Speedstrip can be problematic on marmoleum. In the 90s they had huge problems with it being used as directed on their product. So much so Forbo engaged us to write their care guidelines and form a network of approved contractors for the care and maintenance. That's where they for the Prochem links from as we are local to the head office and were Prochem dealers.
Here is a video of a marmoleum floor that was done, unsuccessfully, using it with the no scrub, no rinse method listed on the bottle.
http://www.youtube.com/watch?v=lMYHS9tfMhsMarmoleum is comprised of all natural materials (apart from the polyprop backing on tiles) and therefore presents problems not found on vinyls and rubbers.
StripperWhen using stripper it is important that you test for discoloration. Some colours of Marmoleum can yellow. This is damage to the pigments usually from strippers containing sodium meta silicate and cannot be reversed. Speedstrip can work very well on certain colours but you should always use it like a conventional stripper to avoid problems Ie apply, dwell, agitate, vac, rinse. It is important to check if your stripper should be used with hot or cold water. Speedstrip is solvent boosted so hot water causes the active ingredient to evaporate giving you less bond breaking power. if you can find out the manufacture of the sealer/finish previously applied use the same brand stripper as it has been formulated to break down their finishes so will work quicker. It is normal to have to strip a floor 2 or 3 times to get desired results. Be aware that after you remove the initial coats that the floor has less protection from the pads and stripper so adjust their aggression as required to minimise damage to the floor.
Pad ChoiceModern pad technology such as the HOS Akwastrip, 3M SPP have allowed for chemical free stripping of marmoleum. They also leave the floor smooth unlike hi-pro or black pads. For heavy build up it may still be necessary to use more aggressive pads to break through the topcoats. Colour will bleed during stripping. Don't be overly concerned with this. The floor is homogenous so a light sanding of the surface isn't too much of a problem.
RinsingIt is important after stripping to use an acid rinse on the floor to neutralise residue that has been absorbed into the floor. My prerence is to spray this on the slurry as soon as i have scrubbed off the polish to reduce alkaline attack on the floor. Or to have it in the solution tank and feed it through as I go prior to vaccing off. I then scrub the floor with my rotary using a blue or red pad to help smooth of scratching from the more aggressive pads and close up the floor slightly.
Neutralising will ensure that your finish isn't stripped from the bottom up afterwards by alkaline residue. Full drying prior to finishing is also essential. On restoration jobs my preference is to leave until the next day before applying top coats.
SealerFor finishing it is important to use a floor sealer prior to any polish. It has a larger molecular structur and on a porous floor gives a better base for finishing. Some products are classed as self sealing. However, on a heavy restoration I have found acrylic seal first is still the best way when using traditional finishes. Flooding the first coat on is often necessary. Pour on a whole bottle and mop it up from the floor rather than mopping on. This will allow the floor to absorb the maximum amount of sealer. Once this has dried (can take over an hour) buff with a dry blue floor pad then apply a further tight coat using your preferred applicator. Continue applying coats followed by buffing when dry until you start to see it forming uniformly on the surface.
Top CoatNow apply your chosen floor finish/polish. This will now be able to sit on the surface giving best protection and appearance. Apply each coat at right angles to the last. My preference is to apply 2-3 coats. Buff with a blue pad to meld together and get some heat into the floor to help cure. Finally apply one more thin coat to give best appearance. Always take the sub floor and floor laying into consideration when choosing a top coat. Hardboard outlines, lumps from nails, trowel marks can Detract from your final finish so always go with a lower shine Matt or satin if these exist. A nice flat floor always looks great with a gloss.
When tackling marmoleum I would always question if the floor actually needs to be chemically stripped. The use of neutral detergents and modern pads may be enough to clean up the floor ready for patching in. The only reason I would strip marmoleum is if the top coat is actually discoloured or contaminated with debris etc. applying sealer to patchy areas and buffing until uniform then top coating can often be the answer on a floor that has only been neglected and not mistreated.
Following the restorative works it is imperative that the client uses cold neutral cleaner and buffs the floor periodically to keep the finish strong. I have seen in commercial buildings all the finish being removed in 4 weeks because of mopping with hot hard surface cleaner. Even using urethane fortified acrylic finish. The toughest sacrificial coating available.
Ensure with any stripping job that you qualify possible paint removal from skirtings due to the nature of the products needed for removal and the aggressive scrubbing that may be required at the base boards. Always carry out room protection as normal to around 3 feet high with mask and shield, roll & stroll or equivalent.
With regard to the OPs floor I would try scrubbing back with neutral cleaner and a red pad. If you have a diamond pad like a twister, KGS Flexis, Supershine even better. Then apply a coat of floor sealer, buff with a blue pad then a couple more coats of your finish with a final high speed buff using a red/tan/white/natural fibre pad to finish. A light mist from a trigger spray with your polish at 1:10 with water during the buffing can help build the desired gloss.
