Joining fillers

[chuck112]

Hello everyone,


Here is my problem, my car was broke in to and they used a prybar on the top of the door so i had dents in the roof. when i was sanding down the roof/ door jam. i found out that the person who owned it before me they had some work done on the roof. It is possialbe that it could have been hail damage so i started to sand and found that the filler goes across most of the roof. so heres the question. how do i join two fillers, and i have heard stories that filler will crack when joined with an old filler?

chuck

[Len]

I've never had a problem joining old and new filler. Just grind the surface where the two will be coming together and push the first coat of filler into the grinding scratches and you should be ok.

[chuck112]

when i sanded down the roof the whole roof has filler... so i just need to do a section. When I sanded down the roof there is alot of filler so it has to be joined but in order to do that, there will not be a metal spot to bond the new filler to it will have to bond to old filler. So with that is my question, how do you bond filler on filler... normaly you have to go to bare metal. so i dont have to do the whole roof.


chuck

[Serge]

Like Len said, simply sand and prep the area properly and you should not have any problem. That is of course if the filler that is already on the car is sound...

Sand the area with 80 grid and feather the new filler on the old (don't cut the old filler in a straight line, simply feather it out). Then it's crucial that you remove the dust properly (blow some air at a good pressure). Then when you put the filler in make sure you press on the spreader to make sure the filler goes in the sanding scratches properly. Then sand and finish as usual.

[Phil V]

I agree with Len and Serge. For finishing off the filler blend you migh use a polyester spot putty. Makes the work quite a bit easier for finish block sanding of the filler.