How should I apply filler in small increments?

E

Evil_Fiz

Promoted Users
I have never applied filler so this is all new to me. I have researched how to properly apply the filler and believe I have a good understanding of the process. The Rage Ultra/Rage Extra 50/50 mix provides a long working time but can get rather pricy. I have seen several positive endorsements of 3M Platinum/Plus here but the 3M website says it has a 3-5 minute working window. That said, is it possible or advisable to mix small batches and apply them over a large area in a section? If so, do I need to sand as I go along or is there a window in which the product will adhere to the previous application? This will all be done over SPI epoxy within the 7-day window. The temps will be in the low to mid 70s in North Florida when the filler is applied.

Thanks,
Emil
 
Don’t apply body filler over unsanded body filler.

It’s much better if you can to mix up a lot for a larger area and use a wider spreader to coat the entire area quickly. If you do it with lots of smaller applications you have all kinds of inconsistent areas of filler thickness that you have to go back and refill and it creates a lot more work.

I’m a fan of USC White Gold, a lot cheaper than Platinum and has a longer working window. I used to use Platinum (which is what I’m using in this video.) This is over 3 yrs old, today I spread the filler much prettier when applying it so I have less sanding. Smooth the edges out so you don’t have a ridge to taper in.

 
When using filler other than Evercoat Ultra & Evercoat Ultra Extra mixed 50/50, you can use other fillers with a working time up to 7-8 minutes by mixing and spreading filler with air and metal temps between 60 and 65 degrees.

This sometimes requires getting up in the early morning hours to get the spread done.

I had to do this with the roof of my car. Up at 3:00am to have working temps to use. I used 3M Platiuum 01171.

Filler spread
20210906_113134.jpg


20210906_113921.jpg


Sanded 80 grit, then 180
20210906_161020.jpg


Two sprayed coats of SPI epoxy over filler.
20210918_201019.jpg

20210918_200917.jpg
 
Last edited:
To answer your other question about applying filler over filler, I always put a scratch in the filler before applying more filler over it. I usually use a 80 grit scratch, sometimes a 180 grit scratch.

When I skimmed coated the roof, I made about a 2' wide by the length of the roof, spread. While that was setting up and drying, I would clean my spreader board. Once that was done I would feather sand the edge of the filler I just spread with 80 grit.

Then I proceed to mix more filler and spread another 2' wide section over lapping the Feather sanded 80 grit edge.

I continued this process until the roof was fully skimmed coated.
 
Last edited:
I've found that adding the hardener by weight vs. eyeballing it (even following the pictures on the can) results in a lot less hardener and longer working time, and it sets up just fine.
Most filler calls for 2% hardener by weight, but check TDS for whatever you use.
A cheap digital kitchen scale that can be set to grams is perfect for this.
 
I've found that if you spread the filler out on the board it will last longer. If kept in a ball, it will create more heat then it'll cure faster and be unusable.
 
Dean Jenkins said:
I've found that adding the hardener by weight vs. eyeballing it (even following the pictures on the can) results in a lot less hardener and longer working time, and it sets up just fine.
Most filler calls for 2% hardener by weight, but check TDS for whatever you use.
A cheap digital kitchen scale that can be set to grams is perfect for this.
Click to expand...

Great idea. I hate eyeballing filler hardener!

But, most kitchen scales are tiny, mine's about 6" square. I usually mix on one of those giant boards with the tear off paper. What do you mix on that's small enough that you can still read the display on the scale?

Or should I balance the giant board on a mixing cup so I can still see the numbers? ;-)
 
Spread hardener on a separate sheet,so weigh the bondo then on a small piece of paper squirt out the hardener.Thats what Ive done in the past.I usually do small batches so 100g of bondo then 2g of catalyst.
 
You must log in or register to reply here.
Back
Top