You can wash horse blankets, including T/O’s in a washing machine, but they need to be line dried, and you need a large capacity front loader. Also, you need to wash T/O’s in cold or cool water. Part of the waterproofing is created by the membrane fused to the underside of the top nylon layer, and while this membrane will eventually delamninate, as long as you wash the blanket in cold or cool water, you should get at least 5 years and sometimes more before this happens. This normal delamination is a reaction to UV rays, so short of keeping your horse out of the sun in the winter, there is no way to prevent this eventual delamination. Once delamination starts, you can rewaterproof the T/O’s with a waterproofing spray, but without an intact membrane, the spray on waterproofing will only last 4 – 6 weeks, long enough so the blanket could be used as a back up while the main blanket is being repaired. The washing instructions for most T/O’s list a “mild” detergent and no bleach. The blanket washes are typically substantially more expensive that normal mild detergents, and don’t prolong the life of the blanket any more than following the manufacturer’s washing instructions by using a standard mild detergent. I use powder detergent but only because my extra-large capacity washer has one programmable setting, which I use for blanket washing, and which has 2 washes, multiple rinses, but requires powdered detergent for 2 washes. Other machines with a programmable setting may be able able to use a mild liquid detergent, which also meets the manufacturer’s washing instructions.
There are 2 types of dirt: surface dirt & ground in dirt. “Surface dirt” is pretty much self explanatory, but “ground-in dirt” (my term, not an official one) is dirt that has been ground into the weave of the fabric. Most surface dirt will come out in the washer, but the only way to get ground in dirt out is to hand scrub the outside layer with a stiff brush & detergent, and for this I prefer liquid detergent. You can tell where you are getting dirt loose because the foam from the detergent will start off white, but will turn brown where you have loosened the ground in dirt. The darker the brown, the more dirt you have freed. You can also have stains, and they usually do not come out.
Since I repair blankets, I almost always rewaterproof a blanket after it has been washed or repaired, or give the client detailed instructions so they can same some money by doing it themselves. The best waterproofing I have found is the one with the orange cap sold by Wal-Mart in the tent & camping section, for $6/can. You can also order it on-line, but for reasons no one has been able to explain to me, it cost $7/can online, but only $6/can in a Wal-Mart store. Wal-Mart has a different waterproofing spray in the shoe department, but that one does not work well on horse blankets.
Most revues have been positive for the orange cap waterproofing. You will need 2-1/2 – 3 cans for a 78″ blanket, less for smaller blankets, more for larger blankets. The amount of spray you will need also depends on how much of the original waterproofing is still intact, as the original top layer waterproofing is also affected by UV rays. I hang the blankets over a garment rack, and start from the top and spray a strip across, spraying until the material is saturated & I see fluid running down the material. Then I move down & spray the next strip across. By hanging the blanket, the “run off” will be absorbed by the parts of the blanket below where you started, and will be used, not wasted. I usually respray the top when I have finished the first side, so I have a clear demarcation line & know where to start the 2nd line. The spray will be one color when wet and will either be lighter or darker when dry, so you want to have enough spray on hand to do the entire blanket. Otherwise, when it dries, you may not be able to tell where you left off.
If any repairs have been done, you will need to seal the needle holes with waterproofing.
You need to keep the blanket dry from rain while the waterproofing agent cures & dries, and I personally find the odor of the spray really nasty, so I try to inhale as little as possible, and when possible, I do the waterproofing outdoors. In the summer, when I can hang the T/O’s outdoors in the sun, the waterproofing will cure/dry in as little as 12 hours, and the odor will dissipate in 24. At this time of year, I have to waterproof blankets in the garage, but I open both big car doors, but the people door (which is not on same side as the 2 car doors) so I get cross ventilation. When it is below 50F, the waterproofing takes at least 48 hours to dry/cure & at least another 24 to 36 hours for the odor to dissipate. However, if the smell has not completely dissipated, you can put the T/O back on the horse, especially if he/she lives out 24/7. Very few barns are heated or air tight, so if a little odor is left, you can put the blanket back on the horse in the barn.
A few last comments. If you decide to buy a front loader to wash horse blankets, buy the one with the biggest capacity you can find, or look for a used commercial triple load washer. Some laundromats do allow horse blankets to be washed, but they usually have one machine designated for that purpose, and if you wish to be allowed to continue to wash horse blankets, bring some old towels with you and wipe out the tub to remove any leftover hair.
Top loaders should not be used to wash horse blankets because they spin like a whirl wind, which spins the dirt floating in the water into the folds of the blanket. Front loaders spin on the other axis, so the blanket gets lifted to the top and dropped back into the dirty water, so it also moves more, rather than have the floating dirt spun into the folds. The blankets also move better in a front loader, and the more they can move in the washer, the cleaner they will be.