Filler over jotun 87 epoxy

[vdubz]

Does anyone know if its ok to put body filler over jotun 87 epoxy thats still slightly soft(painted yesterday) as ive never put filler over this stuff before so not sure if it will react? if not i will wait until its fully cured, then sand and apply filler.

 

[anjum]

I would wait until it's fully cured. I don't know about the jotun epoxy but I would have expected lechler to have gone hard already.

 

[langy]

I would wait until it's fully cured. I don't know about the jotun epoxy but I would have expected lechler to have gone hard already.

Correct, Lechlar is pretty rock hard after 2-3 hours, I wouldn't fill on soft epoxy plus it should be keyed for filler

 

[vdubz]

I do usually use the lechler, but i didn't have any left, so i just brushed some jotun on instead, i find that the jotun stuff does usually take a couple of days before it goes rock solid as its alot thicker than the lechler. Langy you say that the epoxy should be keyed, i understand if its cured that it should be keyed but i always thought that filler (if compatible) could be put over epoxy without needing to be keyed if the epoxy wasn't 100% cured? that way it would make a chemical bond?

 

[langy]

I do usually use the lechler, but i didn't have any left, so i just brushed some jotun on instead, i find that the jotun stuff does usually take a couple of days before it goes rock solid as its alot thicker than the lechler. Langy you say that the epoxy should be keyed, i understand if its cured that it should be keyed but i always thought that filler (if compatible) could be put over epoxy without needing to be keyed if the epoxy wasn't 100% cured? that way it would make a chemical bond?

I would never rely on the chemical bond once the epoxy has cured.

 

[anjum]

Ditto, for filling a mechanical key is almost essential.

 

[vdubz]

Ok thanks, I never did like the thought of spreading filler over unsanded primer and have never actually done it that way before, i just thought about doing it on this occasion to take advantage of the slow curing jotun epoxy. I guess theres no real way of knowing if the filler has made a proper chemical bond to the epoxy or not without taking a hammer to it to find out! looks like i will stick with the good ole mechanical bond to be on the safe side.

 

[langy]

Ok thanks, I never did like the thought of spreading filler over unsanded primer and have never actually done it that way before, i just thought about doing it on this occasion to take advantage of the slow curing jotun epoxy. I guess theres no real way of knowing if the filler has made a proper chemical bond to the epoxy or not without taking a hammer to it to find out! looks like i will stick with the good ole mechanical bond to be on the safe side.

If its not cured and you put something over the top solvents are gonna be trapped or come out later.

 

[vdubz]

If its not cured and you put something over the top solvents are gonna be trapped or come out later.

Yes that is true, but i'm still wondering why lechler(i know its not lechler) would say in there TDS, after 8 to 10 hours it can be over coated with polyester putty , when it says that the lechler epoxy takes 48 hours at 20C to through dry? So they are basically saying you can put filler over there epoxy before its fully cured.

 

[reedx]

If its not cured and you put something over the top solvents are gonna be trapped or come out later.

I thought the idea with epoxy was that curing was a chemical reaction and not solvent evaporation?

Colin

 

[vdubz]

I thought the idea with epoxy was that curing was a chemical reaction and not solvent evaporation?

Colin

Yes its a chemical reaction, but there are still small amounts of solvent in the paint too make it flow, which langy is talking about.

 

[langy]

Yes that is true, but i'm still wondering why lechler(i know its not lechler) would say in there TDS, after 8 to 10 hours it can be over coated with polyester putty , when it says that the lechler epoxy takes 48 hours at 20C to through dry? So they are basically saying you can put filler over there epoxy before its fully cured.

I think your possibly confusing putty with filler, to me they are 2 different products, i've always known stopper as putty, filler is filler, It does seem confusing though.

 

[langy]

I thought the idea with epoxy was that curing was a chemical reaction and not solvent evaporation?

Colin

When you mix it you add 10% thinner, its got to come out somewhere.

 

[vdubz]

I think your possibly confusing putty with filler, to me they are 2 different products, i've always known stopper as putty, filler is filler, It does seem confusing though.

I see, but i would have thought that 2k stopper would have the same ability to possibly trap solvents like a filler would, as they are pretty much the same. I wonder if lechler are talking about a 1k stopper? this would make more sense, as a 1k stopper would be more porous/breathable and still allow the solvents to come out?

 

[langy]

I see, but i would have thought that 2k stopper would have the same ability to possibly trap solvents like a filler would, as they are pretty much the same. I wonder if lechler are talking about a 1k stopper? this would make more sense, as a 1k stopper would be more porous/breathable and still allow the solvents to come out?

Unfortunately I can only advise on how I do it which is Epoxy then leave overnight (about 14-15hrs) then key with 120/150 then fill, I've never had a problem doing it this way so I have no reason to change, everyone I know does it the same way.