethane foam. If you're using pour foam, you can do it all at once. The issue with the pour foam is knowing the pour rate to where you get to the expansion you want. You can do it with layers (Ideally you do it all in one). You may want to fill most of the void with pour foam and use spray foam to work the areas that you'll have to do cutting and trimming. 16# foam will be nasty to cut and shape. If you're using 4,8# you want to spray foam in passes (2-2.5" per pass). Not doing the foam in passes could cause the foam to self ignite (This is not the case in pour foam). The reason you do this is because of the exothermic reaction of the foam. Let the foam cool for 5 minutes or so between each pass (10-15 minutes is ideal). The other issue with not doing passes is the off-gassing. You could be trapping the gasses and it will continue to off-gas because the gasses can't escape (You can see the foam "horror" stories for work done on houses where they continued smell after install). The foam will be inert 24hrs after install if completed correctly. Very interesting. What is this pour rate your talking about? Link to comment Share on other sites More sharing options...
pnutz37 Posted September 21, 2020 Report Share Posted September 21, 2020 Meaning the time it takes for the pour foam to set (it’s a delayed reaction vs using a spray foam where you spray 1/8-1/4” and it only expands to 2-2.5 inch). If pour takes too long to set it will expand later and longer. Tougher to figure out when to stop pouring. If it starts setting too soon, the opposite. The other thing is the mixture. If your iso / resin heavy it will change that as well. Good to test pour in a bucket to get an idea. Link to comment Share on other sites More sharing options...
markcrnll Posted September 23, 2020 Author Report Share Posted September 23, 2020 Anyone got anything else? I know some of you guys out here demoing 162+ got the knowledge on this subject that I need. Link to comment Share on other sites More sharing options...
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