How long has the floor been down? It takes some time for the flooring to expand and 'grow' the seam together. Did your installer miscut and you have an open seam? How much is it open?

the floor was installed in early summer. we raised the issue immediately, but were told initially that was just the way it was going to be based on when our contractor contacted the company hired to install the flooring. When our contractor looked at it again after a few weeks had gone by, he too decided that it was done correctly. The company came back in, cleaned up the seam as there was excessive adhesive in various parts of the seam. We were told then that due to the size of our small kitchen we could have had the one seam running down the center lengthwise or two seams running width wise.

The seam itself appears raised in areas, while in other areas, it is not visible at all. I won't necessarily say the seam is open, it just appears raised in some areas. We have been told that the thickness of marmoleum varies which why it is raised in spots. We have also been told that the material swells in the heat. . While we get lots of afternoon sun in the kitchen, we do not get hot weather very often, and then it typically never gets higher than in the mid 80's.

Has Forbo (the manufacturer) looked at the floor and, if so, what did they say?

Think twice about the welding rod solution...you will definitely see that.

Did they try and roll the seam flat with a hand roller? Anything else they attempt to improve the appearance?

I've worked with this product and it is very fussy stuff. It is a challenge to install perfectly, even for a seasoned and trained installer.

But it is a very nice product.

I had the same problem. Easy fix. Don't heat weld. It will look even worse. Scrub the seam with a plastic abrasive sponge, use a little baking soda to get the dirt out. Rinse with cold water until clean. Make a paste with some left over marmoleum scraps. Scrape up tiny pieces (should look like grains of salt) from left over marmoleum with razor blade and kneed paste in the seam with your fingers. The seam will look brand new. Go to the marmoleum web site, the directions are on-line. You can also do this to fill in small dents.

i have marmo in my kitchen and rec room. had it installed by approved vendor that installs this at institutions all over the place around here. their installers have a lot of experience. i opted for the the pattern matching rod in both spots. it has to be "worked " when it's put in, but i'm happy with it. i am a male, so maybe my standards are lower. it's not "invisible" , but not a sore thumb either. the rec room is "rembrandt" i think, and they're very quiet in that pattern. i have fairy blue, i think , in the kitchen, and it is more visible. i am an aesthetic type guy (corian with integral corian sink, flush refrig, etc) but the barely discernable thing doesn't bother me. fwiw, the installer told me he didn't even use the heat weld in his kitchen, but i just don't like open seams

These are just a couple of the issues we're having with the seams on our marmoleum install. These results are after the installer came out to "fix" it. He also went on to tell us we needed to clean/prep the floor, wax it 2x, and seal it. We were told it is necessary and our responsibility. Nothing in the manufacture's info says anything about this. The flooring is perfect and not the issue. Any feedback would be appreciated.

More pics

I would not consider that "fixed", and if he was hired to install a floor that to me would include finishing or sealing said flooring. What does your contract state about the finishing or sealing?