New Glass Technique

I was attempting to explain a glassing process that I have been using for a number of years now to a friend and realized that not many fabricators are using it (at least to my knowledge). So I thought I would share here and see if anyone has any twists to add to it.

I start with an MDF skeleton (nothing new here). I then wrap a thin cardboard (known as "chipboard" in the upholstery industry) around the parts that I want to glass.












My favorite part of doing it this way is that there is vert little glass and filler to be done on the surface. The back of the chipboard can be reinforced if need be.

Complex shapes that would normally require expensive and time consuming foam can be made this way.






I have found that if you rabbit a grove into the edge of the MDF for the chipboard to sit in you get a nice smooth transition that will need very little effort to glass over seamlessly.









Notice the black fiberglass showing through the green body filler (I use black glass). This is due to the surface being so close to perfect that only a thin layer of filler is required.

I would like thoughts and ideas but if you are a DIY or experimenter please don't pass off opinions as fact. I appreciate all input from creditable sources and all questions or ideas from anyone. Thanks.

speakermakers do you build up the FG areas of the chipboard for the boxs where it is a wall of the box area? Only asking cause if the FG is thin then you get cracking and alot of flex from the pressure of sub.

Your work is very nice!!!!!! And from your pics, you have given me new ideas with the chipboard to make a AMP rack in my truck. Thx

by the way... what thickness is the chipboard and where can i get some?

-------------
The best tool in my work shop, is my BRAIN!!!!

When you ask for chip board at an upholstery shop or upholstery supply they will generally give you three options: waterproof board (black 3/16" treated cardboard that is used to make door panels on classic cars), and two thicknesses of true chip board (thick and thin. I keep both thicknesses of chip board in stock at all times but use the thinner of the two the most. I don't use the black water proof board at all. Chip board sells for $1.50 or less a sheet.

All areas that I use chip board on are then covered in aluminum foil, waxed, and then glassed over with "fatmat". I then remove the entire sandwich, peel off the chip board and aluminum, and bond the new fiberglass piece back in. When I am done the structure is strong enough to support a Mack truck. I am quite particular about how strong my glass work is. :)

You will notice the cross pattern on the surface of my glass work. This is because I use a well thought out series of glass grades, layers & application to achieve a high strength to weight ratio as well as dimensional stability. I am a big believer in over building everything, though my techniques allow my final glass areas to be much denser, stronger, and thinner than you will typically see.

Thanks for the complements!

definitely gives me some ideas too. ill have to see if they carry that stuff at the upholstery distributor i get my headliner and vinyl material from. im planning a glass box in my truck for my up-coming RE XXX12 and space is at a premium so ill be using a decent amount of glass.

i have a technique that you might be able to use to fill in some finer detail in your overall shapes with fiberglass using modeling clay as a surface that you can sculpt complex shapes and then glass over without having the clay stick to the glass. you can also take a physical object and press it into the clay to get a mold and then glass into the mold to make a fiberglass replica. this is good for logos and badges that are too small or complicated to make out of wood. you can also fill the mold with some sort of clear resin then paint it and light it up from underneath.

im far from an expert with fiberglass so i havent used this idea much at all but i dont see how it could fail for making small parts.

-------------

I'm interested. Post some pics please.

sorry i havent actually made anything with this technique yet but i will be using it in the next few weeks. im building a fiberglass box for a 12 inch RE XXX and im going to make the "XXX" logo out of pure resin and mold it into a panel and have it back-lit. it will be painted probably black but it will still glow when the lights are off. ive gone through it a thousand times in my head and i honestly dont see how anything can go wrong. ill definitely post pics and a tutorial when im done.

-------------

So you are glassing over the chipboard, using it as a form basically? then removing the chipboard and bonding back in the glass piece?

-------------
Gary Sather

Sorry. and what do you mean glassed over with fatmat. fatmat is a peel and stick sound deaden-er like dynamat, not fiberglass.

-------------
Gary Sather

Also for application where you need more fiberglass than wood for lighter weight etc a technique I've used is making a wood frame using 1x2 and mdf rings for the subs. I will wrap the frame in thick trunk liner thick carped. Non backed. So essentially all it is is a carpeted frame. Then I use resin mixed with bondo for extra strength and glass the carpet. Which gives me one solig glassed box that is extremely strong and light for the size but still fairly heavy considering. Over all thickness of the glass ends up being about 1/3" thick. And extra strong. I ususlly dynamat the inside and it helps it sound acoustically more like a wood box with all the strngth but less weight and is a fast process.

This was one of those boxes that ended wrapped in suede.   I have photos of the process I can also post.

-------------
Gary Sather

the glassed carpet box is strong but a properly layered fiberglass box will be stronger because of the fabric direction. if you alternate the directions through each layer you will end up with something extremely strong. the carpet will have air in it too because theres no way to really push the air out, all you can do is saturate it as best as you can but air will still be there in some spots, its just too thick. nothing against you personally, that box and amp rack does look pretty nice but its probably not as strong as you think. did you cover it with suede?

-------------

Covered it in suede. Plus strength is tried and tested. This box has been going tough as a demo car for 2 years now. 0 issues in strength ir performance.

-------------
Gary Sather

yea im not saying it isnt strong enough for some installs, my point was that actual fiberglass is still stonger. hell i made some pods a while back for some tweeters out of a thin layer of fleece and soaked it in resin and you can probably hit it with a sledge hammer, i was really surprised at how strong it was after just one layer. plus the fact that your box has nothing but curves also has a lot to do with why it holds up nicely, if it wasnt so curved it would probably flex a little.

honestly if it flexes now you wouldnt even know it because its covered in suede, if it was painted, that would be the true test of whether or not it flexes.

-------------

Well I was just throwing this process out there. It IS strong. And it ran painted for a few months before getting wrapped in suede. No flexing. Glassed clean through over 1/3" thick. It worgs great when you need curves and a slightly faster process.

-------------
Gary Sather

how hard is it usually to sand something like that? it mush be pretty rough when its first cured.

-------------

No harder than sanding any other fg application.

-------------
Gary Sather

speakermakers do you remove the hardboard after the FGing or just leave it? I would assume that the FG just bonds to it like wood?

-------------
The best tool in my work shop, is my BRAIN!!!!

I guess there have been a few points of confusion on my original post.

What Fatmat is

How I use chip board

How this technique saves you time sanding

When I refer to Fatmat I am not refering to the sound deadener product. Fatmat is a term used in large production fiberglass industries like boat building and hot tubs. Fatmat is a technique where you pre-layer modified twill with random chop mat using solvent based spray glue. This allows you to apply resin to the fiberglass before putting it on your project. Doing it this way also allows you to roll out any excess resin giving you the perfect resin to fiberglass ratio for an ultra strong and light wight product.



Yes I remove the chip board. I tape and wax the chip board before I lay glass on it. I then bond the glass back onto my project. My projects are much lighter weight and much stronger than you will typically find in the car audio world.



This technique saves you time sanding. Because the glass is preformed and rolled smooth. The final layup requires much much less body filler and consequently sanding. As an added benefit the project has dimensional stability. It won't warp in the sun and there is not much filler on it so it won't shrink and show sand lines through the paint work a couple of months down the road.