Bondo for a gap filler?

qmiester,

In large amounts, such as that cup, you are right, it will generate a lot of heat as it cures - for that matter, so will polyester resin. In small amounts, the heat increase is not significant. I depending on what i am doing, I mix up an amount from about the size of a pea and up. The mix is not overly critical - too little, and it never cures, but a short amount of experimentation will quickly give you the acceptable range. The nice thing is that the color intensity of the mixed product gives you an accurate guide to the setting time, which is very useful.

I have mixed up some pretty hot batches, and put them into styrene models with no ill affect. If I had to fill a large cavity, however, I would tend to put it on in layers rather than in one giant dollop. The sell this stuff in quart cans, so you will have plenty to experiment with if you try it :-)

Kurt

I use Instafill (drywall filler) and it works fine but does not come in a tube so it gets on your hands.

Kurt,

The only problems I've found with the epoxy type Bondo body filler is the fact that if you don't get your mixture exactly right, you can and will generate a bunch of heat as it cures And I've always worried that it would melt the plastic as it cured. I once had a friend of mine mix some up in a paper cup to apply to his car - he doubled the amount of hardner to try to make it get hard faster - it did, but it also got hot enough the cup charred and you couldn't hold it.

If you don't mind mixing, there is a scale version of Bondo that is way more suitable for model uses. It is called catalyzed body putty, and it is ground much finer than Bondo - as a result you can use it just like you use the laquer based putties. The difference is that is it way stronger (better for nice crisp edges), and cures, ready to sand, in minutes.

Here is a page I made on the subject:

http://wmunderway.8m.com/cont/putty/putty.htm

Kurt

Let me be another person that admits to using Bondo Glazing and Spot putty. There are other spot putty but the Bondo is one that I know works for filling gaps. A couple of $$ will get you a lot of putty.

Hey thanks guys.

There are a lot of good automotive fillers out there that you can use. My recommendation is to go with one of the "spot and glaze" putties as they seem to have the finest texture when dry and sanded. They come in laquers and acrylics, various colors (red, blue, green and orange come to mind) and have various working and sanding times. Dupont has an Acrylic Spot and Glaze (blue) that has about a minute and half working time and can be sanded in 10 minutes. My personal choice is Dupont Laquer Spot 'n Glaze (red) which has about a 10 minute working time and is sandable in about 45 minutes. The only problem is that it comes in a very large tube and costs about 15 bucks. However, that same tube will last me about 6 to 8 years if I take care of it. The laquer seems to hold better to the plastic also.

One thing you have to remember though, is that you have to apply the putty in thin layers. If you apply one thick layer it can take months to completly dry, shrinking as it does. Which means that you can sand it, paint it and come back a month or so later and it has shrunk and even cracked under your paint jop. So take your time, apply a single thin coat, let it dry and sand it. Then apply your second coat the same way. Keep it up until you have the surface the way you want it and 99.9% of the time you will never have any problems.

You need to go to Wal-Mart and look in the auto section by the paint you will find Bondo Glazing and Spot Putty. I have used this for some time and it works great. A 4.5 oz tube for around $5.00. thats my

If you want something like bondo but without buy a big can of it,you can buy testors red
filler.It is like bondo but comes in a tube.I use it and like the properties it has when it
comes to filling gaps and seems.Digger

I've heard of several people around these parts that use Bondo as filler putty. I was going to pick some up the last time I was at Lowe's, but the smallest can they had was just too big for what I would need.